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1. 12C(e,e'pN) measurements of short range correlations in the tensor-to-scalar interaction transition region

Author: I. Korover, J.R. Pybus, A. Schmidt, F. Hauenstein, M. Duer, O. Hen, E. Piasetzky, L.B. Weinstein, D.W. Higinbotham, S. Adhikari, K. Adhikari, M.J. Amaryan, Giovanni Angelini, H. Atac, L. Barion, M. Battaglieri, A. Beck, I. Bedlinskiy, Fatiha Benmokhtar, A. Bianconi, A.S. Biselli, S. Boiarinov, W.J. Briscoe, W.K. Brooks, D. Bulumulla, V.D. Burkert, D.S. Carman, A. Celentano, P. Chatagnon, T. Chetry, L. Clark, B. Clary, P.L. Cole, M. Contalbrigo, V. Crede, R. Cruz-Torres, A. D'Angelo, R. De Vita, M. Defurne, A. Denniston, A. Deur, S. Diehl, C. Djalali, R. Dupre, H. Egiyan, M. Ehrhart, A. El Alaoui, L. El Fassi, L. Elouadrhiri, P. Eugenio, R. Fersch, A. Filippi, T. Forest, G. Gavalian, F.X. Girod, E. Golovatch, R.W. Gothe, K.A. Griffioen, M. Guidal, K. Hafidi, H. Hakobyan, N. Harrison, M. Hattawy, T.B. Hayward, D. Heddle, K. Hicks, M. Holtrop, Y. Ilieva, D.G. Ireland, E.L. Isupov, D. Jenkins, H.S. Jo, K. Joo, S. Joosten, D. Keller, M. Khachatryan, A. Khanal, M. Khandaker, A. Kim, C.W. Kim, F.J. Klein, V. Kubarovsky, L. Lanza, M. Leali, P. Lenisa, K. Livingston, V. Lucherini, I.J.D. MacGregor, D. Marchand, N. Markov, L. Marsicano, V. Mascagna, B. McKinnon, S. Mey-Tal Beck, T. Mineeva, M. Mirazita, A. Movsisyan, C. Munoz Camacho, B. Mustapha, P. Nadel-Turonski, K. Neupane, G. Niculescu, M. Osipenko, A.I. Ostrovidov, M. Paolone, L.L. Pappalardo, R. Paremuzyan, E. Pasyuk, W. Phelps, O. Pogorelko, J.W. Price, Y. Prok, D. Protopopescu, B.A. Raue, M. Ripani, J. Ritman, A. Rizzo, G. Rosner, J. Rowley, F. Sabatié, C. Salgado, R.A. Schumacher, E.P. Segarra, Y.G. Sharabian, U. Shrestha, D. Sokhan, O. Soto, N. Sparveris, S. Stepanyan, I.I. Strakovsky, S. Strauch, J.A. Tan, N. Tyler, M. Ungaro, L. Venturelli, H. Voskanyan, E. Voutier, T. Wang, D. Watts, X. Wei, M.H. Wood, N. Zachariou, J. Zhang, Z.W. Zhao, and X. Zheng
Subjects: Physics, QC1-999
Abstract: High-momentum configurations of nucleon pairs at short-distance are probed using measurements of the 12C(e,e′p) and 12C(e,e′pN) reactions (where N is either n or p), at high-Q2 and xB>1.1. The data span a missing-momentum range of 300–1000 MeV/c and are predominantly sensitive to the transition region of the strong nuclear interaction from a Tensor to Scalar interaction. The data are well reproduced by theoretical calculations using the Generalized Contact Formalism with both chiral and phenomenological nucleon-nucleon (NN) interaction models. This agreement suggests that the measured high missing-momentum protons up to 1000 MeV/c predominantly belong to short-ranged correlated (SRC) pairs. The measured 12C(e,e′pN) / 12C(e,e′p) and 12C(e,e′pp) / 12C(e,e′pn) cross-section ratios are consistent with a decrease in the fraction of proton-neutron SRC pairs and increase in the fraction of proton-proton SRC pairs with increasing missing momentum. This confirms the transition from an isospin-dependent tensor NN interaction at ∼400 MeV/c to an isospin-independent scalar interaction at high-momentum around ∼800 MeV/c as predicted by theoretical calculation.
Published: 2021
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2. Measurement of the beam spin asymmetry of e→p→e′p′η in the deep-inelastic regime with CLAS

Author: B. Zhao, A. Kim, K. Joo, I. Bedlinskiy, W. Kim, V. Kubarovsky, M. Ungaro, S. Adhikari, Z. Akbar, G. Angelini, H. Avakian, J. Ball, N.A. Baltzell, L. Barion, M. Bashkanov, M. Battaglieri, V. Batourine, A.S. Biselli, S. Boiarinov, W.J. Briscoe, W.K. Brooks, V.D. Burkert, D.S. Carman, A. Celentano, P. Chatagnon, T. Chetry, G. Ciullo, L. Clark, B.A. Clary, P.L. Cole, M. Contalbrigo, V. Crede, A. D'Angelo, N. Dashyan, R. De Vita, E. De Sanctis, M. Defurne, A. Deur, S. Diehl, C. Djalali, R. Dupre, H. Egiyan, M. Ehrhart, A. El Alaoui, L. El Fassi, P. Eugenio, A. Filippi, T.A. Forest, G. Gavalian, Y. Ghandilyan, G.P. Gilfoyle, F.X. Girod, E. Golovatch, R.W. Gothe, K.A. Griffioen, M. Guidal, L. Guo, K. Hafidi, H. Hakobyan, N. Harrison, M. Hattawy, D. Heddle, K. Hicks, M. Holtrop, Y. Ilieva, D.G. Ireland, B.S. Ishkhanov, E.L. Isupov, D. Jenkins, H.S. Jo, S. Johnston, M.L. Kabir, D. Keller, G. Khachatryan, M. Khachatryan, M. Khandaker, A. Klein, F.J. Klein, S.E. Kuhn, S.V. Kuleshov, L. Lanza, P. Lenisa, K. Livingston, I.J.D. MacGregor, D. Marchand, N. Markov, B. McKinnon, C.A. Meyer, Z.E. Meziani, M. Mirazita, V. Mokeev, R.A. Montgomery, C. Munoz Camacho, P. Nadel-Turonski, S. Niccolai, G. Niculescu, M. Osipenko, A.I. Ostrovidov, M. Paolone, R. Paremuzyan, K. Park, O. Pogorelko, J.W. Price, Y. Prok, D. Protopopescu, M. Ripani, A. Rizzo, G. Rosner, P. Rossi, F. Sabatié, C. Salgado, R.A. Schumacher, Y.G. Sharabian, Iu. Skorodumina, G.D. Smith, D. Sokhan, N. Sparveris, S. Stepanyan, I.I. Strakovsky, S. Strauch, M. Taiuti, J.A. Tan, H. Voskanyan, E. Voutier, R. Wang, X. Wei, M.H. Wood, N. Zachariou, J. Zhang, and Z.W. Zhao
Subjects: Physics, QC1-999
Abstract: The beam spin asymmetry of the exclusive pseudoscalar channel e→p→e′p′η was measured for the first time in the deep-inelastic regime (W>2 GeV/c2 and Q2>1 GeV2/c2) using a longitudinally polarized 5.78 GeV electron beam at Jefferson Lab with the CEBAF Large Acceptance Spectrometer. The data were accumulated in 144 four-dimensional bins of Q2, xB, −t and ϕ over a wide kinematic range, where ϕ is the azimuthal angle between the lepton and hadron scattering planes, The measured azimuthal dependence with large amplitudes of the sin⁡ϕ moments is a clear indication of a substantial contribution to the polarized cross-section from transversely polarized virtual photons. In the framework of generalized parton distributions (GPDs) this contribution is expressed via longitudinal-transverse interference between chiral-even and chiral-odd GPDs. The experimental results are compared to the existing theoretical models demonstrating the sensitivity to the product of chiral-odd and chiral-even GPDs and provide new constraints to the existing GPD parameterizations. Keywords: Nucleon structure, CLAS collaboration, Deeply Virtual Meson Production, Chiral-odd generalized parton distributions
Published: 2019
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3. First results on nucleon resonance photocouplings from the γp → π+π−p reaction

Author: E. Golovatch, V.D. Burkert, D.S. Carman, R.W. Gothe, K. Hicks, B.S. Ishkhanov, V.I. Mokeev, E. Pasyuk, S. Adhikari, Z. Akbar, M.J. Amaryan, H. Avakian, J. Ball, L. Barion, M. Bashkanov, M. Battaglieri, I. Bedlinskiy, A.S. Biselli, S. Boiarinov, W.J. Briscoe, F. Cao, A. Celentano, P. Chatagnon, T. Chetry, G. Ciullo, L. Clark, B.A. Clary, P.L. Cole, M. Contalbrigo, V. Crede, A. D'Angelo, N. Dashyan, R. De Vita, E. De Sanctis, M. Defurne, A. Deur, S. Diehl, C. Djalali, M. Dugger, R. Dupre, H. Egiyan, M. Ehrhart, A. El Alaoui, L. El Fassi, L. Elouadrhiri, P. Eugenio, G. Fedotov, R. Fersch, A. Filippi, Y. Ghandilyan, G.P. Gilfoyle, K.L. Giovanetti, F.X. Girod, D.I. Glazier, K.A. Griffioen, M. Guidal, L. Guo, K. Hafidi, H. Hakobyan, N. Harrison, M. Hattawy, D. Heddle, M. Holtrop, Y. Ilieva, D.G. Ireland, E.L. Isupov, D. Jenkins, H.S. Jo, S. Johnston, K. Joo, M.L. Kabir, D. Keller, G. Khachatryan, M. Khachatryan, M. Khandaker, W. Kim, A. Klein, F.J. Klein, V. Kubarovsky, L. Lanza, P. Lenisa, K. Livingston, I.J.D. MacGregor, D. Marchand, N. Markov, B. McKinnon, C.A. Meyer, R.A. Montgomery, A. Movsisyan, C. Munoz Camacho, P. Nadel-Turonski, S. Niccolai, G. Niculescu, M. Osipenko, A.I. Ostrovidov, M. Paolone, R. Paremuzyan, K. Park, O. Pogorelko, J.W. Price, Y. Prok, D. Protopopescu, M. Ripani, D. Riser, A. Rizzo, G. Rosner, F. Sabatié, C. Salgado, R.A. Schumacher, Y.G. Sharabian, Iu. Skorodumina, G.D. Smith, D.I. Sober, D. Sokhan, N. Sparveris, I.I. Strakovsky, S. Strauch, M. Taiuti, J.A. Tan, N. Tyler, M. Ungaro, H. Voskanyan, E. Voutier, R. Wang, X. Wei, M.H. Wood, N. Zachariou, J. Zhang, and Z.W. Zhao
Subjects: Physics, QC1-999
Abstract: We report the first experimental measurements of the nine 1-fold differential cross sections for the γp→π+π−p reaction, obtained with the CLAS detector at Jefferson Laboratory. The measurements cover the invariant mass range of the final state hadrons from 1.6 GeV
Published: 2019
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4. Beam–target helicity asymmetry E in K+Σ− photoproduction on the neutron

Author: N. Zachariou, D.P. Watts, J. Fleming, A.V. Sarantsev, V.A. Nikonov, A. D'Angelo, M. Bashkanov, C. Hanretty, T. Kageya, F.J. Klein, M. Lowry, H. Lu, A. Sandorfi, X. Wei, I. Zonta, K.P. Adhikari, S. Adhikari, M.J. Amaryan, G. Angelini, G. Asryan, H. Atac, L. Barion, C. Bass, M. Battaglieri, I. Bedlinskiy, F. Benmokhtar, A. Bianconi, A.S. Biselli, F. Bossù, S. Boiarinov, W.J. Briscoe, W.K. Brooks, D. Bulumulla, V. Burkert, D.S. Carman, J.C. Carvajal, A. Celentano, G. Charles, P. Chatagnon, T. Chetry, G. Ciullo, P.L. Cole, M. Contalbrigo, N. Dashyan, R. De Vita, A. Deur, S. Diehl, C. Djalali, R. Dupre, H. Egiyan, M. Ehrhart, A. El Alaoui, P. Eugenio, S. Fegan, R. Fersch, A. Filippi, G. Gavalian, N. Gevorgyan, Y. Ghandilyan, G.P. Gilfoyle, F.X. Girod, W. Gohn, E. Golovatch, R.W. Gothe, K.A. Griffioen, M. Guidal, K. Hafidi, H. Hakobyan, M. Hattawy, D. Heddle, K. Hicks, D. Ho, M. Holtrop, Y. Ilieva, D.G. Ireland, B.S. Ishkhanov, E.L. Isupov, D. Jenkins, H.S. Jo, K. Joo, S.J. Joosten, D. Keller, M. Khachatryan, A. Khanal, M. Khandaker, C.W. Kim, W. Kim, V. Kubarovsky, L. Lanza, M. Leali, P. Lenisa, K. Livingston, I.J.D. MacGregor, D. Marchand, N. Markov, L. Marsicano, V. Mascagna, M. Mayer, B. McKinnon, Z.E. Meziani, T. Mineeva, V. Mokeev, E. Munevar, C. Munoz Camacho, P. Nadel Turonski, T.R. O'Connell, M. Osipenko, A.I. Ostrovidov, M. Paolone, L.L. Pappalardo, K. Park, E. Pasyuk, P. Peng, W. Phelps, O. Pogorelko, J. Poudel, J.W. Price, Y. Prok, A.J.R. Puckett, B.A. Raue, M. Ripani, A. Rizzo, G. Rosner, C. Salgado, A. Schmidt, R.A. Schumacher, U. Shrestha, D. Sokhan, O. Soto, N. Sparveris, I.I. Strakovsky, S. Strauch, J.A. Tan, N. Tyler, M. Ungaro, L. Venturelli, H. Voskanyan, E. Voutier, N.K. Walford, C.S. Whisnant, M.H. Wood, J. Zhang, and Z.W. Zhao
Subjects: Physics, QC1-999
Abstract: We report a measurement of a beam–target double-polarisation observable (E) for the γ→n→(p)→K+Σ−(p) reaction. The data were obtained impinging the circularly-polarised energy-tagged photon beam of Hall B at Jefferson Lab on a longitudinally-polarised frozen-spin hydrogen deuteride (HD) nuclear target. The E observable for an effective neutron target was determined for centre-of-mass energies 1.70≤W≤2.30 GeV, with reaction products detected over a wide angular acceptance by the CLAS spectrometer. These new double-polarisation data give unique constraints on the strange decays of excited neutron states. Inclusion of the new data within the Bonn-Gatchina theoretical model results in significant changes for the extracted photocouplings of a number of established nucleon resonances. Possible improvements in the PWA description of the experimental data with additional “missing” resonance states, including the N(2120)3/2− resonance, are also quantified.
Published: 2020
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5. Evidence for the N′(1720)3/2+ nucleon resonance from combined studies of CLAS π+π−p photo- and electroproduction data

Author: V.I. Mokeev, V.D. Burkert, D.S. Carman, L. Elouadrhiri, E. Golovatch, R.W. Gothe, K. Hicks, B.S. Ishkhanov, E.L. Isupov, K. Joo, N. Markov, E. Pasyuk, and A. Trivedi
Subjects: Two pion production, Resonance couplings, Missing resonances, Physics, QC1-999
Abstract: The analysis of the nine 1-fold differential cross sections for the γr,vp→π+π−p photo- and electroproduction reactions obtained with the CLAS detector at Jefferson Laboratory was carried out with the goal to establish the contributing resonances in the mass range from 1.6 GeV to 1.8 GeV. In order to describe the photo- and electroproduction data with Q2-independent resonance masses and hadronic decay widths in the Q2 range below 1.5 GeV2, it was found that an N′(1720)3/2+ state is required in addition to the already well-established nucleon resonances. This work demonstrates that the combined studies of π+π−p photo- and electroproduction data are vital for the observation of this resonance. The contributions from the N′(1720)3/2+ state and the already established N(1720)3/2+ state with a mass of 1.745 GeV are well separated by their different hadronic decays to the πΔ and ρp final states and the different Q2-evolution of their photo-/electroexcitation amplitudes. The N′(1720)3/2+ state is the first recently established baryon resonance for which the results on the Q2-evolution of the photo-/electrocouplings have become available. These results are important for the exploration of the nature of the “missing” baryon resonances.
Published: 2020
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6. Semi-inclusive π0 target and beam-target asymmetries from 6 GeV electron scattering with CLAS

Author: S. Jawalkar, S. Koirala, H. Avakian, P. Bosted, K.A. Griffioen, C. Keith, S.E. Kuhn, K.P. Adhikari, S. Adhikari, D. Adikaram, Z. Akbar, M.J. Amaryan, S. Anefalos Pereira, J. Ball, N.A. Baltzell, M. Battaglieri, V. Batourine, I. Bedlinskiy, A.S. Biselli, S. Boiarinov, W.J. Briscoe, J. Brock, W.K. Brooks, S. Bültmann, V.D. Burkert, Frank Thanh Cao, C. Carlin, D.S. Carman, A. Celentano, G. Charles, T. Chetry, G. Ciullo, L. Clark, L. Colaneri, P.L. Cole, M. Contalbrigo, O. Cortes, V. Crede, A. D'Angelo, N. Dashyan, R. De Vita, E. De Sanctis, M. Defurne, A. Deur, C. Djalali, G. Ddoge, R. Dupre, H. Egiyan, A. El Alaoui, L. El Fassi, L. Elouadrhiri, P. Eugenio, G. Fedotov, S. Fegan, R. Fersch, A. Filippi, J.A. Fleming, T.A. Forest, A. Fradi, M. Garçon, Y. Ghandilyan, G.P. Gilfoyle, K.L. Giovanetti, F.X. Girod, C. Gleason, W. Gohn, E. Golovatch, R.W. Gothe, M. Guidal, N. Guler, L. Guo, H. Hakobyan, C. Hanretty, N. Harrison, M. Hattawy, D. Heddle, K. Hicks, G. Hollis, M. Holtrop, S.M. Hughes, Y. Ilieva, D.G. Ireland, B.S. Ishkhanov, E.L. Isupov, D. Jenkins, H. Jiang, K. Joo, S. Joosten, D. Keller, G. Khachatryan, M. Khachatryan, M. Khandaker, A. Kim, W. Kim, A. Klein, F.J. Klein, V. Kubarovsky, S.V. Kuleshov, L. Lanza, P. Lenisa, K. Livingston, H.Y. Lu, I.J.D. MacGregor, N. Markov, M. Mayer, M.E. McCracken, B. McKinnon, C.A. Meyer, T. Mineeva, M. Mirazita, V. Mokeev, R.A. Montgomery, A. Movsisyan, C. Munoz Camacho, P. Nadel-Turonski, L.A. Net, S. Niccolai, G. Niculescu, I. Niculescu, M. Osipenko, A.I. Ostrovidov, R. Paremuzyan, K. Park, E. Pasyuk, E. Phelps, W. Phelps, J. Pierce, S. Pisano, O. Pogorelko, J.W. Price, Y. Prok, D. Protopopescu, B.A. Raue, M. Ripani, D. Riser, A. Rizzo, G. Rosner, P. Rossi, F. Sabatié, C. Salgado, R.A. Schumacher, E. Seder, Y.G. Sharabian, A. Simonyan, Iu. Skorodumina, G.D. Smith, D.I. Sober, D. Sokhan, N. Sparveris, I. Stankovic, S. Strauch, M. Taiuti, M. Ungaro, H. Voskanyan, E. Voutier, N.K. Walford, D.P. Watts, X. Wei, L.B. Weinstein, M.H. Wood, N. Zachariou, J. Zhang, and Z.W. Zhao
Subjects: Physics, QC1-999
Abstract: We present precision measurements of the target and beam-target spin asymmetries from neutral pion electroproduction in deep-inelastic scattering (DIS) using the CEBAF Large Acceptance Spectrometer (CLAS) at Jefferson Lab. We scattered 6-GeV, longitudinally polarized electrons off longitudinally polarized protons in a cryogenic 14NH3 target, and extracted double and single target spin asymmetries for ep→e′π0X in multidimensional bins in four-momentum transfer (1.0
Published: 2018
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7. Differential cross section for γd → ωd using CLAS at Jefferson Lab

Author: T. Chetry, K. Hicks, N. Compton, M. Sargsian, S. Adhikari, J. Ball, I. Balossino, L. Barion, M. Battaglieri, V. Batourine, I. Bedlinskiy, A.S. Biselli, S. Boiarinov, W.J. Briscoe, W.K. Brooks, V.D. Burkert, D.S. Carman, A. Celentano, G. Charles, G. Ciullo, L. Clark, Brandon A. Clary, P.L. Cole, M. Contalbrigo, V. Crede, A. D'Angelo, N. Dashyan, R. De Vita, E. De Sanctis, A. Deur, C. Djalali, R. Dupre, A. El Alaoui, L. El Fassi, P. Eugenio, G. Fedotov, R. Fersch, A. Filippi, G. Gavalian, Y. Ghandilyan, K.L. Giovanetti, F.X. Girod, E. Golovatch, R.W. Gothe, K.A. Griffioen, L. Guo, K. Hafidi, N. Harrison, M. Hattawy, M. Holtrop, Y. Ilieva, D.G. Ireland, B.S. Ishkhanov, E.L. Isupov, D. Jenkins, S. Johnston, M.L. Kabir, D. Keller, G. Khachatryan, M. Khachatryan, M. Khandaker, A. Kim, W. Kim, F.J. Klein, V. Kubarovsky, L. Lanza, P. Lenisa, K. Livingston, I.J.D. MacGregor, N. Markov, B. McKinnon, V. Mokeev, A. Movsisyan, C. Munoz Camacho, P. Nadel-Turonski, S. Niccolai, G. Niculescu, M. Osipenko, A.I. Ostrovidov, M. Paolone, R. Paremuzyan, K. Park, E. Pasyuk, W. Phelps, O. Pogorelko, J.W. Price, Y. Prok, M. Ripani, D. Riser, B.G. Ritchie, A. Rizzo, G. Rosner, C. Salgado, R.A. Schumacher, Iu. Skorodumina, G.D. Smith, D.I. Sober, D. Sokhan, N. Sparveris, S. Stepanyan, I.I. Strakovsky, S. Strauch, M. Taiuti, J.A. Tan, M. Ungaro, H. Voskanyan, E. Voutier, L.B. Weinstein, M.H. Wood, N. Zachariou, J. Zhang, and Z.W. Zhao
Subjects: Physics, QC1-999
Abstract: The cross section for coherent ω-meson photoproduction off the deuteron has been measured for the first time as a function of the momentum transfer t=(Pγ−Pω)2 and photon energy Eγ using the CLAS detector at the Thomas Jefferson National Accelerator Facility. The cross sections are measured in the energy range 1.4
Published: 2018
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8. Measurement of nuclear transparency ratios for protons and neutrons

Author: M. Duer, O. Hen, E. Piasetzky, L.B. Weinstein, A. Schmidt, I. Korover, E.O. Cohen, H. Hakobyan, S. Adhikari, G. Angelini, H. Avakian, C. Ayerbe Gayoso, L. Barion, M. Battaglieri, A. Beck, I. Bedlinskiy, A.S. Biselli, S. Boiarinov, W.J. Briscoe, W. Brooks, V.D. Burkert, F. Cao, D.S. Carman, A. Celentano, P. Chatagnon, T. Chetry, G. Ciullo, P.L. Cole, M. Contalbrigo, O. Cortes, V. Crede, R. Cruz Torres, A. D'Angelo, N. Dashyan, R. De Vita, E. De Sanctis, A. Deur, S. Diehl, C. Djalali, R. Dupre, Burcu Duran, H. Egiyan, M. Ehrhart, A. El Alaoui, L. El Fassi, P. Eugenio, A. Filippi, T.A. Forest, G.P. Gilfoyle, F.X. Girod, E. Golovatch, R.W. Gothe, K.A. Griffioen, M. Guidal, L. Guo, K. Hafidi, C. Hanretty, N. Harrison, M. Hattawy, F. Hauenstein, T.B. Hayward, D. Heddle, M. Holtrop, Y. Ilieva, D.G. Ireland, B.S. Ishkhanov, E.L. Isupov, H.S. Jo, S. Johnston, K. Joo, S. Joosten, D. Keller, G. Khachatryan, M. Khachatryan, A. Khanal, M. Khandaker, A. Kim, W. Kim, A. Klein, F.J. Klein, V. Kubarovsky, S.E. Kuhn, S.V. Kuleshov, L. Lanza, G. Laskaris, P. Lenisa, K. Livingston, I.J.D. MacGregor, D. Marchand, B. McKinnon, S. Mey-Tal Beck, T. Mineeva, M. Mirazita, V. Mokeev, R.A. Montgomery, A. Movsisyan, C. Munoz Camacho, B. Mustapha, P. Nadel-Turonski, S. Niccolai, G. Niculescu, M. Osipenko, A.I. Ostrovidov, M. Paolone, L.L. Pappalardo, R. Paremuzyan, E. Pasyuk, M. Patsyuk, D. Payette, J. Price, D. Pocanic, O. Pogorelko, Y. Prok, D. Protopopescu, B.A. Raue, M. Ripani, D. Riser, A. Rizzo, G. Rosner, P. Rossi, F. Sabatié, C. Salgado, B.A. Schmookler, R.A. Schumacher, E.P. Segarra, Y.G. Sharabian, Iu. Skorodumina, D. Sokhan, O. Soto, N. Sparveris, S. Stepanyan, S. Strauch, M. Taiuti, J.A. Tan, M. Ungaro, H. Voskanyan, E. Voutier, R. Wang, X. Wei, N. Zachariou, J. Zhang, Z.W. Zhao, and X. Zheng
Subjects: Physics, QC1-999
Abstract: This paper presents, for the first time, measurements of neutron transparency ratios for nuclei relative to C measured using the (e,e′n) reaction, spanning measured neutron momenta of 1.4 to 2.4 GeV/c. The transparency ratios were extracted in two kinematical regions, corresponding to knockout of mean-field nucleons and to the breakup of Short-Range Correlated nucleon pairs. The extracted neutron transparency ratios are consistent with each other for the two measured kinematical regions and agree with the proton transparencies extracted from new and previous (e,e′p) measurements, including those from neutron-rich nuclei such as lead. The data also agree with and confirm the Glauber approximation that is commonly used to interpret experimental data. The nuclear-mass-dependence of the extracted transparencies scales as Aα with α=−0.289±0.007, which is consistent with nuclear-surface dominance of the reactions.
Published: 2019
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9. Hard exclusive pion electroproduction at backward angles with CLAS

Author: K. Park, M. Guidal, R.W. Gothe, B. Pire, K. Semenov-Tian-Shansky, J.-M. Laget, K.P. Adhikari, S. Adhikari, Z. Akbar, H. Avakian, J. Ball, I. Balossino, N.A. Baltzell, L. Barion, M. Battaglieri, I. Bedlinskiy, A.S. Biselli, W.J. Briscoe, W.K. Brooks, V.D. Burkert, F.T. Cao, D.S. Carman, A. Celentano, G. Charles, T. Chetry, G. Ciullo, L. Clark, P.L. Cole, M. Contalbrigo, V. Crede, A. D'Angelo, N. Dashyan, R. De Vita, E. De Sanctis, M. Defurne, A. Deur, C. Djalali, R. Dupre, H. Egiyan, A. El Alaoui, L. El Fassi, L. Elouadrhiri, P. Eugenio, G. Fedotov, R. Fersch, A. Filippi, M. Garçon, Y. Ghandilyan, G.P. Gilfoyle, F.X. Girod, E. Golovatch, K.A. Griffioen, L. Guo, K. Hafidi, H. Hakobyan, C. Hanretty, N. Harrison, M. Hattawy, D. Heddle, K. Hicks, M. Holtrop, C.E. Hyde, Y. Ilieva, D.G. Ireland, B.S. Ishkhanov, E.L. Isupov, D. Jenkins, S. Johnston, K. Joo, M.L. Kabir, D. Keller, G. Khachatryan, M. Khachatryan, M. Khandaker, W. Kim, F.J. Klein, V. Kubarovsky, S.E. Kuhn, L. Lanza, K. Livingston, I.J.D. MacGregor, N. Markov, B. McKinnon, M. Mirazita, V. Mokeev, R.A. Montgomery, C. Munoz Camacho, P. Nadel-Turonski, S. Niccolai, G. Niculescu, M. Osipenko, M. Paolone, R. Paremuzyan, E. Pasyuk, W. Phelps, O. Pogorelko, J. Poudel, J.W. Price, Y. Prok, D. Protopopescu, M. Ripani, A. Rizzo, P. Rossi, F. Sabatié, C. Salgado, R.A. Schumacher, Y. Sharabian, Iu. Skorodumina, G.D. Smith, D. Sokhan, N. Sparveris, S. Stepanyan, I.I. Strakovsky, S. Strauch, M. Taiuti, J.A. Tan, M. Ungaro, H. Voskanyan, E. Voutier, X. Wei, N. Zachariou, and J. Zhang
Subjects: Physics, QC1-999
Abstract: We report on the first measurement of cross sections for exclusive deeply virtual pion electroproduction off the proton, ep→e′nπ+, above the resonance region at backward pion center-of-mass angles. The φπ⁎-dependent cross sections were measured, from which we extracted three combinations of structure functions of the proton. Our results are compatible with calculations based on nucleon-to-pion transition distribution amplitudes (TDAs). These non-perturbative objects are defined as matrix elements of three-quark-light-cone-operators and characterize partonic correlations with a particular emphasis on baryon charge distribution inside a nucleon. Keywords: TDA, Exclusive single pion, Eletroproduction, CLAS
Published: 2018
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10. Photon beam asymmetry Σ in the reaction γ→p→pω for Eγ=1.152 to 1.876 GeV

Author: P. Collins, B.G. Ritchie, M. Dugger, F.J. Klein, A.V. Anisovich, E. Klempt, V.A. Nikonov, A. Sarantsev, K.P. Adhikari, S. Adhikari, D. Adikaram, Z. Akbar, S. Anefalos Pereira, H. Avakian, J. Ball, N.A. Baltzell, M. Bashkanov, M. Battaglieri, V. Batourine, I. Bedlinskiy, A.S. Biselli, S. Boiarinov, W.J. Briscoe, W.K. Brooks, V.D. Burkert, Frank Thanh Cao, T. Cao, D.S. Carman, A. Celentano, G. Charles, T. Chetry, G. Ciullo, L. Clark, P.L. Cole, M. Contalbrigo, O. Cortes, V. Crede, N. Dashyan, R. De Vita, E. De Sanctis, M. Defurne, A. Deur, C. Djalali, R. Dupre, H. Egiyan, A. El Alaoui, L. El Fassi, P. Eugenio, G. Fedotov, A. Filippi, J.A. Fleming, Y. Ghandilyan, G.P. Gilfoyle, K.L. Giovanetti, F.X. Girod, D.I. Glazier, C. Gleason, E. Golovatch, R.W. Gothe, K.A. Griffioen, M. Guidal, K. Hafidi, H. Hakobyan, C. Hanretty, N. Harrison, M. Hattawy, D. Heddle, K. Hicks, G. Hollis, M. Holtrop, S.M. Hughes, Y. Ilieva, D.G. Ireland, B.S. Ishkhanov, E.L. Isupov, D. Jenkins, H. Jiang, H.S. Jo, S. Joosten, D. Keller, G. Khachatryan, M. Khachatryan, M. Khandaker, A. Kim, W. Kim, A. Klein, V. Kubarovsky, S.V. Kuleshov, L. Lanza, P. Lenisa, K. Livingston, I.J.D. MacGregor, N. Markov, B. McKinnon, C.A. Meyer, Z.E. Meziani, T. Mineeva, V. Mokeev, R.A. Montgomery, A. Movsisyan, E. Munevar, C. Munoz Camacho, P. Nadel-Turonski, L.A. Net, S. Niccolai, G. Niculescu, I. Niculescu, M. Osipenko, A.I. Ostrovidov, M. Paolone, R. Paremuzyan, K. Park, E. Pasyuk, W. Phelps, S. Pisano, O. Pogorelko, J.W. Price, S. Procureur, Y. Prok, D. Protopopescu, B.A. Raue, M. Ripani, A. Rizzo, G. Rosner, F. Sabatié, C. Salgado, R.A. Schumacher, Y.G. Sharabian, A. Simonyan, Iu. Skorodumina, G.D. Smith, D.I. Sober, D. Sokhan, N. Sparveris, I. Stankovic, S. Stepanyan, I.I. Strakovsky, S. Strauch, M. Taiuti, M. Ungaro, H. Voskanyan, E. Voutier, N.K. Walford, D.P. Watts, X. Wei, M.H. Wood, N. Zachariou, J. Zhang, and Z.W. Zhao
Subjects: Physics, QC1-999
Abstract: Photon beam asymmetry Σ measurements for ω photoproduction in the reaction γ→p→ωp are reported for photon energies from 1.152 to 1.876 GeV. Data were taken using a linearly-polarized tagged photon beam, a cryogenic hydrogen target, and the CLAS spectrometer in Hall B at Jefferson Lab. The measurements obtained markedly increase the size of the database for this observable, extend coverage to higher energies, and resolve discrepancies in previously published data. Comparisons of these new results with predictions from a chiral-quark-based model and from a dynamical coupled-channels model indicate the importance of interferences between t-channel meson exchange and s- and u-channel contributions, underscoring sensitivity to the nucleon resonances included in those descriptions. Comparisons with the Bonn–Gatchina partial-wave analysis indicate the Σ data reported here help to fix the magnitudes of the interference terms between the leading amplitudes in that calculation (Pomeron exchange and the resonant portion of the JP=3/2+ partial wave), as well as the resonant portions of the smaller partial waves with JP=1/2−, 3/2−, and 5/2+. Keywords: Omega photoproduction, Polarization observable, Beam asymmetry
Published: 2017
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11. Photon beam asymmetry Σ for η and η′ photoproduction from the proton

Author: P. Collins, B.G. Ritchie, M. Dugger, A.V. Anisovich, M. Döring, E. Klempt, V.A. Nikonov, D. Rönchen, D. Sadasivan, A. Sarantsev, K.P. Adhikari, Z. Akbar, M.J. Amaryan, S. Anefalos Pereira, H. Avakian, J. Ball, I. Balossino, M. Bashkanov, M. Battaglieri, I. Bedlinskiy, A.S. Biselli, W.J. Briscoe, W.K. Brooks, V.D. Burkert, Frank Thanh Cao, D.S. Carman, A. Celentano, S. Chandavar, G. Charles, T. Chetry, G. Ciullo, L. Clark, L. Colaneri, P.L. Cole, N. Compton, M. Contalbrigo, O. Cortes, V. Crede, A. D'Angelo, N. Dashyan, R. De Vita, E. De Sanctis, A. Deur, C. Djalali, R. Dupre, H. Egiyan, A. El Alaoui, L. El Fassi, L. Elouadrhiri, P. Eugenio, E. Fanchini, G. Fedotov, A. Filippi, J.A. Fleming, Y. Ghandilyan, G.P. Gilfoyle, K.L. Giovanetti, F.X. Girod, D.I. Glazier, C. Gleason, E. Golovatch, R.W. Gothe, K.A. Griffioen, L. Guo, K. Hafidi, H. Hakobyan, C. Hanretty, N. Harrison, D. Heddle, K. Hicks, M. Holtrop, S.M. Hughes, Y. Ilieva, D.G. Ireland, B.S. Ishkhanov, E.L. Isupov, D. Jenkins, H.S. Jo, S. Joosten, D. Keller, G. Khachatryan, M. Khachatryan, M. Khandaker, A. Kim, W. Kim, A. Klein, F.J. Klein, V. Kubarovsky, L. Lanza, P. Lenisa, K. Livingston, I.J.D. MacGregor, N. Markov, B. McKinnon, C.A. Meyer, M. Mirazita, V. Mokeev, R.A. Montgomery, A. Movsisyan, C. Munoz Camacho, G. Murdoch, P. Nadel-Turonski, S. Niccolai, G. Niculescu, I. Niculescu, M. Osipenko, A.I. Ostrovidov, M. Paolone, R. Paremuzyan, K. Park, E. Pasyuk, W. Phelps, S. Pisano, O. Pogorelko, J.W. Price, Y. Prok, D. Protopopescu, B.A. Raue, M. Ripani, A. Rizzo, G. Rosner, P. Roy, F. Sabatié, C. Salgado, R.A. Schumacher, Y.G. Sharabian, Iu. Skorodumina, G.D. Smith, D. Sokhan, N. Sparveris, S. Stepanyan, I.I. Strakovsky, S. Strauch, M. Taiuti, Ye Tian, B. Torayev, M. Ungaro, H. Voskanyan, E. Voutier, N.K. Walford, X. Wei, N. Zachariou, and J. Zhang
Subjects: Physics, QC1-999
Abstract: Measurements of the linearly-polarized photon beam asymmetry Σ for photoproduction from the proton of η and η′ mesons are reported. A linearly-polarized tagged photon beam produced by coherent bremsstrahlung was incident on a cryogenic hydrogen target within the CEBAF Large Acceptance Spectrometer. Results are presented for the γp→ηp reaction for incident photon energies from 1.070 to 1.876 GeV, and from 1.516 to 1.836 GeV for the γp→η′p reaction. For γp→ηp, the data reported here considerably extend the range of measurements to higher energies, and are consistent with the few previously published measurements for this observable near threshold. For γp→η′p, the results obtained are consistent with the few previously published measurements for this observable near threshold, but also greatly expand the incident photon energy coverage for that reaction. Initial analysis of the data reported here with the Bonn–Gatchina model strengthens the evidence for four nucleon resonances – the N(1895)1/2−, N(1900)3/2+, N(2100)1/2+ and N(2120)3/2− resonances – which presently lack the “four-star” status in the current Particle Data Group compilation, providing examples of how these new measurements help refine models of the photoproduction process. Keywords: Meson photoproduction, Eta photoproduction, Eta-prime photoproduction, Polarization observable, Photon beam asymmetry
Published: 2017
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12. Target and double spin asymmetries of deeply virtual π0 production with a longitudinally polarized proton target and CLAS

Author: A. Kim, H. Avakian, V. Burkert, K. Joo, W. Kim, K.P. Adhikari, Z. Akbar, S. Anefalos Pereira, R.A. Badui, M. Battaglieri, V. Batourine, I. Bedlinskiy, A.S. Biselli, S. Boiarinov, P. Bosted, W.J. Briscoe, W.K. Brooks, S. Bültmann, T. Cao, D.S. Carman, A. Celentano, S. Chandavar, G. Charles, T. Chetry, L. Colaneri, P.L. Cole, N. Compton, M. Contalbrigo, O. Cortes, V. Crede, A. D'Angelo, N. Dashyan, R. De Vita, E. De Sanctis, C. Djalali, H. Egiyan, A. El Alaoui, L. El Fassi, P. Eugenio, G. Fedotov, R. Fersch, A. Filippi, J.A. Fleming, A. Fradi, M. Garc con, Y. Ghandilyan, G.P. Gilfoyle, K.L. Giovanetti, F.X. Girod, W. Gohn, E. Golovatch, R.W. Gothe, K.A. Griffioen, L. Guo, K. Hafidi, C. Hanretty, M. Hattawy, D. Heddle, K. Hicks, M. Holtrop, Y. Ilieva, D.G. Ireland, B.S. Ishkhanov, D. Jenkins, H. Jiang, H.S. Jo, S. Joosten, D. Keller, G. Khachatryan, M. Khandaker, A. Klein, F.J. Klein, V. Kubarovsky, S.E. Kuhn, S.V. Kuleshov, L. Lanza, P. Lenisa, H.Y. Lu, I.J.D. MacGregor, N. Markov, P. Mattione, M.E. McCracken, B. McKinnon, V. Mokeev, A. Movsisyan, E. Munevar, P. Nadel-Turonski, L.A. Net, S. Niccolai, M. Osipenko, A.I. Ostrovidov, M. Paolone, K. Park, E. Pasyuk, W. Phelps, S. Pisano, O. Pogorelko, J.W. Price, Y. Prok, M. Ripani, A. Rizzo, G. Rosner, P. Rossi, P. Roy, C. Salgado, R.A. Schumacher, E. Seder, Y.G. Sharabian, Iu. Skorodumina, G.D. Smith, D. Sokhan, N. Sparveris, S. Stepanyan, P. Stoler, I.I. Strakovsky, S. Strauch, V. Sytnik, M. Taiuti, B. Torayev, M. Ungaro, H. Voskanyan, E. Voutier, D.P. Watts, X. Wei, L.B. Weinstein, N. Zachariou, L. Zana, and J. Zhang
Subjects: Nucleon structure, CLAS collaboration, Deeply Virtual Meson Production, Chiral-odd generalized parton distributions, Longitudinally polarized target, Physics, QC1-999
Abstract: The target and double spin asymmetries of the exclusive pseudoscalar channel e→p→→epπ0 were measured for the first time in the deep-inelastic regime using a longitudinally polarized 5.9 GeV electron beam and a longitudinally polarized proton target at Jefferson Lab with the CEBAF Large Acceptance Spectrometer (CLAS). The data were collected over a large kinematic phase space and divided into 110 four-dimensional bins of Q2, xB, −t and ϕ. Large values of asymmetry moments clearly indicate a substantial contribution to the polarized structure functions from transverse virtual photon amplitudes. The interpretation of experimental data in terms of generalized parton distributions (GPDs) provides the first insight on the chiral-odd GPDs H˜T and ET, and complement previous measurements of unpolarized structure functions sensitive to the GPDs HT and E¯T. These data provide a crucial input for parametrizations of essentially unknown chiral-odd GPDs and will strongly influence existing theoretical calculations based on the handbag formalism.
Published: 2017
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13. First measurement of the helicity asymmetry E in η photoproduction on the proton

Author: I. Senderovich, B.T. Morrison, M. Dugger, B.G. Ritchie, E. Pasyuk, R. Tucker, J. Brock, C. Carlin, C.D. Keith, D.G. Meekins, M.L. Seely, D. Rönchen, M. Döring, P. Collins, K.P. Adhikari, D. Adikaram, Z. Akbar, M.D. Anderson, S. Anefalos Pereira, R.A. Badui, J. Ball, N.A. Baltzell, M. Battaglieri, V. Batourine, I. Bedlinskiy, A.S. Biselli, S. Boiarinov, W.J. Briscoe, W.K. Brooks, V.D. Burkert, D.S. Carman, A. Celentano, S. Chandavar, G. Charles, L. Colaneri, P.L. Cole, M. Contalbrigo, O. Cortes, V. Credé, A. D'Angelo, N. Dashyan, R. De Vita, E. De Sanctis, A. Deur, C. Djalali, R. Dupre, H. Egiyan, A. El Alaoui, L. El Fassi, L. Elouadrhiri, P. Eugenio, G. Fedotov, S. Fegan, A. Filippi, J.A. Fleming, A. Fradi, B. Garillon, Y. Ghandilyan, G.P. Gilfoyle, K.L. Giovanetti, F.X. Girod, D.I. Glazier, J.T. Goetz, W. Gohn, E. Golovatch, R.W. Gothe, K.A. Griffioen, M. Guidal, L. Guo, K. Hafidi, H. Hakobyan, C. Hanretty, M. Hattawy, K. Hicks, D. Ho, M. Holtrop, S.M. Hughes, Y. Ilieva, D.G. Ireland, B.S. Ishkhanov, D. Jenkins, H. Jiang, H.S. Jo, K. Joo, S. Joosten, D. Keller, G. Khachatryan, M. Khandaker, A. Kim, F.J. Klein, V. Kubarovsky, M.C. Kunkel, P. Lenisa, K. Livingston, H.Y. Lu, I.J.D. MacGregor, P. Mattione, B. McKinnon, C.A. Meyer, T. Mineeva, V. Mokeev, R.A. Montgomery, A. Movsisyan, C. Munoz Camacho, P. Nadel-Turonski, L.A. Net, S. Niccolai, G. Niculescu, I. Niculescu, M. Osipenko, K. Park, S. Park, P. Peng, W. Phelps, S. Pisano, O. Pogorelko, J.W. Price, Y. Prok, A.J.R. Puckett, M. Ripani, A. Rizzo, G. Rosner, P. Roy, F. Sabatié, C. Salgado, D. Schott, R.A. Schumacher, E. Seder, A. Simonyan, Iu. Skorodumina, G.D. Smith, D.I. Sober, N. Sparveris, S. Stepanyan, P. Stoler, I.I. Strakovsky, S. Strauch, V. Sytnik, Ye Tian, M. Ungaro, H. Voskanyan, E. Voutier, N.K. Walford, X. Wei, M.H. Wood, N. Zachariou, L. Zana, J. Zhang, Z.W. Zhao, and I. Zonta
Subjects: Physics, QC1-999
Abstract: Results are presented for the first measurement of the double-polarization helicity asymmetry E for the η photoproduction reaction γp→ηp. Data were obtained using the FROzen Spin Target (FROST) with the CLAS spectrometer in Hall B at Jefferson Lab, covering a range of center-of-mass energy W from threshold to 2.15 GeV and a large range in center-of-mass polar angle. As an initial application of these data, the results have been incorporated into the Jülich–Bonn model to examine the case for the existence of a narrow N⁎ resonance between 1.66 and 1.70 GeV. The addition of these data to the world database results in marked changes in the predictions for the E observable from that model. Further comparison with several theoretical approaches indicates these data will significantly enhance our understanding of nucleon resonances. Keywords: Eta photoproduction, Polarization observable, Helicity asymmetry
Published: 2016
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14. First measurement of the polarization observable E in the p→(γ→,π+)n reaction up to 2.25 GeV

Author: S. Strauch, W.J. Briscoe, M. Döring, E. Klempt, V.A. Nikonov, E. Pasyuk, D. Rönchen, A.V. Sarantsev, I. Strakovsky, R. Workman, K.P. Adhikari, D. Adikaram, M.D. Anderson, S. Anefalos Pereira, A.V. Anisovich, R.A. Badui, J. Ball, V. Batourine, M. Battaglieri, I. Bedlinskiy, N. Benmouna, A.S. Biselli, J. Brock, W.K. Brooks, V.D. Burkert, T. Cao, C. Carlin, D.S. Carman, A. Celentano, S. Chandavar, G. Charles, L. Colaneri, P.L. Cole, N. Compton, M. Contalbrigo, O. Cortes, V. Crede, N. Dashyan, A. D'Angelo, R. De Vita, E. De Sanctis, A. Deur, C. Djalali, M. Dugger, R. Dupre, H. Egiyan, A. El Alaoui, L. El Fassi, L. Elouadrhiri, P. Eugenio, G. Fedotov, S. Fegan, A. Filippi, J.A. Fleming, T.A. Forest, A. Fradi, N. Gevorgyan, Y. Ghandilyan, K.L. Giovanetti, F.X. Girod, D.I. Glazier, W. Gohn, E. Golovatch, R.W. Gothe, K.A. Griffioen, M. Guidal, L. Guo, K. Hafidi, H. Hakobyan, C. Hanretty, N. Harrison, M. Hattawy, K. Hicks, D. Ho, M. Holtrop, S.M. Hughes, Y. Ilieva, D.G. Ireland, B.S. Ishkhanov, E.L. Isupov, D. Jenkins, H. Jiang, H.S. Jo, K. Joo, S. Joosten, C.D. Keith, D. Keller, G. Khachatryan, M. Khandaker, A. Kim, W. Kim, A. Klein, F.J. Klein, V. Kubarovsky, S.E. Kuhn, P. Lenisa, K. Livingston, H.Y. Lu, I.J.D. MacGregor, N. Markov, B. McKinnon, D.G. Meekins, C.A. Meyer, V. Mokeev, R.A. Montgomery, C.I. Moody, H. Moutarde, A. Movsisyan, E. Munevar, C. Munoz Camacho, P. Nadel-Turonski, L.A. Net, S. Niccolai, G. Niculescu, I. Niculescu, G. O'Rielly, M. Osipenko, A.I. Ostrovidov, K. Park, P. Peng, W. Phelps, J.J. Phillips, S. Pisano, O. Pogorelko, S. Pozdniakov, J.W. Price, S. Procureur, Y. Prok, D. Protopopescu, A.J.R. Puckett, B.A. Raue, M. Ripani, B.G. Ritchie, A. Rizzo, G. Rosner, P. Roy, F. Sabatié, C. Salgado, D. Schott, R.A. Schumacher, E. Seder, M.L. Seely, I. Senderovich, Y.G. Sharabian, A. Simonyan, Iu. Skorodumina, G.D. Smith, D.I. Sober, D. Sokhan, N. Sparveris, P. Stoler, S. Stepanyan, V. Sytnik, M. Taiuti, Ye Tian, A. Trivedi, R. Tucker, M. Ungaro, H. Voskanyan, E. Voutier, N.K. Walford, D.P. Watts, X. Wei, M.H. Wood, N. Zachariou, L. Zana, J. Zhang, Z.W. Zhao, and I. Zonta
Subjects: Baryon spectroscopy, Pion photoproduction, Polarization observables, FROST experiment, Physics, QC1-999
Abstract: First results from the longitudinally polarized frozen-spin target (FROST) program are reported. The double-polarization observable E, for the reaction γ→p→→π+n, has been measured using a circularly polarized tagged-photon beam, with energies from 0.35 to 2.37 GeV. The final-state pions were detected with the CEBAF Large Acceptance Spectrometer in Hall B at the Thomas Jefferson National Accelerator Facility. These polarization data agree fairly well with previous partial-wave analyses at low photon energies. Over much of the covered energy range, however, significant deviations are observed, particularly in the high-energy region where high-L multipoles contribute. The data have been included in new multipole analyses resulting in updated nucleon resonance parameters. We report updated fits from the Bonn–Gatchina, Jülich–Bonn, and SAID groups.
Published: 2015
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15. Measurement of the beam spin asymmetry of e→p→e′p′η in the deep-inelastic regime with CLAS

Author: M. Guidal, C. Djalali, J. A. Tan, A. I. Ostrovidov, K. Park, Z.W. Zhao, G. D. Smith, M. Holtrop, M. Hattawy, D. G. Ireland, Iu. Skorodumina, Volker D. Burkert, K. A. Griffioen, A. S. Biselli, Maxime Defurne, V. Mokeev, D. Marchand, X. Wei, M. Bashkanov, S. Adhikari, V. Crede, Rong Wang, B. McKinnon, P. Lenisa, L. Lanza, Taya Chetry, R. A. Montgomery, C. A. Meyer, N. A. Baltzell, Y. G. Sharabian, P. Chatagnon, M. Ehrhart, W. Kim, D. G. Jenkins, A. Kim, Y. Prok, M. Mirazita, Z. E. Meziani, A. Celentano, R. W. Gothe, R. De Vita, G. Niculescu, Sergey Kuleshov, F. Sabatié, N. Markov, F. X. Girod, V. Batourine, M. Ungaro, N. Dashyan, M. Khachatryan, V. P. Kubarovsky, H. S. Jo, R. Paremuzyan, K. Livingston, O. Pogorelko, L. Barion, G. Rosner, Nicholas M. Harrison, Gerard Gilfoyle, Friedrich Klein, M. Battaglieri, H. Avakian, K. Joo, S. Strauch, H. Hakobyan, D. Sokhan, I. Bedlinskiy, H. Voskanyan, Y. Ghandilyan, Laura Clark, B. S. Ishkhanov, H. Egiyan, Jie Zhang, S. Diehl, C. Salgado, M. Osipenko, K. Hicks, B. Zhao, G. Khachatryan, P. Nadel-Turonski, G. Ciullo, J. P. Ball, S. E. Kuhn, D. S. Carman, Dustin Keller, D. Heddle, Nikos Sparveris, E. De Sanctis, R. A. Schumacher, G. Angelini, P. Eugenio, S. Johnston, L. Guo, Alessandro Rizzo, S. Niccolai, Michael Wood, P. Rossi, C. Munoz Camacho, K. Hafidi, W. J. Briscoe, M. L. Kabir, E. Golovatch, R. Dupre, T. A. Forest, S. Stepanyan, A. Filippi, Avraham Klein, E. L. Isupov, G. Gavalian, I. J. D. MacGregor, M. Contalbrigo, M. Khandaker, I. I. Strakovsky, A. Deur, M. Ripani, S. Boiarinov, M. Taiuti, W. K. Brooks, B. A. Clary, Z. Akbar, Michael Paolone, J. W. Price, A. D'Angelo, D. Protopopescu, E. Voutier, L. El Fassi, A. El Alaoui, Y. Ilieva, Nicholas Zachariou, and P. L. Cole
Subjects: Physics, Nuclear and High Energy Physics, 010308 nuclear & particles physics, Scattering, media_common.quotation_subject, Hadron, Virtual particle, Parton, 01 natural sciences, Asymmetry, Nuclear physics, Pseudoscalar, 0103 physical sciences, Nuclear Experiment, 010306 general physics, Spin-½, media_common, Lepton
Abstract: The beam spin asymmetry of the exclusive pseudoscalar channel e → p → e ′ p ′ η was measured for the first time in the deep-inelastic regime ( W > 2 GeV / c 2 and Q 2 > 1 GeV 2 / c 2 ) using a longitudinally polarized 5.78 GeV electron beam at Jefferson Lab with the CEBAF Large Acceptance Spectrometer. The data were accumulated in 144 four-dimensional bins of Q 2 , x B , − t and ϕ over a wide kinematic range, where ϕ is the azimuthal angle between the lepton and hadron scattering planes, The measured azimuthal dependence with large amplitudes of the sin ⁡ ϕ moments is a clear indication of a substantial contribution to the polarized cross-section from transversely polarized virtual photons. In the framework of generalized parton distributions (GPDs) this contribution is expressed via longitudinal-transverse interference between chiral-even and chiral-odd GPDs. The experimental results are compared to the existing theoretical models demonstrating the sensitivity to the product of chiral-odd and chiral-even GPDs and provide new constraints to the existing GPD parameterizations.
Published: 2019

16. Beam Spin Asymmetry in Semi-Inclusive Electroproduction of Hadron Pairs

Author: K. Park, V. P. Kubarovsky, Krishna Neupane, C. W. Kim, H. Avakian, H. Voskanyan, W. J. Briscoe, Dustin Keller, P. Eugenio, Michael Wood, K. Hafidi, G. Gavalian, L. Marsicano, A Hobart, V. Mokeev, F. X. Girod, R. A. Schumacher, M. Battaglieri, I. I. Strakovsky, R. W. Gothe, T. Chetry, M. J. Amaryan, F. Sabatié, K. Wei, S. Fegan, N. Markov, L. Guo, Alessandro Rizzo, K. A. Griffioen, Fatiha Benmokhtar, Gerard Gilfoyle, R. Paremuzyan, E. L. Isupov, A. Deur, S. Pisano, V. Crede, Ross Milner, O. Soto, P. Lenisa, M. Contalbrigo, C. Dilks, L. Lanza, M. Ungaro, T. A. Forest, C. Mullen, W. K. Brooks, M. Guidal, Z. W. Zhao, S. Stepanyan, N. A. Baltzell, M. Holtrop, T. B. Hayward, Friedrich Klein, Andrea Celentano, O. Pogorelko, J. Poudel, A. Filippi, Brian Raue, K. Hicks, K. Joo, D. Marchand, M. Osipenko, Luciano Pappalardo, K. L. Giovanetti, Hovanes Egiyan, M. Ripani, C. Munoz Camacho, A. D'Angelo, B. Yale, S. Adhikari, L. Venturelli, B. McKinnon, M. Ehrhart, D. G. Ireland, Tim O'Connell, I. Bedlinskiy, D. I. Glazier, W. Phelps, D. G. Jenkins, N. Tyler, M. Leali, L. El Fassi, C. Djalali, Volker D. Burkert, W. Kim, T. Mineeva, D. Heddle, R. De Vita, G. Ciullo, V. Mascagna, H. S. Jo, A. S. Biselli, M. Mirazita, D. Bulumulla, Y. Prok, D. S. Carman, G. Niculescu, B. S. Ishkhanov, E. Pasyuk, Aditya R. Khanal, X. Wei, R. G. Fersch, Andrea Bianconi, H. Atac, P. L. Cole, N. Dashyan, G. Angelini, P. Chatagnon, B. A. Clary, P. Rossi, M. Defurne, Michael Paolone, L. Barion, Axel Schmidt, Aurore Courtoy, K. Livingston, M. Khandaker, Jie Zhang, I. J. D. MacGregor, E. Golovatch, R. Dupre, Y. Ghandilyan, Q. Huang, E. Voutier, A. Vossen, A. El Alaoui, Y. Ilieva, Nicholas Zachariou, J. C. Carvajal, S. Strauch, D. P. Watts, F. Bossu, Nikolaos Sparveris, Dinko Pocanic, S. E. Kuhn, M. Hattawy, Y. G. Sharabian, S. Boiarinov, H. Hakobyan, J. Ritman, S. Diehl, C. Salgado, U. Shrestha, Institut de Recherches sur les lois Fondamentales de l'Univers (IRFU), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay, Laboratoire de Physique des 2 Infinis Irène Joliot-Curie (IJCLab), Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), and CLAS
Subjects: High Energy Physics::Lattice, Nuclear Theory, Hadron, parton: distribution function, General Physics and Astronomy, Parton, 01 natural sciences, High Energy Physics - Experiment, High Energy Physics - Experiment (hep-ex), Economica, higher-twist, [PHYS.HEXP]Physics [physics]/High Energy Physics - Experiment [hep-ex], Nuclear Experiment (nucl-ex), electron: beam, Nuclear Experiment, dimension: 1, Physics, Quantum chromodynamics, deep inelastic scattering: semi-inclusive reaction, Settore FIS/04, nucleon, kinematics, Quarks and Gluons, helicity distributions, quark: valence, Nucleon, Jefferson Lab, Quark, Particle physics, polarization: longitudinal, FOS: Physical sciences, Socio-culturale, [PHYS.NEXP]Physics [physics]/Nuclear Experiment [nucl-ex], Transversity Distributions, hadron: electroproduction, hadron: pair production, Pion, CLAS, Hadron Physics, quantum chromodynamics, 0103 physical sciences, ddc:530, 010306 general physics, High Energy Physics::Phenomenology, Ambientale, Deep inelastic scattering, spin: asymmetry: measured, Distribution function, Elementary Particles and Fields, QCD Dynamics, High Energy Physics::Experiment, pi: pair production, experimental results
Abstract: Physical review letters 126(6), 062002 (2021). doi:10.1103/PhysRevLett.126.062002, Published by APS, College Park, Md.
Published: 2021

17. Photoproduction of η mesons off the proton for 1.2<Eγ<4.7GeV using CLAS at Jefferson Laboratory

Author: I. Illari, R. A. Schumacher, U. Shrestha, M. Leali, S. Adhikari, B. McKinnon, C. A. Meyer, E. Munevar, P. Chatagnon, B. S. Ishkhanov, Aditya R. Khanal, G. V. Fedotov, P. Lenisa, J. Ritman, S. Stepanyan, N. Dashyan, D. P. Watts, Andrea Bianconi, M. Ungaro, K. P. Adhikari, A. El Alaoui, I. I. Strakovsky, G. Rosner, T. Chetry, A. Deur, C. W. Kim, Laura Clark, W. Phelps, M. Battaglieri, Nicholas Zachariou, J. C. Carvajal, Alexander Schmidt, M. J. Amaryan, William Brooks, Yordanka Ilieva, T. B. Hayward, V. Mascagna, B. A. Clary, E. L. Isupov, Y. G. Sharabian, H. Voskanyan, Friedrich Klein, W. J. Briscoe, P. Eugenio, S. Boiarinov, Brian Raue, G. Angelini, L. Barion, K. Joo, M. Guidal, Michael Paolone, Z. W. Zhao, F. X. Girod, F. Bossu, R. Cruz-Torres, E. Golovatch, M. Holtrop, R. Dupre, S. Strauch, Hovanes Egiyan, Maxime Defurne, K. A. Griffioen, Dustin Keller, C. Munoz Camacho, H. Hakobyan, Y. Prok, H. S. Jo, M. Hattawy, Michael Wood, K. Hafidi, D. G. Ireland, Luciano Pappalardo, V. Crede, A. Kim, D. I. Glazier, G. Ciullo, D. S. Carman, F. Sabatié, T. Hu, R. Paremuzyan, R. De Vita, D. Marchand, D. Protopopescu, Eugene Pasyuk, X. Wei, L. Venturelli, S. Diehl, Fatiha Benmokhtar, O. Soto, C. Salgado, E. Voutier, L. Lanza, Nicholas M. Harrison, Gerard Gilfoyle, A. Filippi, A. Movsisyan, J. W. Price, D. Sokhan, V. P. Kubarovsky, I. Bedlinskiy, M. Khandaker, M. Khachatryan, Nikolaos Sparveris, Z. E. Meziani, K. Wei, S. Niccolai, K. Livingston, N. Markov, Iu. Skorodumina, N. Tyler, C. Djalali, J. A. Tan, V. I. Mokeev, D. Heddle, Jie Zhang, G. Gavalian, D. G. Jenkins, R. Fersch, M. Ehrhart, M. Ripani, O. Pogorelko, P. L. Cole, J. Rowley, Tim O'Connell, A. I. Ostrovidov, Michael Dugger, T. Mineeva, P. Nadel-Turonski, H. Atac, A. S. Biselli, A. D'Angelo, L. Guo, Sylvester Joosten, Alessandro Rizzo, G. Asryan, L. El Fassi, C. Ayerbe Gayoso, M. E. McCracken, A. Hobart, C. Hanretty, W. Kim, G. Niculescu, P. Stoler, M. Osipenko, I. J. D. MacGregor, K. Hicks, M. Contalbrigo, J. Poudel, Z. Akbar, A. Celentano, and R. W. Gothe
Subjects: Physics, Particle physics, Range (particle radiation), Photon, Proton, Meson, 010308 nuclear & particles physics, Sigma, Photon energy, 01 natural sciences, 7. Clean energy, Resonance (particle physics), 0103 physical sciences, High Energy Physics::Experiment, Nuclear Experiment, 010306 general physics, Nucleon
Abstract: Photoproduction cross sections are reported for the reaction $\gamma p\to p\eta$ using energy-tagged photons and the CLAS spectrometer at Jefferson Laboratory. The $\eta$ mesons are detected in their dominant charged decay mode, $\eta\to \pi^+\pi^-\pi^0$, and results on differential cross sections are presented for incident photon energies between 1.2 and 4.7 GeV. These new $\eta$ photoproduction data are consistent with earlier CLAS results but extend the energy range beyond the nucleon resonance region into the Regge regime. The normalized angular distributions are compared with the experimental results from several other experiments, and with predictions of $\eta$ MAID\,2018 and the latest solution of the Bonn-Gatchina coupled-channel analysis. Differential cross sections $d\sigma/dt$ are presented for incident photon energies $E_\gamma > 2.9$ GeV ($W > 2.5$ GeV), and compared with predictions which are based on Regge trajectories exchange in the $t$-channel (Regge models). The data confirm the expected dominance of $\rho$, $\omega$ vector-meson exchange in an analysis by the Joint Physics Analysis Center.
Published: 2020

18. Extraction of beam-spin asymmetries from the hard exclusive π+ channel off protons in a wide range of kinematics

Author: Y. G. Sharabian, K. Tezgin, S. E. Kuhn, M. Hattawy, S. Adhikari, M. Khachatryan, M. J. Amaryan, N. Tyler, P. Lenisa, C. Dilks, J. A. Tan, C. W. Kim, H. Avakian, B. McKinnon, Maxime Defurne, Laura Clark, K. A. Griffioen, Chaden Djalali, D. Bulumulla, T. Mineeva, L. Guo, G. Angelini, D. I. Glazier, B. S. Ishkhanov, S. Strauch, Aditya R. Khanal, F. X. Girod, T. B. Hayward, M. Guidal, D. P. Watts, K. L. Giovanetti, P. L. Cole, E. L. Isupov, E. Golovatch, G. Asryan, L. Lanza, R. De Vita, Alessandro Rizzo, Z. W. Zhao, V. Crede, R. Dupre, H. Voskanyan, Andrea Bianconi, N. Markov, Brian Raue, Y. Ghandilyan, S. Boiarinov, A. D'Angelo, M. Mirazita, M. Ehrhart, W. Phelps, W. J. Briscoe, A. Filippi, M. Holtrop, Victor Mokeev, U. Shrestha, L. El Fassi, H. Atac, P. Nadel-Turonski, M. Khandaker, Luciano Pappalardo, P. Eugenio, J. W. Price, O. Pogorelko, I. J. D. MacGregor, T. Chetry, M. Osipenko, J. Rowley, M. Ripani, Fatiha Benmokhtar, H. Hakobyan, O. Soto, M. Battaglieri, S. Diehl, Paolo Rossi, K. Park, Michael Paolone, A. Celentano, R. W. Gothe, D. Heddle, F. Bossu, D. G. Ireland, Hovanes Egiyan, C. Munoz Camacho, W. Kim, Axel Schmidt, G. Niculescu, P. Stoler, Volker D. Burkert, M. Contalbrigo, A. S. Biselli, M. Ungaro, I. I. Strakovsky, K. Hicks, A. Deur, Nicholas M. Harrison, Gerard Gilfoyle, D. Marchand, V. Mascagna, Eugene Pasyuk, W. K. Brooks, D. G. Jenkins, S. Joosten, L. Marsicano, V. P. Kubarovsky, K. P. Adhikari, M. Leali, D. Riser, Z. E. Meziani, Y. Prok, F. Sabatié, I. Bedlinskiy, P. Kroll, K. Joo, Dustin Keller, Michael Wood, A. Kim, K. Livingston, Jie Zhang, H. S. Jo, C. Salgado, A. El Alaoui, Y. Ilieva, P. Chatagnon, Nicholas Zachariou, J. C. Carvajal, K. Semenov-Tian-Shansky, N. Dashyan, E. Voutier, L. Venturelli, L. Barion, R. A. Schumacher, G. Ciullo, D. S. Carman, Nikos Sparveris, X. Wei, T. A. Forest, S. Stepanyan, Institut de Recherches sur les lois Fondamentales de l'Univers (IRFU), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay, Laboratoire de Physique des 2 Infinis Irène Joliot-Curie (IJCLab), Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), and CLAS
Subjects: Particle physics, generalized parton distribution, Partons, Nucleons, Compton Scattering, media_common.quotation_subject, General Physics and Astronomy, parton: distribution function, Socio-culturale, Parton, [PHYS.NEXP]Physics [physics]/Nuclear Experiment [nucl-ex], 01 natural sciences, Resonance (particle physics), Asymmetry, High Energy Physics - Experiment, Pion, PE2_2, PE2_1, CLAS, 0103 physical sciences, [PHYS.HEXP]Physics [physics]/High Energy Physics - Experiment [hep-ex], 010306 general physics, Nuclear Experiment, PE2_3, Spin-½, media_common, Physics, Settore FIS/04, electroproduction, moment, Moment (mathematics), distribution amplitude, High Energy Physics - Phenomenology, Amplitude, kinematics, [PHYS.HPHE]Physics [physics]/High Energy Physics - Phenomenology [hep-ph], Elementary Particles and Fields, High Energy Physics::Experiment, Center of mass, asymmetry, experimental results
Abstract: We have measured beam-spin asymmetries to extract the \ud sin\ud ϕ\ud moment \ud A\ud sin\ud ϕ\ud L\ud U\ud from the hard exclusive \ud →\ud e\ud p\ud →\ud e\ud ′\ud n\ud π\ud +\ud reaction above the resonance region, for the first time with nearly full coverage from forward to backward angles in the center of mass. The \ud A\ud sin\ud ϕ\ud L\ud U\ud moment has been measured up to \ud 6.6\ud \ud \ud GeV\ud 2\ud in \ud −\ud t\ud , covering the kinematic regimes of generalized parton distributions (GPD) and baryon-to-meson transition distribution amplitudes (TDA) at the same time. The experimental results in very forward kinematics demonstrate the sensitivity to chiral-odd and chiral-even GPDs. In very backward kinematics where the TDA framework is applicable, we found \ud A\ud sin\ud ϕ\ud L\ud U\ud to be negative, while a sign change was observed near 90° in the center of mass. The unique results presented in this Letter will provide critical constraints to establish reaction mechanisms that can help to further develop the GPD and TDA frameworks.
Published: 2020

19. First measurement of direct photoproduction of the a2(1320)0 meson on the proton

Author: J. Rowley, A. I. Ostrovidov, Volker D. Burkert, A. S. Biselli, W. Phelps, K. A. Griffioen, V. Mascagna, N. Markov, M. E. McCracken, A. Hobart, Carlos A. Salgado, A. Filippi, A. Pilloni, Frank Klein, Dustin Keller, P. Eugenio, L. Marsicano, Sylvester Joosten, Maxime Defurne, M. Khandaker, M. Khachatryan, M. Osipenko, Pawel Nadel-Turonski, Michael Paolone, Alexander Schmidt, D. I. Glazier, D. Bulumulla, E. Munevar, B. S. Ishkhanov, Aditya R. Khanal, Nikolaos Sparveris, M. Ungaro, K. Hafidi, F. Bossu, M. Guidal, G. Niculescu, L. Lanza, D. G. Jenkins, I. J. D. MacGregor, R. De Vita, M. Leali, Laura Clark, M. J. Amaryan, Andrea Bianconi, C. W. Kim, W. Kim, W. Gohn, F. X. Girod, N. Tyler, C. Djalali, J. A. Tan, P. Chatagnon, G. V. Fedotov, H. Voskanyan, A. D'Angelo, T. Chetry, I. Bedlinskiy, L. Elouadrhiri, M. Holtrop, F. Hauenstein, W. J. Briscoe, E. Pasyuk, S. Strauch, K. Joo, H. Atac, D. P. Watts, H. Egiyan, G. Angelini, L. El Fassi, I. I. Strakovsky, R. Dupre, M. Battaglieri, F. Sabatié, Luciano Pappalardo, D. Heddle, A. Deur, M. Ripani, G. Gavalian, V. Mokeev, D. Marchand, V. Lucherini, V. P. Kubarovsky, Michael Dugger, Fatiha Benmokhtar, Krishna Neupane, R. G. Fersch, O. Pogorelko, O. Soto, S. Niccolai, Vincent Mathieu, P. L. Cole, Z. W. Zhao, Alessandro Rizzo, E. Golovatch, P. Lenisa, K. Hicks, M. Ehrhart, S. Adhikari, T. B. Hayward, J. Zhang, M. Hattawy, J. W. Price, N. Dashyan, Yordanka Ilieva, L. Barion, G. Rosner, William Brooks, G. Ciullo, Y. Prok, L. Venturelli, D. S. Carman, R. A. Schumacher, A. El Alaoui, X. Wei, Nicholas Zachariou, J. C. Carvajal, S. Stepanyan, E. Voutier, A. Movsisyan, Adam P. Szczepaniak, D. Sokan, Z. E. Meziani, K. Livingston, K. P. Adhikari, H. Hakobyan, H. S. Jo, A. Kim, J. Ritman, S. Diehl, D. G. Ireland, V. Crede, O. Cortes, E. L. Isupov, R. Paremuzyan, S. Boiarinov, R. Cruz-Torres, Nicholas M. Harrison, U. Shrestha, M. Contalbrigo, C. Munoz Camacho, M. H. Wood, B. McKinnon, A. Celentano, R. W. Gothe, M. Mirazita, and N. Gevorgyan
Subjects: Physics, Meson, 010308 nuclear & particles physics, Partial wave analysis, Hadron, Sigma, Photon energy, 01 natural sciences, Nuclear physics, Amplitude, 0103 physical sciences, Invariant mass, Nuclear Experiment, 010306 general physics, Phenomenology (particle physics)
Abstract: We present the first measurement of the exclusive reaction $\gamma p \rightarrow a_2(1320)^0 \, p$ in the photon energy range $3.5$-$5.5$ GeV and four-momentum transfer squared $0.2
Published: 2020

20. Evidence for the N′(1720)3/2+ nucleon resonance from combined studies of CLAS π+π−p photo- and electroproduction data

Author: R. W. Gothe, B. S. Ishkhanov, K. Joo, D. S. Carman, Latifa Elouadrhiri, Arjun Trivedi, E. Golovatch, Eugene Pasyuk, N. Markov, V. I. Mokeev, Volker D. Burkert, K. Hicks, and E. L. Isupov
Subjects: Hadronic decay, Physics, Nuclear and High Energy Physics, Range (particle radiation), 010308 nuclear & particles physics, Hadron, Resonance couplings, Resonance, State (functional analysis), Missing resonances, 01 natural sciences, Two pion production, lcsh:QC1-999, Nuclear physics, Baryon, High Energy Physics - Phenomenology, Amplitude, 0103 physical sciences, 010306 general physics, Nucleon, Nuclear Experiment, lcsh:Physics
Abstract: The analysis of the nine 1-fold differential cross sections for the $\gamma_{r,v} p \to \pi^+\pi^-p$ photo- and electroproduction reactions obtained with the CLAS detector at Jefferson Laboratory was carried out with the goal to establish the contributing resonances in the mass range from 1.6~GeV to 1.8~GeV. In order to describe the photo- and electroproduction data with $Q^2$-independent resonance masses and hadronic decay widths in the $Q^2$ range below 1.5~GeV$^2$, it was found that an $N'(1720)3/2^+$ state is required in addition to the already well-established nucleon resonances. This work demonstrates that the combined studies of $\pi^+\pi^-p$ photo- and electroproduction data are vital for the observation of this resonance. The contributions from the $N'(1720)3/2^+$ state and the already established $N(1720)3/2^+$ state with a mass of 1.745~GeV are well separated by their different hadronic decays to the $\pi \Delta$ and $\rho p$ final states and the different $Q^2$-evolution of their photo-/electroexcitation amplitudes. The $N'(1720)3/2^+$ state is the first recently established baryon resonance for which the results on the $Q^2$-evolution of the photo-/electrocouplings have become available. These results are important for the exploration of the nature of the ``missing'' baryon resonances., Comment: accepted for publication in Phys. Lett. B
Published: 2020

21. Exclusive π0p electroproduction off protons in the resonance region at photon virtualities 0.4GeV2≤Q2≤1GeV2

Author: P. Eugenio, M. Taiuti, Carlos A. Salgado, L. C. Smith, I. I. Strakovsky, B. S. Ishkhanov, R. Dupre, M. Battaglieri, Aditya R. Khanal, A. Deur, R. A. Schumacher, M. Contalbrigo, Michael Paolone, F. Bossu, C. Evans, Maxime Defurne, N. Tyler, C. Djalali, J. A. Tan, K. A. Griffioen, Pawel Nadel-Turonski, Fatiha Benmokhtar, O. Soto, R. De Vita, M. Ungaro, S. Niccolai, L. Lanza, A. D'Angelo, A. Kim, Alessandro Rizzo, T. Mineeva, S. Stepanyan, W. Kim, U. Shrestha, V. Crede, L. El Fassi, T. B. Hayward, H. Atac, R. Paremuzyan, P. Stoler, K. Joo, D. G. Jenkins, M. Leali, K. Hicks, G. Ciullo, William Brooks, N. Markov, M. Guidal, G. Niculescu, Y. Prok, L. Venturelli, W. Phelps, E. De Sanctis, V. Mascagna, I. Bedlinskiy, E. Golovatch, D. S. Carman, A. Celentano, R. W. Gothe, E. L. Isupov, M. Holtrop, Nikos Sparveris, C. W. Kim, Luciano Pappalardo, X. Wei, F. X. Girod, S. Boiarinov, G. Angelini, H. Avakian, J. W. Price, P. L. Cole, G. Rosner, N. A. Baltzell, T. Chetry, J. Rowley, K. Park, D. Sokhan, Y. Ghandilyan, F. Sabatié, Y. G. Sharabian, H. Hakobyan, H. S. Jo, E. Voutier, S. Diehl, D. G. Ireland, I. J. D. MacGregor, N. Dashyan, Volker D. Burkert, A. S. Biselli, S. Strauch, S. Adhikari, M. H. Wood, M. Osipenko, P. Chatagnon, B. McKinnon, Yordanka Ilieva, V. Mokeev, M. Mirazita, Rong Wang, M. Ehrhart, L. Barion, M. Hattawy, H. Voskanyan, S. K. Nanda, M. Ripani, M. Khachatryan, W. J. Briscoe, D. Marchand, E. Pasyuk, V. P. Kubarovsky, D. Riser, A. El Alaoui, C. Ayerbe Gayoso, Nicholas Zachariou, J. C. Carvajal, O. Pogorelko, D. Protopopescu, Frank Klein, Dustin Keller, K. Livingston, K. Hafidi, M. J. Amaryan, A. Filippi, and M. Khandaker
Subjects: Physics, Range (particle radiation), Photon, Proton, 010308 nuclear & particles physics, Resonance, 01 natural sciences, Nuclear physics, Cross section (physics), Isospin, 0103 physical sciences, Invariant mass, 010306 general physics, Legendre polynomials
Abstract: The exclusive electroproduction process ep→e′p′π0 was measured in the range of photon virtualities Q2=0.4–1.0GeV2 and the invariant mass range of the pπ0 system of W=1.1–1.8 GeV. These kinematics are covered in exclusive π0 electroproduction off the proton with nearly complete angular coverage in the pπ0 center-of-mass system and with high statistical accuracy. Nearly 36 000 cross-section points were measured, and the structure functions σT+eσL,σLT, and σTT, were extracted via fitting the ϕπ0 dependence of the cross section. A Legendre polynomial expansion analysis demonstrates the sensitivity of our data to high-lying N* and Δ* resonances with M>1.6 GeV. As part of a broad effort to determine the electrocouplings of the N* and Δ* resonances using both single- and double-pion electroproduction, this dataset is crucial for the reliable extraction of the high-lying resonance electrocouplings from the combined isospin analysis of the Nπ and π+π−p channels.
Published: 2020

22. Beam–target helicity asymmetry $E$ in $K^+$ $\Sigma^-$ photoproduction on the neutron

Author: R. De Vita, D. Marchand, H. Atac, H. S. Jo, A. Filippi, L. Marsicano, N. K. Walford, O. Soto, M. Khandaker, I. J. D. MacGregor, K. Hicks, W. Phelps, R. A. Schumacher, Michael Paolone, H. Hakobyan, W. Kim, G. Charles, F. Bossu, H. Lu, S. Joosten, J. W. Price, S. Diehl, C. Salgado, William Brooks, L. Venturelli, D. Heddle, V. P. Kubarovsky, I. Bedlinskiy, Z. E. Meziani, V. Mascagna, A. Celentano, R. W. Gothe, N. Markov, Alessandro Rizzo, W. Gohn, G. Asryan, Axel Schmidt, Dustin Keller, M. Ungaro, M. Guidal, M. Contalbrigo, M. Osipenko, Z. W. Zhao, Fatiha Benmokhtar, E. L. Isupov, Y. Prok, J. Poudel, O. Pogorelko, A. I. Ostrovidov, K. Park, M. J. Amaryan, Michael Wood, K. Hafidi, M. Holtrop, M. Ehrhart, C.D. Bass, V. A. Nikonov, A. D'Angelo, D. G. Jenkins, D. G. Ireland, G. Rosner, S. Boiarinov, E. Golovatch, P. Eugenio, K. Livingston, Luciano Pappalardo, K. Joo, M. Leali, Jie Zhang, T. Kageya, Volker D. Burkert, Y. Ghandilyan, A. S. Biselli, C. W. Kim, G. Gavalian, U. Shrestha, F.-X. Girod, Gerard Gilfoyle, M. Ripani, R. G. Fersch, H. Voskanyan, A. El Alaoui, G. Angelini, Nicholas Zachariou, J. C. Carvajal, W. J. Briscoe, P. L. Cole, T. Chetry, N. Gevorgyan, D. Ho, I. I. Strakovsky, A. M. Sandorfi, A. Deur, Victor Mokeev, D. Sokhan, T. R. O'Connell, Chaden Djalali, P. Nadel Turonski, T. Mineeva, M. Bashkanov, S. Adhikari, D. Bulumulla, E. Munevar, B. McKinnon, B. S. Ishkhanov, Aditya R. Khanal, Andrea Bianconi, I. Zonta, X. Wei, P. Peng, Hovanes Egiyan, C. Munoz Camacho, P. Lenisa, M. Hattawy, J. A. Fleming, Friedrich Klein, Brian Raue, Andrew Puckett, E. Voutier, Martin K. Mayer, M. Khachatryan, K. A. Griffioen, Nikolaos Sparveris, K. P. Adhikari, C. S. Whisnant, C. Hanretty, L. Lanza, R. Dupre, M. Battaglieri, M. Lowry, S. Strauch, Eugene Pasyuk, N. Dashyan, Yordanka Ilieva, L. Barion, G. Ciullo, D. S. Carman, S. Fegan, D. P. Watts, A. V. Sarantsev, N. Tyler, J. A. Tan, P. Chatagnon, Institut de Recherches sur les lois Fondamentales de l'Univers (IRFU), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay, Laboratoire de Physique des 2 Infinis Irène Joliot-Curie (IJCLab), Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), and CLAS
Subjects: Nuclear and High Energy Physics, Socio-culturale, nucleon resonance, Nucleons, Photoproduction, Mesons, [PHYS.NEXP]Physics [physics]/Nuclear Experiment [nucl-ex], 01 natural sciences, K+: photoproduction, Particle identification, Nuclear physics, chemistry.chemical_compound, PE2_2, PE2_1, CLAS, 0103 physical sciences, Neutron, Hydrogen deuteride, n: target, 010306 general physics, Nuclear Experiment, PE2_3, photon: beam, Physics, 010308 nuclear & particles physics, nucleus: target, Settore FIS/04, Resonance, helicity: asymmetry, Observable, Sigma-: photoproduction, Helicity, lcsh:QC1-999, chemistry, Excited state, spectrometer, Nucleon, lcsh:Physics, Jefferson Lab, experimental results
Abstract: We report a measurement of a beam–target double-polarisation observable (E) for the γ→n→(p)→K+Σ−(p) reaction. The data were obtained impinging the circularly-polarised energy-tagged photon beam of Hall B at Jefferson Lab on a longitudinally-polarised frozen-spin hydrogen deuteride (HD) nuclear target. The E observable for an effective neutron target was determined for centre-of-mass energies 1.70≤W≤2.30 GeV, with reaction products detected over a wide angular acceptance by the CLAS spectrometer. These new double-polarisation data give unique constraints on the strange decays of excited neutron states. Inclusion of the new data within the Bonn-Gatchina theoretical model results in significant changes for the extracted photocouplings of a number of established nucleon resonances. Possible improvements in the PWA description of the experimental data with additional “missing” resonance states, including the N(2120)3/2− resonance, are also quantified.
Published: 2020

23. The CLAS12 Spectrometer at Jefferson Laboratory

Author: C. W. Kim, H. Avakian, D. Protopopescu, D. Heddle, M. Contalbrigo, M. L. Kabir, H. Voskanyan, E. Voutier, T. Chetry, M. Zarecky, J. Poudel, I. Illari, B. A. Clary, M. Osipenko, D. Insley, D. P. Watts, I. Bedlinskiy, Michael Paolone, V. Sergeyeva, D. Kashy, M. Khachatryan, F. Hauenstein, V. Mascagna, Nikolaos Sparveris, F. Bossu, D. Marchand, W. Kim, G. Niculescu, P. Bonneau, G. Charles, P. Hemler, Ruben J. Fair, P. Moran, Dustin Keller, C. Ayerbe Gayoso, Nicholas Zachariou, M. Ungaro, C. Munoz Camacho, M. J. Amaryan, G. Rosner, I. J. D. MacGregor, T. A. Forest, V. Lucherini, S. E. Kuhn, Y. Prok, M. Hattawy, S. Stepanyan, Michael Wood, K. Hafidi, M. D. Mestayer, S. Lee, M. Wiseman, F. Sabatié, R. Paremuzyan, N. Dashyan, A. Deur, K. Hicks, K. Joo, E. L. Isupov, N. A. Baltzell, R. W. Gothe, S. Christo, L. C. Smith, B. S. Ishkhanov, Latifa Elouadrhiri, V. Baturin, Nicholas M. Harrison, Gerard Gilfoyle, M. McMullen, G. E. Dodge, H. S. Jo, R. Johnston, A. Yegneswaran, K. Livingston, A. Lung, P. Stoler, M. Guidal, D. Sokhan, K. Price, Aditya R. Khanal, K. P. Adhikari, Jie Zhang, K. Bruhwel, S. Adhikari, S. Boyarinov, B. McKinnon, M. Ehrhart, M. Leali, Z. W. Zhao, S. Joosten, B. J. Roy, V. P. Kubarovsky, J. Newton, P. Chatagnon, G. V. Fedotov, D. Tilles, M.A. Antonioli, Renuka Rajput-Ghoshal, G. D. Smith, M. Holtrop, C. Cuevas, V. Gyurjyan, Probir K. Ghoshal, Yordanka Ilieva, H. Hakobyan, Alexander Schmidt, Luciano Pappalardo, Andrea Bianconi, W. J. Briscoe, M. Turisini, M. Mirazita, D. I. Glazier, M. Garçon, M. Ripani, F. X. Girod, A. Filippi, K. L. Giovanetti, R. Miller, J. Ritman, S. Diehl, R. De Vita, C. D. Keith, Y. G. Sharabian, M. Lowry, M. Defurne, E. Pasyuk, P. Naidoo, J. Hogan, N. Markov, Or Hen, C. Salgado, M. Taylor, G. Young, S. Strauch, Larry Weinstein, H. Atac, Chaden Djalali, A. Hobart, A. Kim, Z. E. Meziani, S. Schadmand, U. Shrestha, T. Ewing, T. Mineeva, O. Pogorelko, S. Nanda, L. Barion, G. Angelini, J. Rowley, P. Rossi, M. Leffel, William Brooks, I. Mandjavidze, L. Venturelli, Iu. Skorodumina, Y. Gotra, C. Mealer, J. W. Price, S. Aune, C. Wiggins, D. G. Ireland, G. Gavalian, G. Jacobs, V. Crede, Volker D. Burkert, A. S. Biselli, O. Pastor, Victor Mokeev, E.P. Segarra, Ross Milner, N. Tyler, J. A. Tan, E. Golovatch, R. Dupre, W. Phelps, Andrea Celentano, S. Procureur, M. Cook, G. Ciullo, M. Battaglieri, D. S. Carman, B. Raydo, A. Rizzo, X. Wei, R. Cruz-Torres, S. Niccolai, K. A. Griffioen, B. Eng, A. Movsisyan, P. L. Cole, L. Lanza, G. Christiaens, A. D'Angelo, T. Kageya, L. El Fassi, P. Lenisa, V. Ziegler, C. Hanretty, D. Anderson, T. B. Hayward, Brian Raue, Fatiha Benmokhtar, O. Soto, Institut de Recherches sur les lois Fondamentales de l'Univers (IRFU), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay, Institut de Physique Nucléaire d'Orsay (IPNO), Centre National de la Recherche Scientifique (CNRS)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Université Paris-Sud - Paris 11 (UP11), and Université Paris-Sud - Paris 11 (UP11)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS)
Subjects: Physics::Instrumentation and Detectors, data acquisition, magnet: solenoid, superconductivity: torus, Solenoid, 01 natural sciences, Particle identification, Luminosity, momentum resolution, electron: beam, Nuclear Experiment, Instrumentation, QC, Physics, Luminosity (scattering theory), Settore FIS/04, Detector, Magnetic spectrometer, magnet: torus, performance, Nuclear and High Energy Physics, Meson, vertex detector, nucleon: interaction, CLAS12, Electromagnetic physics, Large acceptance, Socio-culturale, fabrication, beam: energy, Nuclear physics, PE2_1, CLAS, 0103 physical sciences, [PHYS.PHYS.PHYS-INS-DET]Physics [physics]/Physics [physics]/Instrumentation and Detectors [physics.ins-det], 010306 general physics, PE2_3, scintillation counter, Cherenkov radiation, detector: design, activity report, Spectrometer, 010308 nuclear & particles physics, nucleus, CLAS12, Electromagnetic physics, Large acceptance, Luminosity, Magnetic spectrometer, magnet: superconductivity, magnetic spectrometer, electromagnetic physics, large acceptance, luminosity, neutral particle, Automatic Keywords, calorimeter: electromagnetic, Cherenkov counter, spectrometer, particle identification, Beam (structure)
Abstract: International audience; The CEBAF Large Acceptance Spectrometer for operation at 12 GeV beam energy (CLAS12) in Hall B at Jefferson Laboratory is used to study electro-induced nuclear and hadronic reactions. This spectrometer provides efficient detection of charged and neutral particles over a large fraction of the full solid angle. CLAS12 has been part of the energy-doubling project of Jefferson Lab’s Continuous Electron Beam Accelerator Facility, funded by the United States Department of Energy. An international collaboration of 48 institutions contributed to the design and construction of detector hardware, developed the software packages for the simulation of complex event patterns, and commissioned the detector systems. CLAS12 is based on a dual-magnet system with a superconducting torus magnet that provides a largely azimuthal field distribution that covers the forward polar angle range up to 35 ∘ , and a solenoid magnet and detector covering the polar angles from 35° to 125° with full azimuthal coverage. Trajectory reconstruction in the forward direction using drift chambers and in the central direction using a vertex tracker results in momentum resolutions of < 1% and < 3%, respectively. Cherenkov counters, time-of-flight scintillators, and electromagnetic calorimeters provide good particle identification. Fast triggering and high data-acquisition rates allow operation at a luminosity of 1035 cm −2 s −1 . These capabilities are being used in a broad program to study the structure and interactions of nucleons, nuclei, and mesons, using polarized and unpolarized electron beams and targets for beam energies up to 11 GeV. This paper gives a general description of the design, construction, and performance of CLAS12.
Published: 2020

24. Semi-inclusive π0 target and beam-target asymmetries from 6 GeV electron scattering with CLAS

Author: P. Lenisa, W. Kim, R. Dupre, M. Battaglieri, G. Niculescu, G. Rosner, K. Livingston, M. Hattawy, Friedrich Klein, Y. Ghandilyan, A. Filippi, X. Wei, Brian Raue, M. Khandaker, M. J. Amaryan, V. I. Mokeev, D. Heddle, K. L. Giovanetti, Larry Weinstein, G. Hollis, R. A. Schumacher, Jie Zhang, K. A. Griffioen, Dustin Keller, C. Hanretty, N. Guler, G. Khachatryan, A. Celentano, R. W. Gothe, D. P. Watts, P. Nadel-Turonski, Michael Wood, Taya Chetry, W. J. Briscoe, H. Egiyan, M. Ungaro, Laura Clark, L. Lanza, S. Bültmann, M. E. McCracken, Sergey Kuleshov, K. P. Adhikari, T. A. Forest, C. Carlin, H. Avakian, F. X. Girod, S. Pisano, B. S. Ishkhanov, Sylvester Joosten, P. Eugenio, F. Cao, P. Bosted, P. Rossi, S. Strauch, D. Adikaram, E. De Sanctis, M. Guidal, M. Taiuti, J. Brock, C. Munoz Camacho, K. Joo, H. Hakobyan, D. Protopopescu, G. D. Smith, M. Holtrop, W. Phelps, V. Crede, C. Salgado, D. I. Sober, M. Garçon, J. Pierce, E. Voutier, S. Adhikari, B. McKinnon, Avraham Klein, R. A. Montgomery, C. Djalali, H. Voskanyan, Maxime Defurne, I. Bedlinskiy, L. Colaneri, O. Cortes, M. Mirazita, E. Phelps, H. Y. Lu, E. L. Isupov, E. Pasyuk, V. Batourine, R. De Vita, A. El Alaoui, S. Boiarinov, Nicholas Zachariou, A. D'Angelo, R. Paremuzyan, S. Anefalos Pereira, Nicholas M. Harrison, Gerard Gilfoyle, A. Kim, D. Sokhan, N. Markov, N. A. Baltzell, L. El Fassi, J. W. Price, I. Niculescu, V. P. Kubarovsky, Z. W. Zhao, K. Hicks, D. Riser, C. D. Keith, A. I. Ostrovidov, L. Guo, Alessandro Rizzo, O. Pogorelko, S. M. Hughes, K. Park, G. Ddoge, D. G. Ireland, I. Stankovic, T. Mineeva, H. Jiang, R. G. Fersch, Volker D. Burkert, A. S. Biselli, William Brooks, P. L. Cole, S. Koirala, A. Fradi, M. Osipenko, M. Contalbrigo, D. G. Jenkins, Iu. Skorodumina, Z. Akbar, G. Charles, A. Simonyan, F. Sabatié, N. K. Walford, S. S. Jawalkar, I. J. D. MacGregor, W. Gohn, E. Golovatch, A. Deur, L. A. Net, Latifa Elouadrhiri, C. A. Meyer, Y. G. Sharabian, G. V. Fedotov, N. Dashyan, S. E. Kuhn, Yordanka Ilieva, J. A. Fleming, Martin K. Mayer, M. Khachatryan, S. Fegan, C. Gleason, G. Ciullo, J. P. Ball, Y. Prok, D. S. Carman, Nikos Sparveris, S. Niccolai, A. Movsisyan, M. Ripani, E. Seder, Institut de Recherches sur les lois Fondamentales de l'Univers (IRFU), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay, Institut de Physique Nucléaire d'Orsay (IPNO), Université Paris-Sud - Paris 11 (UP11)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS), CLAS, and Centre National de la Recherche Scientifique (CNRS)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Université Paris-Sud - Paris 11 (UP11)
Subjects: Single spin asymmetries, Hadron, fragmentation function, 01 natural sciences, Settore FIS/04 - Fisica Nucleare e Subnucleare, transverse momentum: momentum spectrum, Collins, hadron: production, Nuclear Experiment, Spin-½, Physics, deep inelastic scattering: semi-inclusive reaction, suppression, Collins fragmentation, hadron: energy, lcsh:QC1-999, Double spin asymmetries, Semi-inclusive deep-inelastic scattering, Transverse momentum distributions, High Energy Physics - Phenomenology, transverse, electron: scattering, cryogenics, spin: asymmetry, Jefferson Lab, Nuclear and High Energy Physics, pi: momentum, Quark, Socio-culturale, quark gluon: correlation, lepton: scattering, [PHYS.NEXP]Physics [physics]/Nuclear Experiment [nucl-ex], quark, pi: electroproduction, Nuclear physics, Pion, target: spin, deep inelastic scattering, CLAS, 0103 physical sciences, 010306 general physics, 010308 nuclear & particles physics, Scattering, High Energy Physics::Phenomenology, Deep inelastic scattering, Gluon, Automatic Keywords, [PHYS.HPHE]Physics [physics]/High Energy Physics - Phenomenology [hep-ph], High Energy Physics::Experiment, higher-dimensional, lcsh:Physics, experimental results, Lepton
Abstract: We present precision measurements of the target and beam-target spin asymmetries from neutral pion electroproduction in deep-inelastic scattering (DIS) using the CEBAF Large Acceptance Spectrometer (CLAS) at Jefferson Lab. We scattered 6-GeV, longitudinally polarized electrons off longitudinally polarized protons in a cryogenic $^{14}$NH$_3$ target, and extracted double and single target spin asymmetries for $ep\rightarrow e^\prime\pi^0X$ in multidimensional bins in four-momentum transfer ($1.0, Comment: 18 preprint pages, 3 figures
Published: 2018

25. Photon beam asymmetry Σ in the reaction γ→p→pω for E= 1.152 to 1.876 GeV

Author: G. Khachatryan, W. Kim, M. Battaglieri, N. K. Walford, G. Niculescu, L. Lanza, Michael Paolone, M. Bashkanov, S. Adhikari, H. Avakian, F. X. Girod, W. J. Briscoe, Laura Clark, B. McKinnon, P. Lenisa, T. Cao, M. Ungaro, I. J. D. MacGregor, F. Sabatié, I. I. Strakovsky, H. Voskanyan, A. Kim, E. De Sanctis, V. A. Nikonov, A. Deur, E. Pasyuk, J. W. Price, N. Dashyan, C. Gleason, G. Rosner, K. Hicks, V. Mokeev, P. Nadel-Turonski, V. Batourine, I. Bedlinskiy, D. I. Sober, S. Strauch, V. Crede, William Brooks, Dustin Keller, M. Defurne, Y. Ghandilyan, D. P. Watts, Barry Ritchie, Brian Raue, Alessandro Rizzo, C. Hanretty, H. Egiyan, E. Golovatch, R. Dupre, R. A. Montgomery, A. Celentano, R. W. Gothe, M. Khachatryan, Sylvester Joosten, B. S. Ishkhanov, G. Charles, Michael Wood, J. Ball, K. Hafidi, W. Phelps, H. S. Jo, A. V. Sarantsev, G. Ciullo, Y. Prok, D. I. Glazier, D. S. Carman, A. Simonyan, O. Cortes, N. A. Baltzell, C. Munoz Camacho, Nikos Sparveris, F. J. Klein, M. Ripani, M. Contalbrigo, Z. E. Meziani, E. L. Isupov, S. Niccolai, D. G. Jenkins, M. Osipenko, K. A. Griffioen, R. Paremuzyan, Eberhard Klempt, S. Boiarinov, N. Markov, V. P. Kubarovsky, A. Movsisyan, R. De Vita, Nicholas M. Harrison, O. Pogorelko, Gerard Gilfoyle, J. Zhang, S. M. Hughes, X. Wei, S. Pisano, D. Sokhan, I. Stankovic, A. V. Anisovich, C. A. Meyer, Z. Akbar, G. V. Fedotov, I. Niculescu, C. Salgado, P. L. Cole, A. I. Ostrovidov, K. Park, R. A. Schumacher, D. G. Ireland, H. Jiang, H. Hakobyan, S. Anefalos Pereira, Volker D. Burkert, A. S. Biselli, L. El Fassi, K. P. Adhikari, S. Stepanyan, E. Munevar, L. A. Net, Avraham Klein, Y. G. Sharabian, J. A. Fleming, Iu. Skorodumina, D. Heddle, G. Hollis, P. Eugenio, M. Taiuti, P. Collins, S. Procureur, K. L. Giovanetti, A. El Alaoui, Y. Ilieva, Nicholas Zachariou, A. Filippi, M. Khandaker, K. Livingston, M. Hattawy, D. Protopopescu, Z. W. Zhao, E. Voutier, Chaden Djalali, Michael Dugger, T. Mineeva, F. Cao, D. Adikaram, M. Guidal, G. D. Smith, M. Holtrop, Taya Chetry, and Sergey Kuleshov
Subjects: Physics, Nuclear and High Energy Physics, Photon, Meson, Proton, 010308 nuclear & particles physics, Partial wave analysis, Bremsstrahlung, Photon energy, 01 natural sciences, Nuclear physics, Pomeron, 0103 physical sciences, Nuclear Experiment, 010306 general physics, Nucleon
Abstract: Photon beam asymmetry Σ measurements for ω photoproduction in the reaction γ → p → ω p are reported for photon energies from 1.152 to 1.876 GeV. Data were taken using a linearly-polarized tagged photon beam, a cryogenic hydrogen target, and the CLAS spectrometer in Hall B at Jefferson Lab. The measurements obtained markedly increase the size of the database for this observable, extend coverage to higher energies, and resolve discrepancies in previously published data. Comparisons of these new results with predictions from a chiral-quark-based model and from a dynamical coupled-channels model indicate the importance of interferences between t-channel meson exchange and s- and u-channel contributions, underscoring sensitivity to the nucleon resonances included in those descriptions. Comparisons with the Bonn–Gatchina partial-wave analysis indicate the Σ data reported here help to fix the magnitudes of the interference terms between the leading amplitudes in that calculation (Pomeron exchange and the resonant portion of the J P = 3 / 2 + partial wave), as well as the resonant portions of the smaller partial waves with J P = 1 / 2 − , 3 / 2 − , and 5 / 2 + .
Published: 2017

26. 12C(e,e'pN) measurements of short range correlations in the tensor-to-scalar interaction transition region

Author: M. J. Amaryan, P. Lenisa, Jie Zhang, A. Beck, L. Marsicano, T. B. Hayward, U. Shrestha, Larry Weinstein, S. Strauch, Maxime Defurne, K. A. Griffioen, D. P. Watts, Friedrich Klein, R. Paremuzyan, Brian Raue, O. Pogorelko, J. Rowley, A. I. Ostrovidov, R. A. Schumacher, F. X. Girod, M. Duer, A. Denniston, E. Golovatch, R. Dupre, Nicholas M. Harrison, R. De Vita, I. I. Strakovsky, P. Eugenio, A. Deur, W. K. Brooks, A. Filippi, D. Sokhan, B. A. Clary, D. Protopopescu, Volker D. Burkert, A. S. Biselli, L. Lanza, M. Khandaker, N. Tyler, C. Djalali, E. Voutier, Michael Paolone, Y. G. Sharabian, X. Zheng, H. Atac, J. A. Tan, Y. Prok, D. S. Carman, I. Bedlinskiy, W. Phelps, V. Lucherini, M. Battaglieri, A. El Alaoui, Y. Ilieva, E. L. Isupov, Nicholas Zachariou, X. Wei, S. Mey-Tal Beck, S. Boiarinov, Hovanes Egiyan, F. Hauenstein, C. Munoz Camacho, J. W. Price, Taofeng Wang, Fatiha Benmokhtar, M. Khachatryan, Nikolaos Sparveris, N. Markov, A. Movsisyan, R. Cruz-Torres, T. A. Forest, O. Soto, D. Heddle, M. Ungaro, K. P. Adhikari, Douglas Higinbotham, Latifa Elouadrhiri, D. Marchand, P. Nadel-Turonski, S. Adhikari, B. McKinnon, M. Ripani, A. Kim, S. Stepanyan, I. Korover, M. Hattawy, M. Guidal, B. Mustapha, Z. W. Zhao, T. Mineeva, Or Hen, H. Hakobyan, M. Mirazita, J. Ritman, L. Barion, J.R. Pybus, M. Holtrop, S. Diehl, R. G. Fersch, C. Salgado, K. Joo, Luciano Pappalardo, T. Chetry, E.P. Segarra, H. S. Jo, D. G. Jenkins, M. Leali, Eugene Pasyuk, P. L. Cole, M. Ehrhart, G. Rosner, P. Chatagnon, A. D'Angelo, L. El Fassi, V. P. Kubarovsky, L. Venturelli, Krishna Neupane, C. W. Kim, H. Voskanyan, W. J. Briscoe, Dustin Keller, E. Piasetzky, D. Bulumulla, Michael Wood, K. Hafidi, Aditya R. Khanal, Andrea Bianconi, G. Niculescu, Alexander Schmidt, G. Gavalian, M. Osipenko, I. J. D. MacGregor, F. Sabatié, D. G. Ireland, V. Crede, M. Contalbrigo, Laura Clark, G. Angelini, K. Hicks, A. Celentano, R. W. Gothe, Alessandro Rizzo, V. Mascagna, S. Joosten, K. Livingston, Laboratoire de Physique des 2 Infinis Irène Joliot-Curie (IJCLab), Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), and The Clas Collaboration
Subjects: Nuclear and High Energy Physics, Nuclear Theory, dependence, CLAS, dynamics, isospin, energy, system, Astronomy & Astrophysics, Physics, QC1-999, Scalar (mathematics), FOS: Physical sciences, [PHYS.NEXP]Physics [physics]/Nuclear Experiment [nucl-ex], Astrophysics, 01 natural sciences, Nuclear Theory (nucl-th), Momentum, High Energy Physics - Phenomenology (hep-ph), 0103 physical sciences, ddc:530, Tensor, Nuclear Experiment (nucl-ex), Nuclear Experiment, 010306 general physics, Nuclear theory, [PHYS]Physics [physics], Range (particle radiation), 010308 nuclear & particles physics, Settore FIS/04, Nuclear interaction, High Energy Physics - Phenomenology, Astronomy &amp, Atomic physics, Nucleon
Abstract: High-momentum configurations of nucleon pairs at short-distance are probed using measurements of the $^{12}$C$(e,e'p)$ and $^{12}$C$(e,e'pN)$ reactions (where $N$ is either $n$ or $p$), at high-$Q^2$ and $x_B>1.1$. The data span a missing-momentum range of 300--1000 MeV/c and are predominantly sensitive to the transition region of the strong nuclear interaction from a Tensor to Scalar interaction. The data are well reproduced by theoretical calculations using the Generalized Contact Formalism with both chiral and phenomenological nucleon-nucleon ($NN$) interaction models. This agreement suggests that the measured high missing-momentum protons up to $1000$ MeV/c predominantly belong to short-ranged correlated (SRC) pairs. The measured $^{12}$C$(e,e'pN)$ / $^{12}$C$(e,e'p)$ and $^{12}$C$(e,e'pp)$ / $^{12}$C$(e,e'pn)$ cross-section ratios are consistent with a decrease in the fraction of proton-neutron SRC pairs and increase in the fraction of proton-proton SRC pairs with increasing missing momentum. This confirms the transition from an isospin-dependent tensor $NN$ interaction at $\sim 400$ MeV/c to an isospin-independent scalar interaction at high-momentum around $\sim 800$ MeV/c as predicted by theoretical calculation., Accepted for publication in Physics Letters B. 7 pages, 3 figures, and online supplementary materials
Published: 2021

27. First Measurements of the Double-Polarization Observables F , P , and H in ω Photoproduction off Transversely Polarized Protons in the N* Resonance Region

Author: Eberhard Klempt, O. Cortes, C. Hanretty, K. A. Griffioen, M. Ungaro, V. A. Nikonov, X. Wei, B. S. Ishkhanov, O. Soto, C. D. Keith, S. Strauch, G. Khachatryan, F. X. Girod, M. Osipenko, A. D'Angelo, Eugene Pasyuk, H. S. Jo, A. El Alaoui, W. J. Briscoe, Y. Ilieva, Aditya R. Khanal, Dustin Keller, L. Barion, F. Sabatié, I. I. Strakovsky, L. Guo, Alessandro Rizzo, A. V. Anisovich, L. Lanza, J. Brock, V. Mokeev, E. L. Isupov, Nicholas Zachariou, K Nakayama, M. C. Kunkel, P. Nadel-Turonski, Rong Wang, R. De Vita, A. Deur, R. A. Schumacher, Michael Wood, P. Lenisa, W. Phelps, Barry Ritchie, S. Boiarinov, K. Hafidi, G. Ciullo, Y. Prok, Iu. Skorodumina, S Niccolai, P. Eugenio, W. Kim, G. Niculescu, D. S. Carman, W. K. Brooks, I. Bedlinskiy, C. A. Meyer, D. Payette, K. Livingston, Sylvester Joosten, G. Rosner, H. Egiyan, Andrea Celentano, T. B. Hayward, J. Pierce, Jie Zhang, S. Adhikari, Friedrich Klein, D. G. Jenkins, M. Taiuti, K. P. Adhikari, Brian Raue, D. P. Watts, D. Marchand, Y. G. Sharabian, A. Movsisyan, S. Diehl, M. Ripani, C. Salgado, C. Carlin, S. Fegan, M. L. Kabir, A. V. Sarantsev, M. Battaglieri, N. Tyler, B. Duran, V. P. Kubarovsky, E. Voutier, J. A. Tan, U. Shrestha, V. Crede, D. Riser, Chaden Djalali, O. Pogorelko, M. Khachatryan, Michael Dugger, T. Mineeva, H. Avakian, E. Golovatch, A Fradi, R. Dupre, H. Voskanyan, Nikolaos Sparveris, F. Cao, P. Roy, N C Wei, N. K. Walford, R. A. Montgomery, M. Guidal, E. De Sanctis, N. Dashyan, A. Kim, P. Chatagnon, I. J. D. MacGregor, Michael Paolone, M. Holtrop, M. Hattawy, R. W. Gothe, M Ehrhart, K. Hicks, Luciano Pappalardo, S. Park, Taya Chetry, M. Contalbrigo, G. Angelini, Sergey Kuleshov, D. G. Meekins, L. El Fassi, A. I. Ostrovidov, D. G. Ireland, Volker D. Burkert, A. S. Biselli, M. Khandaker, B. McKinnon, D. Heddle, P. L. Cole, M. L. Seely, B. Torayev, Feng Huang, R. Paremuzyan, Sandra K. Johnston, D. Protopopescu, Z. W. Zhao, Nicholas M. Harrison, Gerard Gilfoyle, D. Sokhan, A. Filippi, and C. Munoz Camacho
Subjects: Physics, Photon, Spectrometer, Proton, Linear polarization, media_common.quotation_subject, Nuclear Theory, General Physics and Astronomy, Resonance, Polarization (waves), 01 natural sciences, Asymmetry, Nuclear physics, 0103 physical sciences, Physics::Accelerator Physics, Nuclear Experiment, 010306 general physics, Nucleon, media_common
Abstract: First measurements of double-polarization observables in ω photoproduction off the proton are presented using transverse target polarization and data from the CEBAF Large Acceptance Spectrometer (CLAS) FROST experiment at Jefferson Lab. The beam-target asymmetry F has been measured using circularly polarized, tagged photons in the energy range 1200-2700 MeV, and the beam-target asymmetries H and P have been measured using linearly polarized, tagged photons in the energy range 1200-2000 MeV. These measurements significantly increase the database on polarization observables. The results are included in two partial-wave analyses and reveal significant contributions from several nucleon (N^{*}) resonances. In particular, contributions from new N^{*} resonances listed in the Review of Particle Properties are observed, which aid in reaching the goal of mapping out the nucleon resonance spectrum.
Published: 2019

28. First results on nucleon resonance photocouplings from the γp → π+π−p reaction

Author: I. Bedlinskiy, J. Ball, F. Cao, E. De Sanctis, M. Guidal, R. Paremuzyan, N. Markov, Y. G. Sharabian, D. I. Sober, Maxime Defurne, D. I. Glazier, I. J. D. MacGregor, R. De Vita, P. Eugenio, I. I. Strakovsky, D. Protopopescu, G. D. Smith, M. Holtrop, Z. W. Zhao, Nicholas M. Harrison, Gerard Gilfoyle, M. Taiuti, E. Voutier, A. Deur, M. Contalbrigo, M. Khachatryan, D. Sokhan, Latifa Elouadrhiri, M. L. Kabir, M. J. Amaryan, G. Ciullo, C. A. Meyer, M. Khandaker, P. Chatagnon, Y. Prok, D. S. Carman, G. V. Fedotov, Z. Akbar, F. X. Girod, Sandra K. Johnston, K. Livingston, M. Hattawy, Nikos Sparveris, K. A. Griffioen, E. Golovatch, R. Dupre, A. I. Ostrovidov, K. Park, Jie Zhang, S. Niccolai, Hovanes Egiyan, Taya Chetry, C. Munoz Camacho, A. Movsisyan, D. G. Ireland, V. Crede, F. Sabatié, Volker D. Burkert, A. S. Biselli, P. Lenisa, M. Bashkanov, S. Adhikari, B. McKinnon, K. L. Giovanetti, S. Strauch, L. Lanza, J. W. Price, V. I. Mokeev, M. Ripani, R. A. Montgomery, D. Marchand, X. Wei, D. Heddle, A. El Alaoui, Y. Ilieva, M. Battaglieri, B. A. Clary, Nicholas Zachariou, Friedrich Klein, Iu. Skorodumina, H. Hakobyan, Michael Paolone, D. G. Jenkins, N. Dashyan, S. Diehl, C. Salgado, H. S. Jo, A. Filippi, Laura Clark, L. Barion, E. L. Isupov, Michael Dugger, S. Boiarinov, R. A. Schumacher, Avraham Klein, P. Nadel-Turonski, M. Ungaro, K. Joo, N. Tyler, C. Djalali, J. A. Tan, Dustin Keller, B. S. Ishkhanov, Michael Wood, K. Hafidi, H. Avakian, H. Voskanyan, E. Pasyuk, V. P. Kubarovsky, D. Riser, O. Pogorelko, G. Khachatryan, W. J. Briscoe, G. Rosner, Y. Ghandilyan, K. Hicks, L. Guo, Alessandro Rizzo, R. G. Fersch, P. L. Cole, A. D'Angelo, L. El Fassi, M. Osipenko, Rong Wang, M. Ehrhart, W. Kim, G. Niculescu, A. Celentano, and R. W. Gothe
Subjects: Nuclear and High Energy Physics, Meson, Nuclear Theory, Hadron, Two pion photoproduction, Socio-culturale, Elementary particle, 01 natural sciences, Settore FIS/04 - Fisica Nucleare e Subnucleare, Nuclear physics, Particle decay, Pion, 0103 physical sciences, Invariant mass, Resonance photocouplings, Nuclear Experiment, 010306 general physics, Physics, 010308 nuclear & particles physics, Resonance, lcsh:QC1-999, Baryon state, High Energy Physics::Experiment, Nucleon, lcsh:Physics
Abstract: We report the first experimental measurements of the nine 1-fold differential cross sections for the γp→π+π−p reaction, obtained with the CLAS detector at Jefferson Laboratory. The measurements cover the invariant mass range of the final state hadrons from 1.6 GeV Δ(1620)1/2−, Δ(1700)3/2−, N(1720)3/2+, and Δ(1905)5/2+ resonances, which have dominant decays into the ππN final states rather than the more extensively studied single meson decay channels.
Published: 2019

29. Exploring the Structure of the Bound Proton with Deeply Virtual Compton Scattering

Author: A. El Alaoui, Alessandro Rizzo, C. Ayerbe Gayoso, M. Khandaker, R. Paremuzyan, Nicholas Zachariou, O. Soto, Andrea Celentano, Nicholas M. Harrison, Gerard Gilfoyle, D. P. Watts, S. Fegan, D. Sokhan, V. Crede, K. Livingston, M. Garçon, Sandra K. Johnston, R. A. Montgomery, Jie Zhang, F. X. Girod, M. Battaglieri, M. Contalbrigo, G. Gavalian, E. Golovatch, S. Strauch, Aditya R. Khanal, S. Niccolai, A. Filippi, M. Ripani, R. Dupre, N A Baltzell, K. L. Giovanetti, A. D'Angelo, E. L. Isupov, G. Khachatryan, Dustin Keller, Larry Weinstein, P. Lenisa, Yordanka Ilieva, M. Defurne, N. Markov, Chaden Djalali, Michael Wood, Laura Clark, E. De Sanctis, F. Sabatié, D. Heddle, K. A. Griffioen, T. Mineeva, L. Barion, K. Hafidi, J. Poudel, Taya Chetry, C. Munoz Camacho, P. L. Cole, Iu. Skorodumina, G. Angelini, P. Rossi, T. B. Hayward, D. Protopopescu, Z. W. Zhao, B. McKinnon, F. Hauenstein, Friedrich Klein, L. Lanza, B. Torayev, A Fradi, S. Diehl, C. Salgado, V. P. Kubarovsky, D. Riser, G. Ciullo, O. Pogorelko, M. Mirazita, H. Egiyan, F. Bossu, G. Rosner, P. Eugenio, Y. Prok, D. S. Carman, L. El Fassi, E. Pasyuk, M. Taiuti, C. W. Kim, Zein-Eddine Meziani, F. Cao, M. L. Kabir, S. E. Kuhn, M. Hattawy, H. Voskanyan, A. I. Ostrovidov, D. G. Jenkins, I. J. D. MacGregor, M. Guidal, Rong Wang, N. Dashyan, D. G. Ireland, M Ehrhart, A. S. Biselli, N. Gevorgyan, R. W. Gothe, M. Holtrop, I. Bedlinskiy, Luciano Pappalardo, Martin K. Mayer, A. Deur, W. Kim, M. Khachatryan, Nikolaos Sparveris, W. K. Brooks, S. Adhikari, Y. G. Sharabian, R. De Vita, D. Marchand, H. S. Jo, X. Wei, R. A. Schumacher, S. Bültmann, T. A. Forest, S. Stepanyan, Simonetta Liuti, M. Ungaro, Y. Perrin, K. Hicks, P. Chatagnon, P. Nadel-Turonski, N. Tyler, J. A. Tan, E. Voutier, Institut de Physique Nucléaire d'Orsay (IPNO), Université Paris-Sud - Paris 11 (UP11)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS), Laboratoire de Physique Subatomique et de Cosmologie (LPSC), Université Joseph Fourier - Grenoble 1 (UJF)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Institut Polytechnique de Grenoble - Grenoble Institute of Technology-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes (UGA), Institut de Recherches sur les lois Fondamentales de l'Univers (IRFU), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay, CLAS, Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes [2016-2019] (UGA [2016-2019]), Centre National de la Recherche Scientifique (CNRS)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Université Paris-Sud - Paris 11 (UP11), Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes (UGA)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP ), and Université Grenoble Alpes (UGA)
Subjects: generalized parton distribution, Proton, EMC effect, Nuclear Theory, General Physics and Astronomy, Virtual particle, parton: distribution function, Parton, Electron, 01 natural sciences, 7. Clean energy, High Energy Physics - Experiment, High Energy Physics - Experiment (hep-ex), Electromagnetic probes, [PHYS.HEXP]Physics [physics]/High Energy Physics - Experiment [hep-ex], Nuclear Experiment (nucl-ex), Form factors, Electromagnetic probes, Nuclear Structure, Deep Virtual Compton Scattering, Quark models, Electron-ion collisions, Nuclear structure & decays, Nucleon distribution, electron: beam, Nuclear Experiment, Physics, Settore FIS/04, Form factors, nucleon, matter: effect, kinematics, Quark models, Nucleon, spin: asymmetry, accelerator, FOS: Physical sciences, Socio-culturale, [PHYS.NEXP]Physics [physics]/Nuclear Experiment [nucl-ex], Nuclear Structure, Deep Virtual Compton Scattering, Nuclear physics, PE2_2, PE2_1, deeply virtual Compton scattering, CLAS, 0103 physical sciences, structure, 010306 general physics, PE2_3, Electron-ion collisions, Nuclear Physics, Scattering, Nuclear structure &amp, Compton scattering, Automatic Keywords, Physics::Accelerator Physics, High Energy Physics::Experiment, Nucleon distribution, spectrometer, decays, experimental results, photon: virtual
Abstract: In the past two decades, deeply virtual Compton scattering of electrons has been successfully used to advance our knowledge of the partonic structure of the free proton and investigate correlations between the transverse position and the longitudinal momentum of quarks inside the nucleon. Meanwhile, the structure of bound nucleons in nuclei has been studied in inclusive deep-inelastic lepton scattering experiments off nuclear targets, showing a significant difference in longitudinal momentum distribution of quarks inside the bound nucleon, known as the EMC effect. In this work, we report the first beam spin asymmetry (BSA) measurement of exclusive deeply virtual Compton scattering (DVCS) off a proton bound in $^4$He. The data used here were accumulated using a $6$ GeV longitudinally polarized electron beam incident on a pressurized $^4$He gaseous target placed within the CLAS spectrometer in Hall-B at the Thomas Jefferson National Accelerator Facility. The azimuthal angle ($\phi$) dependence of the BSA was studied in a wide range of virtual photon and scattered proton kinematics. The $Q^2$, $x_B$, and t dependencies of the BSA on the bound proton are compared with those on the free proton. In the whole kinematical region of our measurements, the BSA on the bound proton is smaller by 20\% to 40\%, indicating possible medium modification of its partonic structure.
Published: 2019

30. Direct Observation of Proton-Neutron Short-Range Correlation Dominance in Heavy Nuclei

Author: W. Phelps, T. B. Hayward, Or Hen, Rong Wang, Friedrich Klein, P. Eugenio, M. Taiuti, M. L. Kabir, Andrea Celentano, X. Wei, J.R. Pybus, L. Guo, A. Beck, S. Niccolai, Laura Clark, A. I. Ostrovidov, G. Rosner, M. Contalbrigo, A. Denniston, D. G. Ireland, C. Hanretty, A. Hrnjic, G. Niculescu, K. A. Griffioen, G. Ciullo, G. Angelini, P. Rossi, D. S. Carman, Volker D. Burkert, A. S. Biselli, R. Cruz Torres, K. Livingston, A. Rizzo, M. Duer, Michael Paolone, N. Markov, H. S. Jo, Iu. Skorodumina, A. Movsisyan, S. Diehl, Y. Prok, E. L. Isupov, B. McKinnon, N. Tyler, M. Osipenko, R. W. Gothe, M. Khandaker, Michael Wood, J. A. Tan, V. Crede, Y. Ilieva, K. Joo, E. De Sanctis, F. Cao, B. Duran, I. Korover, R. A. Montgomery, K. Hicks, D. Heddle, I. Bedlinskiy, S. Stepanyan, H. Voskanyan, F. Hauenstein, R. A. Schumacher, M. Battaglieri, Chaden Djalali, F. X. Girod, B. Mustapha, E. Pasyuk, N. Dashyan, H. Hakobyan, A. D'Angelo, F. Sabatié, M. Holtrop, M. Mirazita, I. J. D. MacGregor, Eliahu Cohen, K. Park, A. El Alaoui, P. Nadel-Turonski, H. Egiyan, T. A. Forest, W. Kim, B. S. Ishkhanov, David M. Keller, E.P. Segarra, L. El Fassi, Aditya R. Khanal, Nicholas Zachariou, S. E. Kuhn, Eli Piasetzky, M. Ripani, S. Strauch, V. P. Kubarovsky, Taya Chetry, M. Hattawy, Nir Barnea, Axel Schmidt, J. Zhang, D. Protopopescu, P. L. Cole, Z. W. Zhao, E. Voutier, Y. G. Sharabian, A. Deur, W. K. Brooks, S. Adhikari, E. Golovatch, R. Dupre, Ronen Weiss, K. Hafidi, L. Lanza, M. Khachatryan, C. Munoz Camacho, Nikolaos Sparveris, M. Patsyuk, R. Paremuzyan, Nicholas M. Harrison, Gerard Gilfoyle, D. Sokhan, A. Filippi, K. L. Giovanetti, Larry Weinstein, X. Zheng, R. De Vita, S. Mey-Tal Beck, B. Schmookler, D. Marchand, M. Ungaro, G. Laskaris, S. Boiarinov, O. Pogorelko, O. Cortes, Victor Mokeev, P. Lenisa, Institut de Physique Nucléaire d'Orsay (IPNO), Centre National de la Recherche Scientifique (CNRS)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Université Paris-Sud - Paris 11 (UP11), Institut de Recherches sur les lois Fondamentales de l'Univers (IRFU), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay, CLAS, and Université Paris-Sud - Paris 11 (UP11)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS)
Subjects: Triple coincidence, Nuclear Theory, [PHYS.NUCL]Physics [physics]/Nuclear Theory [nucl-th], General Physics and Astronomy, Socio-culturale, FOS: Physical sciences, [PHYS.NEXP]Physics [physics]/Nuclear Experiment [nucl-ex], 01 natural sciences, Nuclear matter in neutron stars, Correlation, Nuclear Theory (nucl-th), 0103 physical sciences, Neutron, Nuclear Experiment (nucl-ex), 010306 general physics, Nuclear Experiment, Nuclear theory, Asymmetric nuclear matter,Lepton induced nuclear reactions, Nuclear matter in neutron stars, Nucleon distribution, Nucleon-nucleon interactions, Nuclear Physics, Physics, Settore FIS/04, Direct observation, Formalism (philosophy of mathematics), Lepton induced nuclear reactions, Nucleon-nucleon interactions, Nucleon distribution, Atomic physics, Nucleon, Asymmetric nuclear matter
Abstract: We measured the triple coincidence A(e,e'np) and A(e,e'pp) reactions on carbon, aluminum, iron, and lead targets at Q2 > 1.5 (GeV/c)2, xB > 1.1 and missing momentum > 400 MeV/c. This was the first direct measurement of both proton-proton (pp) and neutron-proton (np) short-range correlated (SRC) pair knockout from heavy asymmetric nuclei. For all measured nuclei, the average proton-proton (pp) to neutron-proton (np) reduced cross-section ratio is about 6%, in agreement with previous indirect measurements. Correcting for Single-Charge Exchange effects decreased the SRC pairs ratio to ~ 3%, which is lower than previous results. Comparisons to theoretical Generalized Contact Formalism (GCF) cross-section calculations show good agreement using both phenomenological and chiral nucleon-nucleon potentials, favoring a lower pp to np pair ratio. The ability of the GCF calculation to describe the experimental data using either phenomenological or chiral potentials suggests possible reduction of scale- and scheme-dependence in cross section ratios. Our results also support the high-resolution description of high-momentum states being predominantly due to nucleons in SRC pairs., Accepted for publication in PRL. 9 pages, 3 figures, 3 tables and supplementary materials
Published: 2019

31. Ξ* photoproduction from threshold to W=3.3GeV

Author: Frank Klein, Dustin Keller, K. Hafidi, E. Golovatch, Y. G. Sharabian, K. Hicks, M. Ripani, C. Bookwalter, K. A. Griffioen, L. Lanza, H. Egiyan, V. Crede, I. J. D. MacGregor, M. Contalbrigo, S. Adhikari, M. Hattawy, C. Munoz Camacho, M. H. Wood, B. McKinnon, I. Bedlinskiy, D. Protopopescu, Michael Dugger, M. Osipenko, L. Elouadrhiri, M. Khachatryan, M. S. Saini, G. Ciullo, P. Eugenio, M. Taiuti, A. El Alaoui, Carlos A. Salgado, F. Cao, W. Kim, I. I. Strakovsky, Maxime Defurne, A. Deur, J. T. Goetz, Y. Prok, D. S. Carman, M. Mirazita, Nikos Sparveris, B. S. Ishkhanov, Nicholas Zachariou, M. L. Kabir, Diane Schott, Michael Paolone, C. A. Meyer, A. I. Ostrovidov, K. Park, X. Wei, N. Gevorgyan, D. I. Glazier, P. Chatagnon, G. V. Fedotov, D. G. Ireland, R. De Vita, M. Guidal, E. Voutier, A. Movsisyan, J. Zhang, F. Sabatié, G. Niculescu, S. Chandavar, V. P. Kubarovsky, Volker D. Burkert, A. S. Biselli, K. Livingston, J. W. Price, A. Celentano, R. W. Gothe, S. Anefalos Pereira, R. Paremuzyan, D. Riser, V. Mokeev, D. P. Weygand, A. Filippi, M. C. Kunkel, Brian Raue, O. Pogorelko, Nicholas M. Harrison, Rong Wang, M. Holtrop, S. Niccolai, R. Dupre, M. Battaglieri, M. Khandaker, Alessandro Rizzo, D. Sokhan, D. I. Sober, L. Guo, M. Ehrhart, M. Ungaro, Pawel Nadel-Turonski, H. Voskanyan, W. J. Briscoe, E. Pasyuk, Iu. Skorodumina, D. Heddle, Taya Chetry, William Brooks, P. L. Cole, Z. W. Zhao, R. A. Schumacher, A. D'Angelo, F. X. Girod, L. El Fassi, S. Strauch, E. L. Isupov, S. Boiarinov, H. Hakobyan, H. S. Jo, S. Diehl, Sylvester Joosten, C. Djalali, J. A. Tan, G. Khachatryan, N. Dashyan, A. Kim, G. Rosner, and Y. Ghandilyan
Subjects: Quark, Physics, Particle physics, 010308 nuclear & particles physics, Nuclear Theory, Quark model, Lattice field theory, 01 natural sciences, Xi baryon, Baryon, Lattice (order), Excited state, 0103 physical sciences, High Energy Physics::Experiment, Gauge theory, Nuclear Experiment, 010306 general physics
Abstract: The doubly strange Xi baryons provide an effective way to study a puzzle called the missing-baryons problem where both quark models and lattice guage theory predict more baryon excited states than are seen experimentally. However, few of these excited states have been observed with any certainty. Here, high-mass Xi* states have been searched for in photoproduction with the detector of the CLAS collaboration, and upper limits for the total cross sections have been established from threshold to W = 3.3 GeV. In addition, the total cross sections of the ground-state Xi(-)(1320) and first excited state Xi(-)(1530) are presented, extending significantly the centre-of-mass energy range of previous data.
Published: 2018

32. Beam-target helicity asymmetry E in K0Λ and K0Σ0 photoproduction on the neutron

Author: P. Lenisa, M. Ungaro, D. G. Ireland, C. A. Meyer, R. Dupre, V. Crede, C.D. Bass, V. A. Nikonov, M. Battaglieri, P. Chatagnon, G. V. Fedotov, R. A. Montgomery, Ron L. Workman, R. Paremuzyan, R. A. Schumacher, C. S. Whisnant, K. P. Adhikari, A. Fradi, M. Osipenko, D. G. Jenkins, Nicholas M. Harrison, N. Markov, Martin K. Mayer, K. A. Griffioen, I. Zonta, I. J. D. MacGregor, A. Kim, H. Hakobyan, M. Khachatryan, D. Sokhan, H. S. Jo, Tim O'Connell, D. Marchand, S. Diehl, M. Bashkanov, B. McKinnon, A. I. Ostrovidov, K. Park, V. Mokeev, G. Khachatryan, L. Lanza, Eberhard Klempt, P. Collins, S. Niccolai, F. X. Girod, M. Contalbrigo, Sandra K. Johnston, P. Eugenio, T. Chetry, Volker D. Burkert, A. S. Biselli, Pawel Nadel-Turonski, M. Mirazita, J. Zhang, Rong Wang, J. W. Price, Alessandro Rizzo, S. Strauch, Iu. Skorodumina, C. Hanretty, George Davey Smith, M. Taiuti, C. Djalali, J. A. Tan, E. Golovatch, Y. G. Sharabian, M. Lowry, G. Charles, K. L. Giovanetti, I. Bedlinskiy, M. Rehfuss, K. Hicks, S. Adhikari, M. L. Kabir, M. Ehrhart, F. Sabatié, Andreas Klein, V. Laine, F. Cao, D. Adikaram, M. Guidal, W. Kim, Larry Weinstein, Z. Akbar, G. Rosner, P. Peng, C. Munoz Camacho, M. H. Wood, M. Hattawy, G. Niculescu, J. A. Fleming, I. I. Strakovsky, M. Holtrop, A. Filippi, A. D'Angelo, M. Ripani, Y. Ghandilyan, Carlos A. Salgado, B. A. Clary, A. M. Sandorfi, B. S. Ishkhanov, M. Khandaker, D. I. Sober, A. Deur, Hong Lu, Michael Paolone, D. Ho, S. Fegan, A. Celentano, R. W. Gothe, D. Heddle, Maxime Defurne, E. L. Isupov, W. Gohn, S. Boiarinov, R. De Vita, T. Kageya, L. El Fassi, N. K. Walford, R. G. Fersch, Frank Klein, P. L. Cole, Z. W. Zhao, Dustin Keller, G. Ciullo, J. P. Ball, Y. Prok, D. S. Carman, Nikos Sparveris, X. Wei, K. Hafidi, E. Voutier, A. Movsisyan, Yordanka Ilieva, L. Barion, V. P. Kubarovsky, D. Riser, A. El Alaoui, Nicholas Zachariou, O. Pogorelko, K. Livingston, H. Voskanyan, D. Protopopescu, W. J. Briscoe, E. Pasyuk, D. P. Watts, H. Egiyan, A. V. Sarantsev, and S. Chandavar
Subjects: Physics, Strange quark, 010308 nuclear & particles physics, media_common.quotation_subject, Nuclear Theory, Quark model, Hyperon, 01 natural sciences, Helicity, Asymmetry, Pseudoscalar meson, Nuclear physics, 13. Climate action, Isospin, 0103 physical sciences, Neutron, Nuclear Experiment, 010306 general physics, media_common
Abstract: We report the first measurements of the E beam-target helicity asymmetry for the γn→K0Λ and K0Σ0 channels in the energy range 1.70≤W≤2.34 GeV. The CLAS system at Jefferson Lab uses a circularly polarized photon beam and a target consisting of longitudinally polarized solid molecular hydrogen deuteride with low background contamination for the measurements. The multivariate analysis method boosted decision trees is used to isolate the reactions of interest. Comparisons with predictions from the KaonMAID, SAID, and Bonn-Gatchina models are presented. These results will help separate the isospin I=0 and I=1 photocoupling transition amplitudes in pseudoscalar meson photoproduction.
Published: 2018

33. First measurement of the polarization observable E in the p→(γ→,π+)n reaction up to 2.25 GeV

Author: I. Zonta, William Brooks, X. Wei, P. Lenisa, K. Livingston, D. P. Watts, Friedrich Klein, A. V. Sarantsev, D. Rönchen, P. Nadel-Turonski, Z. W. Zhao, Eberhard Klempt, W. Gohn, F. Sabatié, R. A. Badui, H. Y. Lu, I. Niculescu, I. I. Strakovsky, B. A. Raue, R. A. Schumacher, A. El Alaoui, Barry Ritchie, J. W. Price, A. Deur, Nicholas Zachariou, K. A. Griffioen, S. Chandavar, A. V. Anisovich, L. Guo, M. Ungaro, M. Ripani, R. W. Gothe, Michael Döring, T. A. Forest, S. Stepanyan, E. Munevar, Avraham Klein, Iu. Skorodumina, P. Eugenio, C. I. Moody, M. Taiuti, V. Crede, V. A. Nikonov, Latifa Elouadrhiri, G. Khachatryan, C. A. Meyer, G.V. O'Rielly, A. Trivedi, K. Joo, G. V. Fedotov, Andrea Celentano, Andrew Puckett, R. A. Montgomery, A. Kim, E. Golovatch, R. Dupre, S. Procureur, D. Keller, R. De Vita, D. Protopopescu, M. Contalbrigo, D. G. Jenkins, S. Pozdniakov, I. Bedlinskiy, K. P. Adhikari, N. Benmouna, F. X. Girod, J. Brock, H. S. Jo, N. Compton, Jian Zhang, C. Carlin, A. Filippi, Nikolaos Sparveris, N. Gevorgyan, W. Kim, S. Strauch, D. S. Carman, Victor Mokeev, G. Niculescu, D. Ho, K. Park, L. Colaneri, M. Khandaker, John Phillips, A. Simonyan, E. Seder, N. Markov, S. Pisano, N. K. Walford, M. Hattawy, D. I. Glazier, E. Voutier, T. Cao, A. Fradi, O. Pogorelko, D. G. Meekins, Diane Schott, G. Rosner, I. J. D. MacGregor, A. I. Ostrovidov, M. Osipenko, D. G. Ireland, H. Moutarde, M. Battaglieri, Y. Ghandilyan, H. Jiang, B. S. Ishkhanov, Volker D. Burkert, S. E. Kuhn, A. S. Biselli, K. L. Giovanetti, J. A. Fleming, L. El Fassi, P. Peng, Hovanes Egiyan, Chaden Djalali, Michael Dugger, Hrachya Hakobyan, Y. Ilieva, C. Munoz Camacho, R. Tucker, Ron L. Workman, P. L. Cole, B. McKinnon, L. A. Net, S. Fegan, Eugene Pasyuk, S. Anefalos Pereira, Y. G. Sharabian, W. Phelps, V. Batourine, M. L. Seely, D. Sokhan, E. De Sanctis, C. D. Keith, J. P. Ball, Y. Prok, D. I. Sober, A. Rizzo, S. Niccolai, C. Hanretty, V. Sytnik, N. Harrison, A. Movsisyan, N. Dashyan, P. Stoler, I. Senderovich, K. Hicks, G. Charles, P. Roy, D. Adikaram, M. Guidal, S. Joosten, G. D. Smith, M. Holtrop, H. Voskanyan, W. J. Briscoe, V. P. Kubarovsky, Annalisa D'Angelo, S. M. Hughes, Michael Wood, K. Hafidi, O. Cortes, E. L. Isupov, Ye Tian, Lorenzo Zana, and C. Salgado
Subjects: Physics, Nuclear physics, Nuclear and High Energy Physics, Particle physics, Photon, Pion, Meson, Bremsstrahlung, Observable, Photon energy, Nuclear Experiment, Multipole expansion, Nucleon
Abstract: First results from the longitudinally polarized frozen-spin target (FROST) program are reported. The double-polarization observable E, for the reaction (p) over right arrow((gamma) over right arrow, pi(+))n, has been measured using a circularly polarized tagged-photon beam, with energies from 0.35 to 2.37 GeV. The final-state pions were detected with the CEBAF Large Acceptance Spectrometer in Hall B at the Thomas Jefferson National Accelerator Facility. These polarization data agree fairly well with previous partial-wave analyses at low photon energies. Over much of the covered energy range, however, significant deviations are observed, particularly in the high-energy region where high-L multipoles contribute. The data have been included in new multipole analyses resulting in updated nucleon resonance parameters. We report updated fits from the Bonn-Gatchina, Jfilich-Bonn, and SAID groups. (C) 2015 The Authors. Published by Elsevier B.V.
Published: 2015

34. Photoproduction of K+K− meson pairs on the proton

Author: G. Ricco, R. A. Schumacher, K. Mikhailov, L. Bibrzycki, P. Stoler, A. D'Angelo, K. Hicks, H. Hakobyan, Ashot Gasparian, L. Gan, V. Mokeev, A.V. Stavinsky, K. Livingston, D. S. Dale, S. Anefalos Pereira, A. V. Vlassov, D. J. Tedeschi, V. V. Mochalov, K. A. Griffioen, S. Fegan, E. Clinton, Michael Wood, N. Hassall, M. Bellis, K. Hafidi, Michael Vineyard, R. De Vita, S. Stepanyan, C. Bookwalter, P. Nadel-Turonski, M. Kossov, Avraham Klein, T. Mineeva, V. Drozdov, S. Strauch, V. Kuznetsov, Friedrich Klein, D. P. Watts, E. L. Isupov, E. Munevar, H. Egiyan, I. Nakagawa, I. Bedlinskiy, Brian Raue, W. J. Briscoe, Michael L. Williams, A. Kubarovsky, W. Gohn, E. Wolin, Lorenzo Zana, M. Y. Gabrielyan, C. E. Hyde, O. Glamazdin, M. R. Niroula, Z. W. Zhao, S. Niccolai, Y. Prok, D. S. Carman, M. Battaglieri, Barry Ritchie, N. Pivnyuk, I. I. Strakovsky, D. Protopopescu, C. Salgado, E. De Sanctis, M. Garçon, S. Pozdniakov, A. Deur, G. E. Dodge, Martin K. Mayer, G. Rosner, H. Y. Lu, Kei Moriya, C. A. Meyer, M. Osipenko, N. Dashyan, D. I. Sober, F. X. Girod, E. Pasyuk, G. V. Fedotov, S. Tkachenko, Adam P. Szczepaniak, M. S. Saini, I. Niculescu, P. Eugenio, H. Baghdasaryan, K. P. Adhikari, D. P. Weygand, E. Golovatch, M. Taiuti, J. T. Goetz, D. Schott, J. W. Price, C. Djalali, F. Sabatié, V. P. Kubarovsky, O. Pogorelko, W. Kim, P. Collins, M. Anghinolfi, Leonard Lesniak, H. Seraydaryan, J. Zhang, P. Khetarpal, Y. G. Sharabian, C. S. Nepali, M. Ripani, V. Crede, C. Hanretty, J. R. Johnstone, L. Guo, M. Ungaro, S. Park, P. Rossi, K. Joo, M. Guidal, M. Holtrop, A. Daniel, A. I. Ostrovidov, K. Park, Sergey Kuleshov, D. G. Ireland, S. S. Stepanyan, Mark W. Paris, B. Zhao, Volker D. Burkert, A. S. Biselli, S. Dhamija, R. W. Gothe, A. Fradi, M. J. Amaryan, J. Goett, B. McKinnon, D. Branford, S. Pisano, M. Mirazita, S. L. Careccia, J. M. Laget, K. L. Giovanetti, Larry Weinstein, D. Keller, Gerard Gilfoyle, M. Khandaker, M. E. McCracken, Y. Ilieva, D. Sokhan, D. Doughty, A. Teymurazyan, and P. L. Cole
Subjects: Physics, Particle physics, Meson, 010308 nuclear & particles physics, Partial wave analysis, Hadron, Elementary particle, 01 natural sciences, 7. Clean energy, Particle decay, Pion, 0103 physical sciences, High Energy Physics::Experiment, Production (computer science), Nuclear Experiment, 010306 general physics, Nucleon
Abstract: The exclusive reaction $\ensuremath{\gamma}p\ensuremath{\rightarrow}p{\ensuremath{\pi}}^{+}{\ensuremath{\pi}}^{\ensuremath{-}}$ was studied in the photon energy range 3.0--3.8 GeV and the momentum transfer range $0.4l\ensuremath{-}tl1.0\text{ }\text{ }{\mathrm{GeV}}^{2}$. Data were collected with the CLAS detector at the Thomas Jefferson National Accelerator Facility. In this kinematic range, the integrated luminosity was about $20\text{ }\text{ }{\mathrm{pb}}^{\ensuremath{-}1}$. The reaction was isolated by detecting the ${\ensuremath{\pi}}^{+}$ and proton in CLAS, and reconstructing the ${\ensuremath{\pi}}^{\ensuremath{-}}$ via the missing-mass technique. Moments of the di-pion decay angular distributions were derived from the experimental data. Differential cross sections for the $S$, $P$, and $D$-waves, in the ${M}_{{\ensuremath{\pi}}^{+}{\ensuremath{\pi}}^{\ensuremath{-}}}$ mass range 0.4--1.4 GeV, were derived performing a partial wave expansion of the extracted moments. Beside the dominant contribution of the $\ensuremath{\rho}(770)$ meson in the $P$-wave, evidence for the ${f}_{0}(980)$ and the ${f}_{2}(1270)$ mesons was found in the $S$ and $D$-waves, respectively. The differential production cross sections $d\ensuremath{\sigma}/dt$ for individual waves in the mass range of the above-mentioned mesons were extracted. This is the first time the ${f}_{0}(980)$ has been measured in a photoproduction experiment.
Published: 2018

35. Center of Mass Motion of Short-Range Correlated Nucleon Pairs studied via the A(e,e′pp) Reaction

Author: D. Protopopescu, Z. W. Zhao, E. Voutier, M. Duer, D. Marchand, X. Wei, Dustin Keller, P. Eugenio, I. J. D. MacGregor, G. Ciullo, M. Taiuti, C. Djalali, J. A. Tan, W. Kim, Y. Prok, F. Sabatié, L. Lanza, J. P. Ball, D. S. Carman, G. Niculescu, M. L. Kabir, P. Lenisa, S. Strauch, Michael Wood, K. Hafidi, B. A. Clary, K. Livingston, D. G. Jenkins, S. Niccolai, A. Movsisyan, Jie Zhang, Michael Paolone, D. Heddle, A. Celentano, R. W. Gothe, N. Dashyan, Maxime Defurne, H. Avakian, S. E. Kuhn, Friedrich Klein, M. Contalbrigo, A. Beck, Hovanes Egiyan, C. Munoz Camacho, M. Osipenko, M. Ungaro, Eli Piasetzky, H. Voskanyan, R. Fersch, Or Hen, Z. Akbar, L. Barion, R. De Vita, P. Nadel-Turonski, V. Crede, Alessandro Rizzo, Eliahu Cohen, E. Golovatch, R. Dupre, W. J. Briscoe, E. Pasyuk, A. El Alaoui, R. A. Montgomery, R. Paremuzyan, V. Mokeev, M. Battaglieri, M. Ripani, F. Hauenstein, B. S. Ishkhanov, Nicholas M. Harrison, Nicholas Zachariou, Rong Wang, D. Sokhan, Alexander Schmidt, D. P. Watts, S. Adhikari, K. Hicks, B. McKinnon, E. De Sanctis, S. Mey-Tal Beck, A. Kim, V. P. Kubarovsky, Y. G. Sharabian, D. Riser, A. I. Ostrovidov, A. Filippi, P. Rossi, X. Zheng, M. Ehrhart, O. Pogorelko, M. Mirazita, A. Deur, D. G. Ireland, I. Bedlinskiy, M. Khachatryan, M. Khandaker, Nikolaos Sparveris, Volker D. Burkert, A. S. Biselli, M. J. Amaryan, Sandra K. Johnston, K. L. Giovanetti, Larry Weinstein, B. Schmookler, C. A. Meyer, P. Chatagnon, G. V. Fedotov, F. Cao, I. Korover, B. Mustapha, M. Holtrop, Taya Chetry, G. Charles, E. L. Isupov, S. Boiarinov, R. Cruz Torres, H. Hakobyan, S. Diehl, F. X. Girod, J. W. Price, R. A. Schumacher, S. Stepanyan, Avraham Klein, H. S. Jo, A. D'Angelo, L. El Fassi, G. Khachatryan, G. Rosner, Y. Ghandilyan, and K. A. Griffioen
Subjects: Physics, Range (particle radiation), 010308 nuclear & particles physics, Nuclear Theory, General Physics and Astronomy, 01 natural sciences, 7. Clean energy, Momentum, medicine.anatomical_structure, Quantum state, 0103 physical sciences, medicine, Nuclear force, Center of mass, Atomic physics, Nuclear Experiment, 010306 general physics, Nucleon, Nucleus, Fermi Gamma-ray Space Telescope
Abstract: Short-range correlated (SRC) nucleon pairs are a vital part of the nucleus, accounting for almost all nucleons with momentum greater than the Fermi momentum (k_{F}). A fundamental characteristic of SRC pairs is having large relative momenta as compared to k_{F}, and smaller center of mass (c.m.) which indicates a small separation distance between the nucleons in the pair. Determining the c.m. momentum distribution of SRC pairs is essential for understanding their formation process. We report here on the extraction of the c.m. motion of proton-proton (pp) SRC pairs in carbon and, for the first time in heavier and ansymetric nuclei: aluminum, iron, and lead, from measurements of the A(e,e^{'}pp) reaction. We find that the pair c.m. motion for these nuclei can be described by a three-dimensional Gaussian with a narrow width ranging from 140 to 170 MeV/c, approximately consistent with the sum of two mean-field nucleon momenta. Comparison with calculations appears to show that the SRC pairs are formed from mean-field nucleons in specific quantum states.
Published: 2018

36. Measurements of the γvp→p′π+π− cross section with the CLAS detector for 0.4GeV2<Q2<1.0GeV2 and 1.3GeV<W<1.825GeV

Author: Z. W. Zhao, S. Strauch, Whitney Armstrong, M. Battaglieri, K. Park, Volker D. Burkert, H. Hakobyan, R. A. Schumacher, A. S. Biselli, P. Eugenio, T. Mineeva, Barry Ritchie, M. Khandaker, Y. Ilieva, M. Khachatryan, S. Johnston, N. Markov, M. Hattawy, I. Bedlinskiy, Nicholas Zachariou, M. L. Kabir, Maxime Defurne, F. X. Girod, G. Khachatryan, G. Charles, D. G. Ireland, P. Nadel-Turonski, B. A. Clary, Y. Prok, F. Sabatié, X. Wei, R. De Vita, K. Hicks, Michael Paolone, S. Procureur, M. Ungaro, R. A. Montgomery, Sylvester Joosten, M. Osipenko, K. Livingston, J. W. Price, G. Ciullo, J. P. Ball, D. S. Carman, D. Heddle, K. A. Griffioen, I. I. Strakovsky, G. D. Smith, M. Holtrop, S. Niccolai, I. J. D. MacGregor, Jie Zhang, Avraham Klein, Nikos Sparveris, A. Deur, Hovanes Egiyan, C. Munoz Camacho, A. D'Angelo, V. Mokeev, E. De Sanctis, Y. Ghandilyan, N. Dashyan, G. V. Fedotov, A. Celentano, R. W. Gothe, R. Paremuzyan, Taya Chetry, L. Lanza, P. Lenisa, W. K. Brooks, Nicholas M. Harrison, Gerard Gilfoyle, D. I. Sober, M. Ripani, A. Kim, D. Sokhan, G. Gavalian, Y. G. Sharabian, D. G. Jenkins, M. Bashkanov, S. Adhikari, Iu. Skorodumina, B. McKinnon, L. Guo, Sergey Kuleshov, W. Kim, G. Niculescu, E. Golovatch, R. Dupre, L. El Fassi, Alessandro Rizzo, V. Batourine, L. Barion, Friedrich Klein, M. Contalbrigo, N. Tyler, C. Djalali, J. A. Tan, C. Hanretty, H. S. Jo, B. S. Ishkhanov, M. Taiuti, R. G. Fersch, P. L. Cole, C. Salgado, O. Cortes, E. L. Isupov, S. Boiarinov, D. Protopopescu, E. Voutier, I. Balossino, Dustin Keller, Michael Wood, K. Hafidi, H. Avakian, H. Voskanyan, W. J. Briscoe, E. Pasyuk, V. P. Kubarovsky, D. Riser, and O. Pogorelko
Subjects: Physics, Photon, 010308 nuclear & particles physics, Detector, 01 natural sciences, Nuclear physics, Cross section (physics), Reaction model, 0103 physical sciences, High Energy Physics::Experiment, Invariant mass, Nuclear Experiment, 010306 general physics, Nucleon
Abstract: New results on the single-differential and fully integrated cross sections for the process γvp→p′π+π- are presented. The experimental data were collected with the CLAS detector at Jefferson Laboratory. Measurements were carried out in the kinematic region of the reaction invariant mass W from 1.3 to 1.825 GeV and the photon virtuality Q2 from 0.4 to 1.0 GeV2. The cross sections were obtained in narrow Q2 bins (0.05 GeV2) with the smallest statistical uncertainties achieved in double-pion electroproduction experiments to date. The results were found to be in agreement with previously available data where they overlap. A preliminary interpretation of the extracted cross sections, which was based on a phenomenological meson-baryon reaction model, revealed substantial relative contributions from nucleon resonances. The data offer promising prospects to improve knowledge on the Q2 evolution of the electrocouplings of most resonances with masses up to ∼1.8 GeV.
Published: 2018

37. Exclusive photoproduction of π0 up to large values of Mandelstam variables s,t, and u with CLAS

Author: S. Adhikari, S. E. Kuhn, M. Hattawy, P. Eugenio, Taya Chetry, E. Golovatch, M. Taiuti, D. Lersch, M. L. Kabir, E. De Sanctis, Carlos A. Salgado, Michael Paolone, S. Procureur, D. I. Sober, D. Protopopescu, G. V. Fedotov, A. Roy, M. Ripani, M. Khachatryan, D. P. Weygand, R. Dupre, M. Battaglieri, Maxime Defurne, M. C. Kunkel, J. Ritman, F. Cao, M. Guidal, Michael Dugger, G. Gavalian, V. P. Kubarovsky, O. Pogorelko, D. I. Glazier, G. Niculescu, P. Lenisa, A. El Alaoui, Barry Ritchie, Iu. Skorodumina, I. Balossino, D. G. Ireland, V. Crede, Frank Klein, I. Bedlinskiy, K. A. Griffioen, R. De Vita, W. Gohn, V. Mokeev, M. Holtrop, L. Elouadrhiri, Y. G. Sharabian, Andreas Klein, Nicholas Zachariou, G. Mbianda Njencheu, W. Phelps, R. A. Schumacher, Dustin Keller, I. I. Strakovsky, A. Filippi, A. Deur, C. Djalali, R. A. Montgomery, K. Hafidi, V. Batourine, H. Avakian, J. A. Tan, L. Lanza, A. D'Angelo, D. P. Watts, D. G. Jenkins, H. Voskanyan, K. Livingston, F. Sabatié, H. Egiyan, M. Khandaker, S. Niccolai, J. Zhang, S. Bültmann, W. J. Briscoe, E. Pasyuk, Alessandro Rizzo, L. El Fassi, J. W. Price, C. E. Hyde, F. X. Girod, L. Guo, M. Ungaro, T. Mineeva, R. G. Fersch, Pawel Nadel-Turonski, P. L. Cole, Z. W. Zhao, K. Hicks, Laura Clark, W. Kim, K. Joo, S. Strauch, G. Charles, B. S. Ishkhanov, O. Cortes, G. Ciullo, E. L. Isupov, J. P. Ball, Y. Prok, D. S. Carman, D. Payette, M. Osipenko, S. Boiarinov, Nikos Sparveris, X. Wei, I. J. D. MacGregor, K. P. Adhikari, A. Kim, E. Voutier, A. Movsisyan, N. Dashyan, H. Hakobyan, S. Stepanyan, L. Barion, M. J. Amaryan, K. L. Giovanetti, Larry Weinstein, G. Khachatryan, S. Schadmand, William Brooks, G. Rosner, S. Ghosh, Y. Ghandilyan, P. V. Degtyarenko, A. Celentano, R. W. Gothe, M. Contalbrigo, C. Munoz Camacho, J. Poudel, B. McKinnon, J. M. Laget, Nicholas M. Harrison, Gerard Gilfoyle, D. Sokhan, A. Fradi, N. Markov, A. I. Ostrovidov, K. Park, G. R. Goldstein, Volker D. Burkert, and A. S. Biselli
Subjects: Quark, Quantum chromodynamics, Physics, Meson, 010308 nuclear & particles physics, Perturbative QCD, Parton, Mandelstam variables, Photon energy, 01 natural sciences, Nuclear physics, 0103 physical sciences, High Energy Physics::Experiment, Sum rule in quantum mechanics, 010306 general physics
Abstract: Exclusive photoproduction cross sections have been measured for the process γ p → p π 0 [ e + e − ( γ ) ] with the Dalitz decay final state using tagged photon energies in the range of E γ = 1.275 – 5.425 GeV. The complete angular distribution of the final state π 0 , for the entire photon energy range up to large values of t and u , has been measured for the first time. The data obtained show that the cross section d σ / d t , at mid to large angles, decreases with energy as s − 6.89 ± 0.26 . This is in agreement with the perturbative QCD quark counting rule prediction of s − 7 . Paradoxically, the size of angular distribution of measured cross sections is greatly underestimated by the QCD-based generalized parton distribution mechanism at highest available invariant energy s = 11 GeV 2 . At the same time, the Regge-exchange-based models for π 0 photoproduction are more consistent with experimental data.
Published: 2018

38. Differential cross section for γd → ωd using CLAS at Jefferson Lab

Author: R. W. Gothe, I. J. D. MacGregor, M. Contalbrigo, K. A. Griffioen, S. Adhikari, S. Strauch, V. Crede, Taya Chetry, A. Filippi, I. I. Strakovsky, A. Deur, G. Ciullo, J. P. Ball, Y. Prok, D. S. Carman, Nikos Sparveris, E. Voutier, Misak Sargsian, M. Khandaker, L. Lanza, S. Niccolai, A. El Alaoui, Y. Ilieva, N. Compton, A. Movsisyan, M. Khachatryan, E. De Sanctis, Nicholas Zachariou, I. Bedlinskiy, W. K. Brooks, B. McKinnon, E. L. Isupov, M. Battaglieri, Iu. Skorodumina, P. Eugenio, M. Osipenko, M. Taiuti, R. A. Schumacher, Laura Clark, P. Lenisa, D. I. Sober, S. Boiarinov, M. L. Kabir, G. Charles, A. Kim, K. Livingston, M. Hattawy, A. D'Angelo, E. Golovatch, D. G. Jenkins, G. D. Smith, R. Dupre, N. Markov, Jie Zhang, M. Holtrop, Friedrich Klein, K. L. Giovanetti, Andrea Celentano, S. Stepanyan, Larry Weinstein, G. V. Fedotov, R. De Vita, C. Salgado, V. Batourine, L. El Fassi, P. Nadel-Turonski, N. Dashyan, G. Gavalian, V. Mokeev, Z. W. Zhao, R. Paremuzyan, Nicholas M. Harrison, F. X. Girod, L. Barion, S. Johnston, J. W. Price, M. Ripani, B. A. Clary, Michael Paolone, Barry Ritchie, A. I. Ostrovidov, K. Park, D. G. Ireland, Volker D. Burkert, A. S. Biselli, C. Djalali, J. A. Tan, D. Sokhan, W. Kim, C. Munoz Camacho, G. Niculescu, R. G. Fersch, P. L. Cole, M. Ungaro, H. Voskanyan, B. S. Ishkhanov, E. Pasyuk, V. P. Kubarovsky, D. Riser, O. Pogorelko, I. Balossino, G. Khachatryan, Dustin Keller, W. J. Briscoe, Michael Wood, K. Hafidi, L. Guo, Alessandro Rizzo, K. Hicks, W. Phelps, G. Rosner, and Y. Ghandilyan
Subjects: Vector Meson Dominance, Nuclear and High Energy Physics, Meson, Nuclear Theory, Socio-culturale, Double scattering, Photon energy, 01 natural sciences, 7. Clean energy, Settore FIS/04 - Fisica Nucleare e Subnucleare, Nuclear physics, Cross section (physics), 0103 physical sciences, 010306 general physics, Nuclear Experiment, Physics, Range (particle radiation), 010308 nuclear & particles physics, Scattering, Momentum transfer, Differential cross section, Single scattering, Vector meson dominance, lcsh:QC1-999, Deuterium, High Energy Physics::Experiment, lcsh:Physics
Abstract: The cross section for coherent ω-meson photoproduction off the deuteron has been measured for the first time as a function of the momentum transfer t=(Pγ−Pω)2 and photon energy Eγ using the CLAS detector at the Thomas Jefferson National Accelerator Facility. The cross sections are measured in the energy range 1.4
Published: 2018

39. Modified structure of protons and neutrons in correlated pairs

Author: R. A. Schumacher, S. E. Kuhn, J. W. Price, G. Ciullo, J. P. Ball, J. Zhang, D. Protopopescu, D. S. Carman, E. Voutier, A. Rizzo, Y. G. Sharabian, M. J. Amaryan, M. Bashkanov, C. E. Hyde, L. El Fassi, T. A. Forest, B. McKinnon, B. S. Ishkhanov, Taya Chetry, Avraham Klein, E. Golovatch, K. Livingston, H. Avakian, H. S. Jo, Or Hen, R. Dupre, Chaden Djalali, L. Barion, F. Hauenstein, T. Mineeva, M. Mirazita, R. De Vita, P. Eugenio, Y. Prok, H. Voskanyan, Avi Ashkenazi, Alexander Schmidt, A. Filippi, K. A. Griffioen, A. D'Angelo, Sergey Kuleshov, P. Lenisa, S. Stepanyan, M. L. Kabir, Latifa Elouadrhiri, M. Osipenko, S. Mey Tal Beck, Larry Weinstein, Y. Ilieva, E.P. Segarra, I. Bedlinskiy, T. B. Hayward, G. V. Fedotov, F. X. Girod, Martin Wood, B. Mustapha, A. Deur, Eli Piasetzky, Friedrich Klein, I. J. D. MacGregor, X. Zheng, E. De Sanctis, I. Balossino, S. Strauch, R. G. Fersch, G. Laskaris, A. Beck, P. L. Cole, W. K. Brooks, S. Adhikari, M. Khandaker, Eliahu Cohen, M. Duer, E. L. Isupov, Mark Strikman, K. Hicks, I. Korover, K. Park, M. Guidal, E. Pasyuk, N. Dashyan, M. Khachatryan, Shalev Gilad, G. Charles, Nicholas Zachariou, X. Wei, Nikolaos Sparveris, S. Joosten, M. Ripani, M. Holtrop, L. Guo, V. P. Kubarovsky, Michael Paolone, D. Riser, L. Lanza, Z. W. Zhao, H. Egiyan, M. Taiuti, C. Munoz Camacho, S. Niccolai, S. Boiarinov, A. I. Ostrovidov, C. Hanretty, F. Sabatié, D. G. Ireland, Douglas Higinbotham, M. Patsyuk, R. Paremuzyan, M. Battaglieri, David M. Keller, Volker D. Burkert, Nicholas M. Harrison, A. S. Biselli, Gerard Gilfoyle, D. Sokhan, D. P. Watts, K. Hafidi, W. Kim, K. Joo, R. Cruz-Torres, M. Ungaro, S. Diehl, C. Salgado, Andrea Celentano, N. Markov, R. W. Gothe, S. Johnston, B. Schmookler, O. Pogorelko, Victor Mokeev, V. Crede, R. A. Montgomery, H. Hakobyan, G. Khachatryan, W. J. Briscoe, P. Rossi, G. Rosner, I. u. Skorodumina, J. A. Tan, A. Kim, G. Gavalian, Institut de Recherches sur les lois Fondamentales de l'Univers (IRFU), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay, Institut de Physique Nucléaire d'Orsay (IPNO), Université Paris-Sud - Paris 11 (UP11)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS), CLAS, and Centre National de la Recherche Scientifique (CNRS)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Université Paris-Sud - Paris 11 (UP11)
Subjects: Quark, Nuclear Theory, Proton, nuclear physics: effect, nucleon: pair, EMC effect, Socio-culturale, FOS: Physical sciences, correlation: short-range, 01 natural sciences, symmetry breaking, Settore FIS/04 - Fisica Nucleare e Subnucleare, Nuclear physics, quark, Nuclear Theory (nucl-th), Experimental nuclear physics, Theoretical nuclear physics, High Energy Physics - Phenomenology (hep-ph), CLAS, 0103 physical sciences, quantum chromodynamics, Neutron, structure, Experimental nuclear physics, Nuclear Experiment (nucl-ex), 010306 general physics, Nuclear Experiment, quark gluon, Physics, Multidisciplinary, nucleon nucleon: correlation, 010308 nuclear & particles physics, precision measurement, High Energy Physics::Phenomenology, gluon, 3. Good health, Gluon, High Energy Physics - Phenomenology, Theoretical nuclear physics, [PHYS.HPHE]Physics [physics]/High Energy Physics - Phenomenology [hep-ph], Quark–gluon plasma, Atomic nucleus, Nucleon, experimental results
Abstract: The atomic nucleus is made of protons and neutrons (nucleons), that are themselves composed of quarks and gluons. Understanding how the quark-gluon structure of a nucleon bound in an atomic nucleus is modified by the surrounding nucleons is an outstanding challenge. Although evidence for such modification, known as the EMC effect, was first observed over 35 years ago, there is still no generally accepted explanation of its cause. Recent observations suggest that the EMC effect is related to close-proximity Short Range Correlated (SRC) nucleon pairs in nuclei. Here we report the first simultaneous, high-precision, measurements of the EMC effect and SRC abundances. We show that the EMC data can be explained by a universal modification of the structure of nucleons in neutron-proton (np) SRC pairs and present the first data-driven extraction of this universal modification function. This implies that, in heavier nuclei with many more neutrons than protons, each proton is more likely than each neutron to belong to an SRC pair and hence to have its quark structure distorted., Comment: Published in Nature. Total: 21 pages, 9 figures, 10 tables. Main text: 7 pages, 4 figures. Methods section: 1 page. Extended Data: 1 figure, 3 table. Supplementary Materials: 11 pages, 4 figures, 7 tables
Published: 2018

40. Measurement of the beam asymmetry Σ and the target asymmetry T in the photoproduction of ω mesons off the proton using CLAS at Jefferson Laboratory

Author: William Brooks, George Davey Smith, R. A. Schumacher, A. El Alaoui, S. Stepanyan, J. Pierce, H. Y. Lu, P. Eugenio, G. Gavalian, I. Denisenko, N. Dashyan, Taya Chetry, M. Taiuti, A. Filippi, A. Fradi, D. P. Watts, K. A. Griffioen, Friedrich Klein, V. Crede, M. Khandaker, D. G. Meekins, Brian Raue, A. D'Angelo, A. V. Sarantsev, Yordanka Ilieva, Nicholas Zachariou, E. Pasyuk, V. Mokeev, V. Batourine, R. Paremuzyan, R. De Vita, N. Markov, L. Lanza, G. Rosner, E. Golovatch, K. Hicks, W. Kim, Sergey Kuleshov, M. Ripani, R. A. Montgomery, F. Sabatié, S. Niccolai, Carlos A. Salgado, C. D. Keith, Pawel Nadel-Turonski, D. G. Jenkins, Eberhard Klempt, B. A. Clary, J. Brock, Alessandro Rizzo, R. Dupre, M. Battaglieri, J. Zhang, C. Djalali, J. A. Tan, L. El Fassi, J. W. Price, S. Anefalos Pereira, K. Livingston, C. Hanretty, C. Carlin, M. Guidal, L. Guo, M. Ungaro, Gerard Gilfoyle, A. I. Ostrovidov, A. V. Anisovich, K. Park, G. Charles, G. Niculescu, V. A. Nikonov, G. Ciullo, J. P. Ball, B. Torayev, Y. Prok, F. X. Girod, M. E. McCracken, D. S. Carman, D. G. Ireland, M. Holtrop, K. Joo, I. Bedlinskiy, V. P. Kubarovsky, D. Riser, M. Osipenko, Andreas Klein, Nikos Sparveris, X. Wei, T. Mineeva, D. Sokhan, O. Pogorelko, S. Procureur, W. Gohn, A. Kim, Z. E. Meziani, W. Phelps, Volker D. Burkert, M. Bashkanov, A. S. Biselli, B. S. Ishkhanov, L. Elouadrhiri, K. L. Giovanetti, I. Balossino, S. Strauch, Michael Dugger, D. I. Sober, E. Voutier, I. I. Strakovsky, A. Movsisyan, B. McKinnon, Dustin Keller, S. Park, A. Deur, K. Hafidi, Iu. Skorodumina, Sylvester Joosten, S. Fegan, G. Khachatryan, P. L. Cole, Z. W. Zhao, E. Phelps, N. Gevorgyan, D. Protopopescu, W. J. Briscoe, C. Munoz Camacho, M. H. Wood, A. Celentano, R. W. Gothe, M. Contalbrigo, Z. Akbar, N. K. Walford, I. J. D. MacGregor, S. Adhikari, M. Hattawy, Martin K. Mayer, Y. G. Sharabian, C. Gleason, Barry Ritchie, P. Roy, C. A. Meyer, G. V. Fedotov, E. L. Isupov, S. Boiarinov, K. P. Adhikari, H. Hakobyan, and P. Lenisa
Subjects: Physics, Particle physics, Proton, Meson, 010308 nuclear & particles physics, Partial wave analysis, media_common.quotation_subject, Nuclear Theory, Bremsstrahlung, Observable, 7. Clean energy, 01 natural sciences, Resonance (particle physics), Asymmetry, Baryon, Nuclear physics, 13. Climate action, 0103 physical sciences, High Energy Physics::Experiment, Nuclear Experiment, 010306 general physics, media_common
Abstract: The photoproduction of ω mesons off the proton has been studied in the reaction γp→pω using the CEBAF Large Acceptance Spectrometer (CLAS) and the frozen-spin target in Hall B at the Thomas Jefferson National Accelerator Facility. For the first time, the target asymmetry T has been measured in photoproduction from the decay ω→π+π-π0, using a transversely polarized target with energies ranging from just above the reaction threshold up to 2.8 GeV. Significant nonzero values are observed for these asymmetries, reaching about 30-40% in the third-resonance region. New measurements for the photon-beam asymmetry Σ are also presented, which agree well with previous CLAS results and extend the world database up to 2.1 GeV. These data and additional ω photoproduction observables from CLAS were included in a partial-wave analysis within the Bonn-Gatchina framework. Significant contributions from s-channel resonance production were found in addition to t-channel exchange processes.
Published: 2018

41. Measurement of the Q2 Dependence of the Deuteron Spin Structure Function g1 and its Moments at Low Q2 with CLAS

Author: I. Balossino, K. Kovacs, C. E. Hyde, Taya Chetry, P. Lenisa, Friedrich Klein, E. De Sanctis, D. G. Meekins, R. A. Schumacher, R. W. Gothe, L. El Fassi, Latifa Elouadrhiri, Y. Prok, Michael Paolone, L. Lanza, V. Crede, K. Park, C. A. Meyer, C. Munoz Camacho, J. Brock, G. V. Fedotov, J. P. Chen, K. Livingston, V. P. Kubarovsky, X. Zheng, A. D'Angelo, D. Heddle, B. McKinnon, M. Battaglieri, P. L. Cole, V. A. Drozdov, S. Bültmann, Maxime Defurne, G. Khachatryan, H. Avakian, M. Hattawy, J. A. Tan, K. P. Adhikari, N. Markov, M. Mirazita, Martin K. Mayer, H. Kang, K. Hafidi, S. Strauch, K. Joo, J. Pierce, Avraham Klein, K. Hicks, M. J. Amaryan, H. Hakobyan, J. W. Price, P. Bosted, H. S. Jo, W. Kim, M. Khachatryan, W. J. Briscoe, Nikolaos Sparveris, R. De Vita, M. Guidal, G. Niculescu, E. Pasyuk, K. A. Griffioen, G. E. Dodge, N. Dashyan, S. K. Phillips, C. Carlin, R. Paremuzyan, W. Phelps, A. Filippi, G. D. Smith, M. Holtrop, I. Bedlinskiy, M. Osipenko, Y. Ilieva, H. Egiyan, Larry Weinstein, D. Payette, E. L. Isupov, E. Golovatch, R. Dupre, Z. W. Zhao, I. J. D. MacGregor, P. Nadel-Turonski, Nicholas M. Harrison, Gerard Gilfoyle, S. E. Kuhn, F. Thanh Cao, S. Stepanyan, N. Guler, S. Johnston, D. Sokhan, Laura Clark, M. Ungaro, A. I. Ostrovidov, Luciano Pappalardo, E. Long, Sylvester Joosten, D. G. Jenkins, M. Khandaker, B. A. Raue, M. Contalbrigo, D. G. Ireland, Chaden Djalali, X. Wei, T. Shigeyuki, C. D. Keith, G. Rosner, Volker D. Burkert, P. Eugenio, M. Taiuti, S. Choi, T. Mineeva, A. S. Biselli, L. Guo, Y. Ghandilyan, P. Rossi, M. L. Kabir, S. Niccolai, A. El Alaoui, P. Konczykowski, Andrea Celentano, Karl Slifer, C. Salgado, L. Barion, J. Poudel, O. Pogorelko, C. Hanretty, M. Ripani, Z. Akbar, I. I. Strakovsky, A. Simonyan, G. Ciullo, J. P. Ball, D. S. Carman, A. Rizzo, A. Deur, A. Movsisyan, Victor Mokeev, J. Zhang, D. Protopopescu, S. Adhikari, E. Voutier, Y. G. Sharabian, G. Charles, V. Sulkosky, F. Sabatié, David M. Keller, and Iu. Skorodumina
Subjects: Physics, Quantum chromodynamics, Nuclear reaction, Chiral perturbation theory, Magnetic moment, 010308 nuclear & particles physics, General Physics and Astronomy, Spin structure, 01 natural sciences, Nuclear magnetic resonance, Polarizability, 0103 physical sciences, High Energy Physics::Experiment, Invariant mass, Atomic physics, Nuclear Experiment, 010306 general physics, Nucleon
Abstract: We measured the g 1 spin structure function of the deuteron at low Q 2 , where QCD can be approximated with chiral perturbation theory ( χ PT ). The data cover the resonance region, up to an invariant mass of W ≈ 1.9 GeV . The generalized Gerasimov-Drell-Hearn sum, the moment Γ d 1 and the spin polarizability γ d 0 are precisely determined down to a minimum Q 2 of 0.02 GeV 2 for the first time, about 2.5 times lower than that of previous data. We compare them to several χ PT calculations and models. These results are the first in a program of benchmark measurements of polarization observables in the χ PT domain.
Published: 2018

42. Measurement of Unpolarized and Polarized Cross Sections for Deeply Virtual Compton Scattering on the Proton at Jefferson Laboratory with CLAS

Author: F. Cao, W. Phelps, M. Guidal, E. Pasyuk, N. Dashyan, P. Lenisa, Andrea Celentano, M. Holtrop, S. Procureur, W. Gohn, S. E. Kuhn, G. Charles, M. J. Amaryan, H. S. Jo, H. Y. Lu, H. Voskanyan, B. McKinnon, Iu. Skorodumina, Friedrich Klein, Z. W. Zhao, A. I. Ostrovidov, R. A. Montgomery, Y. Prok, F. Sabatié, David M. Keller, Maxime Defurne, B. Guegan, K. A. Griffioen, H. Hakobyan, P. Stoler, A. Kim, M. Mirazita, A. El Alaoui, A. Filippi, N. Markov, A. Fradi, Latifa Elouadrhiri, X. Wei, G. Rosner, Taya Chetry, C. A. Meyer, I. Balossino, N. Gevorgyan, S. Johnston, K. L. Giovanetti, E. L. Isupov, G. V. Fedotov, K. Hicks, Y. Ghandilyan, Nicholas Zachariou, P. Eugenio, G. Niculescu, V. Batourine, D. G. Ireland, Sergey Kuleshov, M. Ripani, A. Deur, L. Guo, T. Mineeva, K. P. Adhikari, J. A. Tan, M. L. Kabir, S. Niccolai, Volker D. Burkert, W. K. Brooks, D. P. Watts, B. S. Ishkhanov, S. Adhikari, A. S. Biselli, D. Heddle, M. Battaglieri, C. Gleason, M. Khachatryan, D. G. Jenkins, M. Ungaro, R. De Vita, G. Khachatryan, E. Golovatch, R. Dupre, K. Park, Y. Ilieva, Nikolaos Sparveris, L. Lanza, R. W. Gothe, W. Kim, I. Bedlinskiy, K. Livingston, C. Munoz Camacho, M. Hattawy, R. A. Schumacher, M. Osipenko, P. Rossi, W. J. Briscoe, A. D'Angelo, R. G. Fersch, V. P. Kubarovsky, P. Nadel-Turonski, D. Riser, M. Khandaker, S. Stepanyan, R. Paremuzyan, K. Hafidi, S. Bültmann, T. A. Forest, P. L. Cole, Sylvester Joosten, O. Pogorelko, S. Diehl, S. Anefalos Pereira, Avraham Klein, Nicholas M. Harrison, Gerard Gilfoyle, J. W. Price, I. J. D. MacGregor, M. Contalbrigo, Martin Wood, C. Hanretty, L. Barion, C. Salgado, M. Taiuti, J. Zhang, D. Protopopescu, Victor Mokeev, Z. Akbar, M. Garçon, E. Voutier, Y. G. Sharabian, G. Ciullo, J. P. Ball, D. S. Carman, A. Rizzo, A. Movsisyan, L. El Fassi, Zein-Eddine Meziani, M. E. McCracken, F. X. Girod, O. Cortes, S. Boiarinov, Chaden Djalali, G. D. Smith, S. Strauch, G. Gavalian, B. A. Clary, N. Hirlinger Saylor, Michael Paolone, N. A. Baltzell, K. Joo, H. Egiyan, Institut de Physique Nucléaire d'Orsay (IPNO), Université Paris-Sud - Paris 11 (UP11)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS), Institut de Recherches sur les lois Fondamentales de l'Univers (IRFU), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay, CLAS, and Centre National de la Recherche Scientifique (CNRS)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Université Paris-Sud - Paris 11 (UP11)
Subjects: electron p: deep inelastic scattering, interference: Bethe-Heitler, Nuclear and High Energy Physics, generalized parton distribution, Proton, accelerator, electron: polarized beam, Hadronic Physics and QCD, FOS: Physical sciences, Socio-culturale, parton: distribution function, Parton, Newport News CEBAF Linac, [PHYS.NEXP]Physics [physics]/Nuclear Experiment [nucl-ex], momentum transfer dependence, 01 natural sciences, beam: energy, High Energy Physics - Experiment, Settore FIS/04 - Fisica Nucleare e Subnucleare, x-dependence, Nuclear physics, Cross section (physics), High Energy Physics - Experiment (hep-ex), spectrometer: acceptance, High Energy Physics - Phenomenology (hep-ph), deeply virtual Compton scattering, CLAS, 0103 physical sciences, [PHYS.HEXP]Physics [physics]/High Energy Physics - Experiment [hep-ex], Nuclear Experiment (nucl-ex), 010306 general physics, Nuclear Experiment, Quantum chromodynamics, Physics, Spectrometer, 010308 nuclear & particles physics, Compton scattering, cross section: difference, HERA, magnetic spectrometer, photon: electroproduction, High Energy Physics - Phenomenology, kinematics, [PHYS.HPHE]Physics [physics]/High Energy Physics - Phenomenology [hep-ph], Nucleon, channel cross section: measured, experimental results
Abstract: This paper reports the measurement of polarized and unpolarized cross sections for the ep -> e'p' reaction, which is comprised of Deeply Virtual Compton Scattering (DVCS) and Bethe-Heitler (BH) processes, at an electron beam energy of 5.88 GeV at the Thomas Jefferson National Accelerator Facility using the Large Acceptance Spectrometer CLAS. The unpolarized cross sections and polarized cross section differences have been measured over broad kinematics, 0.10 < x_B < 0.58, 1.0 < Q^2 < 4.8 GeV^2, and 0.09 < -t < 2.00 GeV^2. The results are found to be consistent with previous CLAS data, and these new data are discussed in the framework of the generalized parton distribution approach. Calculations with two widely used phenomenological models, denoted VGG and KMSC, are approximately compatible with the experimental results over a large portion of the kinematic range of the data., 27 pages, 24 figures, Accepted for publication in PRC
Published: 2018

43. First measurement of $\Xi^-$ polarization in photoproduction

Author: K. Livingston, M. Hattawy, Taya Chetry, Jie Zhang, A. Kim, L. Guo, Alessandro Rizzo, W. Kim, G. Niculescu, R. Paremuzyan, Lorenzo Zana, N. Dashyan, Nicholas M. Harrison, R. A. Schumacher, Maxime Defurne, Yordanka Ilieva, C. Djalali, J. A. Tan, K. A. Griffioen, C. Salgado, V. Crede, D. Sokhan, D. I. Glazier, L. Barion, P. Eugenio, Michael Dugger, R. A. Montgomery, R. De Vita, E. Golovatch, A. El Alaoui, M. Taiuti, Nicholas Zachariou, M. Osipenko, J. Bono, A. Fradi, M. L. Kabir, H. Egiyan, F. Cao, I. Bedlinskiy, Iu. Skorodumina, S. Stepanyan, G. Charles, M. Ungaro, E. L. Isupov, B. A. Clary, C. Munoz Camacho, G. Rosner, X. Wei, P. Lenisa, Y. Prok, S. Strauch, M. Battaglieri, F. Sabatié, W. Gohn, D. Protopopescu, Z. W. Zhao, N. Markov, K. Hicks, M. Bashkanov, S. Adhikari, B. McKinnon, W. Phelps, G. D. Smith, M. Holtrop, N. Gevorgyan, Avraham Klein, Y. Ghandilyan, Michael Paolone, A. Celentano, R. W. Gothe, I. I. Strakovsky, E. Voutier, Rong Wang, A. Deur, M. Khachatryan, G. Ciullo, J. P. Ball, M. C. Kunkel, A. I. Ostrovidov, K. Park, D. S. Carman, G. V. Fedotov, Nikos Sparveris, D. G. Ireland, Friedrich Klein, V. Batourine, Volker D. Burkert, A. S. Biselli, T. Mineeva, William Brooks, Brian Raue, K. P. Adhikari, F. X. Girod, G. Gavalian, Y. G. Sharabian, S. Johnston, M. Ripani, H. S. Jo, G. Khachatryan, M. Contalbrigo, J. W. Price, Z. Akbar, I. J. D. MacGregor, V. P. Kubarovsky, A. D'Angelo, O. Pogorelko, L. El Fassi, Dustin Keller, Michael Wood, K. Hafidi, M. J. Amaryan, P. L. Cole, H. Voskanyan, D. Heddle, E. Pasyuk, S. Diehl, A. Filippi, M. Khandaker, Institut de Recherches sur les lois Fondamentales de l'Univers (IRFU), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay, Institut de Physique Nucléaire d'Orsay (IPNO), Université Paris-Sud - Paris 11 (UP11)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS), CLAS, Institut de Recherches sur les lois Fondamentales de l'Univers ( IRFU ), Commissariat à l'énergie atomique et aux énergies alternatives ( CEA ) -Université Paris-Saclay, Institut de Physique Nucléaire d'Orsay ( IPNO ), Université Paris-Sud - Paris 11 ( UP11 ) -Institut National de Physique Nucléaire et de Physique des Particules du CNRS ( IN2P3 ) -Centre National de la Recherche Scientifique ( CNRS ), and Centre National de la Recherche Scientifique (CNRS)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Université Paris-Sud - Paris 11 (UP11)
Subjects: Nuclear and High Energy Physics, Photon, Meson, Hadron, Nuclear Theory, Cascade, Hyperon spectroscopy, Photoproduction, Polarization, Strange, Xi, Socio-culturale, Elementary particle, Xi-: polarization, Photon energy, [PHYS.NEXP]Physics [physics]/Nuclear Experiment [nucl-ex], 01 natural sciences, Computer Science::Digital Libraries, Settore FIS/04 - Fisica Nucleare e Subnucleare, Nuclear physics, photoproduction: (cascade), Particle decay, polarization: measured, excited state: spectrum, CLAS, meson: exchange, 0103 physical sciences, Xi-: photoproduction, [ PHYS.NEXP ] Physics [physics]/Nuclear Experiment [nucl-ex], 010306 general physics, Nuclear Experiment, Physics, 010308 nuclear & particles physics, Hyperon, hyperon: (nucleon resonance), photon: energy, Baryon, Xi-: (recoil), High Energy Physics::Experiment, polarization: induced, hyperon: photoproduction, decay: weak interaction, +K%2B+K-+Xi%22">photon p --> K+ K- Xi, 5.45 GeV, Jefferson Lab
Abstract: Despite decades of studies of the photoproduction of hyperons, both their production mechanisms and their spectra of excited states are still largely unknown. While the parity-violating weak decay of hyperons offers a means of measuring their polarization, which could help discern their production mechanisms and identify their excitation spectra, no such study has been possible for doubly strange baryons in photoproduction, due to low production cross sections. However, by making use of the reaction $\gamma p \to K^+ K^+ \Xi^-$, we have measured, for the first time, the induced polarization, $P$, and the transferred polarization from circularly polarized real photons, characterized by $C_x$ and $C_z$, to recoiling $\Xi^-$s. The data were obtained using the CEBAF Large Acceptance Spectrometer (CLAS) at Jefferson Lab for photon energies from just over threshold (2.4 GeV) to 5.45 GeV. These first-time measurements are compared, and are shown to broadly agree, with model predictions in which cascade photoproduction proceeds through the decay of intermediate hyperon resonances that are produced via relativistic meson exchange, offering a new step forward in the understanding of the production and polarization of doubly-strange baryons., Comment: 9 pages, 7 figures
Published: 2018

44. Probing high-momentum protons and neutrons in neutron-rich nuclei

Author: D. Bulumulla, B. S. Ishkhanov, B. A. Clary, C. E. Hyde, T. Mineeva, Adi Ashkenazi, P. Eugenio, Alexander Schmidt, K. Livingston, Pawel Nadel-Turonski, M. Taiuti, J. Arrington, Y. Prok, A. I. Ostrovidov, G. Gavalian, M. Contalbrigo, Michael Paolone, R. A. Schumacher, M. L. Kabir, A. D'Angelo, C. Munoz-Camacho, A. Beck, G. Ciullo, J. P. Ball, G. Laskaris, D. S. Carman, L. Lanza, Shalev Gilad, G. Khachatryan, A. Rizzo, F. Hauenstein, D. G. Ireland, R. G. Fersch, E. De Sanctis, S. Mey-Tal Beck, A. Movsisyan, M. Battaglieri, P. L. Cole, Z. W. Zhao, S. Stepanyan, George Davey Smith, Volker D. Burkert, A. S. Biselli, G. Charles, Nicholas M. Harrison, Gerard Gilfoyle, Y. Ilieva, Andreas Klein, J. Poudel, D. Sokhan, M. Patsyuk, K. Hicks, D. P. Watts, Taya Chetry, B. McKinnon, H. Egiyan, S. Nadeeshani, X. Wei, P. Lenisa, N. Markov, W. J. Briscoe, W. Kim, K. P. Adhikari, Douglas Higinbotham, M. Mirazita, Maxime Defurne, R. Cruz-Torres, I. Bedlinskiy, S. Niccolai, Chaden Djalali, M. Osipenko, L. El Fassi, L. Guo, D. Payette, Or Hen, Eliahu Cohen, K.A. Griffoen, B. Schmookler, M. Braverman, L. Barion, R. De Vita, A. El Alaoui, G. E. Dodge, Andrea Celentano, K. Hafidi, M. Khandaker, S. Procureur, Friedrich Klein, T. A. Forest, F. X. Girod, M. J. Amaryan, Nicholas Zachariou, F. Cao, M. Ripani, I. J. D. MacGregor, E.P. Segarra, Eli Piasetzky, I. Korover, Afroditi Papadopoulou, S. Strauch, J. W. Price, G. Rosner, A. Filippi, M. Duer, K. L. Giovanetti, O. Pogorelko, Larry Weinstein, B. Mustapha, G. Niculescu, E. Pasyuk, W. Phelps, N. Dashyan, E. L. Isupov, O. Cortes, R. W. Gothe, S. Boiarinov, Y. Ghandilyan, M. Holtrop, S. Bueltmann, Victor Mokeev, M. Ungaro, J. Zhang, D. Protopopescu, K. Joo, E. Voutier, Y. G. Sharabian, A. Kim, William Brooks, C. Marchand, V. Batourine, F. Sabatié, David M. Keller, J. A. Tan, V. Crede, R. A. Montgomery, H. Hakobyan, Laura Clark, P. Rossi, X. Zheng, M. Khachatryan, Nikolaos Sparveris, S. E. Kuhn, M. Hattawy, A. Deur, S. Adhikari, E. Golovatch, R. Dupre, K. Park, I. Balossino, H. Voskanyan, Carlos A. Salgado, Institut de Recherches sur les lois Fondamentales de l'Univers (IRFU), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay, Institut de Physique Nucléaire d'Orsay (IPNO), Université Paris-Sud - Paris 11 (UP11)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS), CLAS, and Centre National de la Recherche Scientifique (CNRS)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Université Paris-Sud - Paris 11 (UP11)
Subjects: Quark, Multidisciplinary matter, Proton, [PHYS.NUCL]Physics [physics]/Nuclear Theory [nucl-th], Astrophysics::High Energy Astrophysical Phenomena, EMC effect, Nuclear Theory, momentum spectrum, Socio-culturale, parton: distribution function, Electron, 7. Clean energy, 01 natural sciences, nucleon: momentum, Settore FIS/04 - Fisica Nucleare e Subnucleare, Nuclear physics, CLAS, 0103 physical sciences, Neutron, 010306 general physics, Nuclear Experiment, neutron star, p nucleus: scattering, Physics, Multidisciplinary, 010308 nuclear & particles physics, electron nucleus: scattering, quantum mechanics, Nuclear shell model, shell model, correlation, Atomic nucleus, Nucleon
Abstract: International audience; The atomic nucleus is one of the densest and most complex quantum-mechanical systems in nature. Nuclei account for nearly all the mass of the visible Universe. The properties of individual nucleons (protons and neutrons) in nuclei can be probed by scattering a high-energy particle from the nucleus and detecting this particle after it scatters, often also detecting an additional knocked-out proton. Analysis of electron- and proton-scattering experiments suggests that some nucleons in nuclei form close-proximity neutron–proton pairs 1$^{–}$12 with high nucleon momentum, greater than the nuclear Fermi momentum. However, how excess neutrons in neutron-rich nuclei form such close-proximity pairs remains unclear. Here we measure protons and, for the first time, neutrons knocked out of medium-to-heavy nuclei by high-energy electrons and show that the fraction of high-momentum protons increases markedly with the neutron excess in the nucleus, whereas the fraction of high-momentum neutrons decreases slightly. This effect is surprising because in the classical nuclear shell model, protons and neutrons obey Fermi statistics, have little correlation and mostly fill independent energy shells. These high-momentum nucleons in neutron-rich nuclei are important for understanding nuclear parton distribution functions (the partial momentum distribution of the constituents of the nucleon) and changes in the quark distributions of nucleons bound in nuclei (the EMC effect) 1$^{,}$13$^{,}$14 . They are also relevant for the interpretation of neutrino-oscillation measurements 15 and understanding of neutron-rich systems such as neutron stars 3$^{,}$16 .
Published: 2018

45. Double $K_S^0$ Photoproduction off the Proton at CLAS

Author: W. Gohn, Pawel Nadel-Turonski, R. Paremuzyan, R. A. Schumacher, N. Markov, P. Eugenio, Nicholas M. Harrison, D. G. Jenkins, Gerard Gilfoyle, D. Sokhan, E. Golovatch, R. Dupre, I. Bedlinskiy, M. L. Kabir, L. Lanza, C. Munoz Camacho, M. Battaglieri, M. Bashkanov, B. McKinnon, X. Wei, C. A. Meyer, F. X. Girod, Y. Ilieva, G. V. Fedotov, H. Egiyan, L. Guo, A. D'Angelo, C. Hanretty, S. Niccolai, I. I. Strakovsky, P. Lenisa, K. P. Adhikari, Chaden Djalali, Avraham Klein, A. Simonyan, A. Deur, Laura Clark, E. De Sanctis, Iu. Skorodumina, G. Khachatryan, W. Kim, K. Park, W. Phelps, Sylvester Joosten, A. Fradi, K. Joo, W. J. Briscoe, G. Charles, M. Osipenko, Barry Ritchie, W. K. Brooks, S. Adhikari, Friedrich Klein, Brian Raue, J. Zhang, D. Protopopescu, E. Voutier, Y. G. Sharabian, S. Chandavar, S. Strauch, Y. Prok, T. Mineeva, G. Ciullo, J. P. Ball, D. S. Carman, Maxime Defurne, V. Crede, A. Rizzo, G. Rosner, G. Gavalian, F. Sabatié, D. I. Glazier, K. A. Griffioen, M. C. Kunkel, S. Johnston, David M. Keller, V. P. Kubarovsky, Y. Ghandilyan, Carlos A. Salgado, M. Khachatryan, R. De Vita, K. Livingston, M. Hattawy, K. Hicks, A. Movsisyan, E. L. Isupov, D. Riser, H. Hakobyan, Nikolaos Sparveris, Michael Paolone, M. Khandaker, A. I. Ostrovidov, D. G. Ireland, S. Stepanyan, Volker D. Burkert, A. S. Biselli, Andrea Celentano, A. El Alaoui, Nicholas Zachariou, M. Ripani, F. Cao, M. Guidal, G. Niculescu, E. Pasyuk, N. Dashyan, M. Holtrop, D. P. Weygand, I. Balossino, Taya Chetry, George Davey Smith, J. W. Price, M. Ungaro, L. El Fassi, M. Contalbrigo, Z. Akbar, O. Pogorelko, I. J. D. MacGregor, P. L. Cole, Z. W. Zhao, M. E. McCracken, Victor Mokeev, R. W. Gothe, L. Barion, A. Filippi, D. Heddle, K. Hafidi, J. T. Goetz, Institut de Recherches sur les lois Fondamentales de l'Univers (IRFU), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay, Institut de Physique Nucléaire d'Orsay (IPNO), Centre National de la Recherche Scientifique (CNRS)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Université Paris-Sud - Paris 11 (UP11), CLAS, Université Paris-Sud - Paris 11 (UP11)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS), Institut de Recherches sur les lois Fondamentales de l'Univers ( IRFU ), Commissariat à l'énergie atomique et aux énergies alternatives ( CEA ) -Université Paris-Saclay, Institut de Physique Nucléaire d'Orsay ( IPNO ), and Université Paris-Sud - Paris 11 ( UP11 ) -Institut National de Physique Nucléaire et de Physique des Particules du CNRS ( IN2P3 ) -Centre National de la Recherche Scientifique ( CNRS )
Subjects: Nuclear and High Energy Physics, Meson, Proton, Dalitz plot, FOS: Physical sciences, Socio-culturale, Photon energy, [PHYS.NEXP]Physics [physics]/Nuclear Experiment [nucl-ex], time-of-flight, 01 natural sciences, Resonance (particle physics), Settore FIS/04 - Fisica Nucleare e Subnucleare, Nuclear physics, mass spectrum, p: target, background: low, CLAS, 0103 physical sciences, mixing, Invariant mass, Nuclear Experiment (nucl-ex), [ PHYS.NEXP ] Physics [physics]/Nuclear Experiment [nucl-ex], 010306 general physics, Nuclear Experiment, Physics, 010308 nuclear & particles physics, Glueball, background, meson resonance, photon: energy, momentum transfer: measured, Automatic Keywords, glueball, meson: photoproduction, Mass spectrum, baryon: hadron spectroscopy, High Energy Physics::Experiment, missing-mass, photoproduction, experimental results
Abstract: The $f_0$(1500) meson resonance is one of several contenders to have significant mixing with the lightest glueball. This resonance is well established from several previous experiments. Here we present the first photoproduction data for the $f_0$(1500) via decay into the $K_S^0 K_S^0$ channel using the CLAS detector. The reaction $��p$ -> $f_0 p$ -> $K_S^0 K_S^0 p$, where J = 0, 2, was measured with photon energies from 2.7 to 5.1 GeV. A clear peak is seen at 1500 MeV in the background subtracted invariant mass spectra of the two kaons. This is enhanced if the measured 4-momentum transfer to the proton target is restricted to be less than 1.0 GeV2. By comparing data with simulations, it can be concluded that the peak at 1500 MeV is produced primarily at low t, which is consistent with a t-channel production mechanism., 12 pages, 12 figures
Published: 2018

46. Measurement of the helicity asymmetry E in ω→π+π−π0 photoproduction

Author: M. Contalbrigo, T. Mineeva, R. A. Schumacher, Z. Akbar, M. Khachatryan, V. Mokeev, Taya Chetry, A. V. Anisovich, G. Ciullo, J. P. Ball, Y. Prok, D. S. Carman, E. Golovatch, F. Cao, P. Roy, M. Guidal, B. S. Ishkhanov, K. Hicks, C. Gleason, Iu. Skorodumina, Nikos Sparveris, X. Wei, M. Holtrop, O. Cortes, K. P. Adhikari, C. D. Keith, E. L. Isupov, M. Ripani, Barry Ritchie, E. Voutier, Nicholas Zachariou, S. Stepanyan, Laura Clark, L. Guo, H. Egiyan, S. Boiarinov, G. Khachatryan, A. Movsisyan, I. J. D. MacGregor, E. De Sanctis, G. Charles, J. Brock, Sylvester Joosten, M. Hattawy, Carlos A. Salgado, A. Celentano, R. W. Gothe, A. V. Sarantsev, S. Park, M. Osipenko, F. Sabatié, W. J. Briscoe, I. I. Strakovsky, Y. G. Sharabian, S. Niccolai, M. Ungaro, D. I. Sober, A. I. Ostrovidov, K. Park, Michael Paolone, R. Dupre, M. Battaglieri, C. Munoz Camacho, A. Filippi, G. V. Fedotov, A. Deur, K. A. Griffioen, V. Crede, D. G. Ireland, W. Phelps, Lorenzo Zana, S. Adhikari, N. Dashyan, D. Protopopescu, Alessandro Rizzo, M. Garçon, Volker D. Burkert, B. McKinnon, W. K. Brooks, D. G. Jenkins, I. Bedlinskiy, V. A. Nikonov, Brian Raue, P. Nadel-Turonski, A. Fradi, F. X. Girod, W. Kim, I. Denisenko, V. Batourine, Michael Dugger, G. Rosner, N. Markov, R. Paremuzyan, S. Strauch, Andreas Klein, K. Livingston, W. Gohn, R. De Vita, C. Carlin, Nicholas M. Harrison, S. Anefalos Pereira, L. Lanza, D. Sokhan, A. Kim, C. Djalali, C. Hanretty, R. Fersch, H. Avakian, Eberhard Klempt, J. Zhang, H. Voskanyan, E. Pasyuk, J. W. Price, George Davey Smith, V. P. Kubarovsky, D. G. Meekins, A. D'Angelo, O. Pogorelko, Frank Klein, Dustin Keller, L. El Fassi, Michael Wood, K. Hafidi, P. L. Cole, Z. W. Zhao, P. Eugenio, M. Taiuti, N. Gevorgyan, D. Heddle, G. Hollis, Hrachya Hakobyan, M. J. Amaryan, K. L. Giovanetti, and M. Khandaker
Subjects: Physics, Meson, 010308 nuclear & particles physics, Partial wave analysis, Bremsstrahlung, Resonance, Observable, 01 natural sciences, Helicity, Nuclear physics, Pomeron, 0103 physical sciences, Nuclear Experiment, 010306 general physics, Nucleon
Abstract: The double-polarization observable E was studied for the reaction γp → pω using the CEBAF Large Acceptance Spectrometer (CLAS) in Hall B at the Thomas Jefferson National Accelerator Facility and the longitudinally polarized frozen-spin target (FROST). The observable was measured from the charged decay mode of the meson, ω → π+π−π0, using a circularly polarized tagged-photon beam with energies ranging from the ω threshold at 1.1 to 2.3 GeV. A partial-wave analysis within the Bonn-Gatchina framework found dominant contributions from the 3/2+ partial wave near threshold, which is identified with the subthreshold N(1720) 3/2+ nucleon resonance. To describe the entire data set, which consisted of ω differential cross sections and a large variety of polarization observables, further contributions from other nucleon resonances were found to be necessary. With respect to nonresonant mechanisms, π exchange in the t channel was found to remain small across the analyzed energy range, while Pomeron t-channel exchange gradually grew from the reaction threshold to dominate all other contributions above W ≈ 2 GeV.
Published: 2017

47. Determination of the proton spin structure functions for 0.05<Q2<5GeV2 using CLAS

Author: N. Harrison, V. Crede, Y. Prok, A. Simonyan, R. A. Montgomery, P. Lenisa, N. Zachariou, H. Egiyan, L. Clark, N. K. Walford, M. Ungaro, N. Dashyan, R. W. Gothe, A. D'Angelo, G. P. Gilfoyle, C. Salgado, L. Colaneri, P. Bosted, P. Eugenio, I. Balossino, R. G. Fersch, Friedrich Klein, E. L. Isupov, M. Taiuti, W. Phelps, M. Contalbrigo, G. Gavalian, F. Cao, K. Hicks, G. Murdoch, P. Roy, M. Guidal, Taya Chetry, G. E. Dodge, C. Hanretty, M. Khandaker, M. Holtrop, M. Garçon, K. Hafidi, I. Bedlinskiy, J. A. Fleming, J. Ball, M. Hattawy, M. Osipenko, Iu. Skorodumina, B. S. Ishkhanov, D. Protopopescu, D. Heddle, D. Keller, Z. Akbar, Marco Ripani, J. Zhang, Michael Paolone, C. Djalali, C. A. Meyer, E. Voutier, G. V. Fedotov, O. Cortes, D. P. Watts, K. Griffioen, H. Voskanyan, V. Kubarovsky, C. Keith, W. K. Brooks, P. Rossi, Ye Tian, F. Sabatié, L. B. Weinstein, S. L. Careccia, I. I. Strakovsky, A. Rizzo, A. Deur, C. Gleason, R. Paremuzyan, W. Kim, D. Sokhan, S. Pisano, L. Elouadrhiri, G. Niculescu, S. E. Kuhn, D. Riser, A. El Alaoui, S. Stepanyan, O. Pogorelko, H. Avakian, B. A. Raue, A. I. Ostrovidov, G. Asryan, D. G. Ireland, Y. Ilieva, Volker D. Burkert, A. S. Biselli, R. Dupre, K. L. Giovanetti, G. Ciullo, D. A. Jenkins, K. Livingston, D. S. Carman, Nikos Sparveris, S. Niccolai, X. Wei, L. Lanza, V. G. Lagerquist, B. Torayev, E. Pasyuk, I. Stankovic, A. Movsisyan, N. Guler, M. Mirazita, C. Munoz Camacho, N. Compton, Hrachya Hakobyan, B. McKinnon, E. De Sanctis, A. Klein, H. Y. Lu, R. De Vita, S. Anefalos Pereira, K. Joo, S. Chandavar, A. Filippi, M. J. Amaryan, E. Fanchini, L. Guo, J. W. Price, S. M. Hughes, R. Minehart, R. A. Schumacher, V. Mokeev, K. P. Adhikari, T. A. Forest, J. Pierce, S. Bultmann, E. Golovatch, P. Nadel-Turonski, I. Niculescu, S. Adhikari, G. Khachatryan, W. J. Briscoe, G. Charles, L. El Fassi, P. L. Cole, Andrea Celentano, A. Kim, G. D. Smith, F. X. Girod, S. Strauch, M. Khachatryan, Y. G. Sharabian, G. Rosner, N. A. Baltzell, Y. Ghandilyan, K. Park, and M. Battaglieri
Subjects: Quantum chromodynamics, Physics, Particle physics, Proton, 010308 nuclear & particles physics, Virtual particle, Parton, Deep inelastic scattering, 01 natural sciences, Nuclear physics, 0103 physical sciences, Proton spin crisis, High Energy Physics::Experiment, Operator product expansion, Nuclear Experiment, 010306 general physics, Spin-½
Abstract: We present the results of our final analysis of the full data set of g1p(Q2), the spin structure function of the proton, collected using CLAS at Jefferson Laboratory in 2000–2001. Polarized electrons with energies of 1.6, 2.5, 4.2, and 5.7 GeV were scattered from proton targets (NH315 dynamically polarized along the beam direction) and detected with CLAS. From the measured double spin asymmetries, we extracted virtual photon asymmetries A1p and A2p and spin structure functions g1p and g2p over a wide kinematic range (0.05 GeV2
Published: 2017

48. Measurement of the differential and total cross sections of the γd→K0Λ(p) reaction within the resonance region

Author: H. Hakobyan, M. Taiuti, Dustin Keller, N. Compton, N. Dashyan, D. I. Glazier, R. De Vita, Michael Wood, K. Hafidi, Laura Clark, Yordanka Ilieva, X. Wei, C. E. Hyde, A. Simonyan, M. Osipenko, L. Guo, Alessandro Rizzo, S. Anefalos Pereira, K. Hicks, R. Paremuzyan, R. A. Schumacher, W. Phelps, V. P. Kubarovsky, V. Crede, A. El Alaoui, J. A. Fleming, O. Pogorelko, S. M. Hughes, P. Nadel-Turonski, G. Murdoch, R. A. Montgomery, Michael Paolone, G. Gavalian, N. K. Walford, M. Camp, G. Charles, V. Mokeev, C. Gleason, Nicholas Zachariou, E. De Sanctis, K. P. Adhikari, Nicholas M. Harrison, T. Cao, H. Avakian, H. S. Jo, F. X. Girod, N. Markov, I. J. D. MacGregor, D. Heddle, C. Hanretty, Barry Ritchie, H. Voskanyan, S. Pisano, P. Lenisa, M. Contalbrigo, Avraham Klein, D. Sokhan, F. Sabatié, H. Y. Lu, G. Rosner, M. Khachatryan, I. Stankovic, Philip L. Cole, Z. Akbar, S. Adhikari, B. McKinnon, Nikolaos Sparveris, I. Bedlinskiy, E. Munevar, W. Kim, P. L. Cole, K. Livingston, Y. Ghandilyan, I. Niculescu, Friedrich Klein, D. G. Jenkins, G. Niculescu, B. S. Ishkhanov, A. D'Angelo, Taya Chetry, R. W. Gothe, Eberhard Klempt, M. Mirazita, L. El Fassi, V. Batourine, J. Zhang, S. Stepanyan, G. Khachatryan, Brian Raue, J. W. Price, Latifa Elouadrhiri, C. A. Meyer, Sergey Kuleshov, M. Ripani, M. Ungaro, A. I. Ostrovidov, K. Park, G. V. Fedotov, F. Cao, D. G. Ireland, V. A. Nikonov, Volker D. Burkert, A. S. Biselli, W. J. Briscoe, K. Joo, C. Munoz Camacho, I. I. Strakovsky, M. Guidal, Y. G. Sharabian, G. Ciullo, Y. Prok, T. Mineeva, D. S. Carman, D. Protopopescu, A. Deur, E. Voutier, S. Niccolai, A. Movsisyan, Iu. Skorodumina, W. K. Brooks, G. D. Smith, M. Holtrop, C. E. Taylor, E. Golovatch, R. Dupre, S. Strauch, D. P. Watts, H. Egiyan, A. V. Sarantsev, M. Battaglieri, B. Torayev, K. L. Giovanetti, A. Filippi, M. Khandaker, O. Cortes, E. L. Isupov, A. Fradi, Sylvester Joosten, L. Lanza, Eugene Pasyuk, Andrea Celentano, C. Djalali, N. A. Baltzell, C. Salgado, K. A. Griffioen, A. Trivedi, and P. Eugenio
Subjects: Physics, Particle physics, 010308 nuclear & particles physics, Partial wave analysis, Quark model, Gamma ray, Bremsstrahlung, Resonance, Lambda, 01 natural sciences, Particle identification, Nuclear physics, 0103 physical sciences, High Energy Physics::Experiment, Nuclear Experiment, 010306 general physics, Nucleon
Abstract: We report the first measurement of differential and total cross sections for the $\ensuremath{\gamma}d\ensuremath{\rightarrow}{K}^{0}\mathrm{\ensuremath{\Lambda}}(p)$ reaction, using data from the CLAS detector at the Thomas Jefferson National Accelerator Facility. Data collected during two separate experimental runs were studied with photon-energy coverage 0.8--3.6 GeV and 0.5-- 2.6 GeV, respectively. The two measurements are consistent giving confidence in the method and determination of systematic uncertainties. The cross sections are compared with predictions from the KAON-MAID theoretical model (without kaon exchange), which deviate from the data at higher $W$ and at forward kaon angles. These data, along with previously published cross sections for ${K}^{+}\mathrm{\ensuremath{\Lambda}}$ photoproduction, provide essential constraints on the nucleon resonance spectrum. A first partial wave analysis was performed that describes the data without the introduction of new resonances.
Published: 2017

49. First Exclusive Measurement of Deeply Virtual Compton Scattering off He4 : Toward the 3D Tomography of Nuclei

Author: M. J. Amaryan, Laura Clark, C. Gleason, P. Lenisa, W. Phelps, H. Moutarde, X. Wei, K. A. Griffioen, B. S. Ishkhanov, K. L. Giovanetti, Taya Chetry, M. Hattawy, Hovanes Egiyan, Larry Weinstein, G. Ciullo, J. P. Ball, Y. Prok, D. S. Carman, P. Eugenio, E. Golovatch, S. Strauch, J. W. Price, Friedrich Klein, L. Guo, Alessandro Rizzo, C. Munoz Camacho, D. G. Ireland, E. Voutier, Latifa Elouadrhiri, R. De Vita, V. Crede, M. Taiuti, C. Djalali, Michael Paolone, A. Movsisyan, O. Cortes, E. L. Isupov, S. Niccolai, Z. W. Zhao, C. A. Meyer, H. Y. Lu, L. Lanza, Whitney Armstrong, A. I. Ostrovidov, K. Park, G. V. Fedotov, D. P. Watts, G. Rosner, R. A. Montgomery, A. Celentano, Martin K. Mayer, R. W. Gothe, K. Livingston, A. Deur, H. Jiang, Volker D. Burkert, A. S. Biselli, D. G. Jenkins, R. Paremuzyan, Sergey Kuleshov, M. Khachatryan, A. Simonyan, Y. Ghandilyan, V. I. Mokeev, D. Heddle, H. Hakobyan, M. H. Wood, R. Dupre, S. Boiarinov, L. Colaneri, Iu. Skorodumina, S. Adhikari, S. Anefalos Pereira, S. Fegan, Jie Zhang, I. Niculescu, F. Cao, E. Pasyuk, Nikolaos Sparveris, N. Markov, K. Hicks, D. Adikaram, B. Torayev, M. Guidal, G. Charles, F. X. Girod, Z. E. Meziani, Nicholas M. Harrison, Gerard Gilfoyle, I. Bedlinskiy, N. A. Baltzell, C. Hanretty, W. Kim, P. Nadel-Turonski, William Brooks, A. Filippi, G. D. Smith, M. Holtrop, Lorenzo Zana, G. Khachatryan, M. Battaglieri, G. Niculescu, E. Seder, R. G. Fersch, F. Sabatié, W. Gohn, P. Rossi, V. P. Kubarovsky, D. Sokhan, P. L. Cole, M. Khandaker, O. Pogorelko, D. Protopopescu, B. G. Ritchie, M. Bashkanov, R. A. Schumacher, M. Ungaro, S. M. Hughes, M. Garçon, N. Dashyan, A. D'Angelo, E. De Sanctis, Sylvester Joosten, B. McKinnon, M. E. McCracken, L. A. Net, L. El Fassi, C. Salgado, M. Osipenko, Dustin Keller, A. El Alaoui, N. K. Walford, Y. Perrin, T. Mineeva, Nicholas Zachariou, S. Bültmann, M. Mirazita, E. Phelps, K. P. Adhikari, T. A. Forest, K. Hafidi, N. Gevorgyan, I. J. D. MacGregor, V. Batourine, H. Avakian, S. Stepanyan, Y. G. Sharabian, S. Pisano, K. Joo, Simonetta Liuti, Avraham Klein, M. Contalbrigo, H. Voskanyan, A. Kim, W. J. Briscoe, A. Fradi, S. E. Kuhn, J. A. Fleming, Z. Akbar, and M. Ripani
Subjects: Physics, Particle physics, Time projection chamber, Photon, Proton, Meson, 010308 nuclear & particles physics, Compton scattering, General Physics and Astronomy, Electron, HERA, 01 natural sciences, 7. Clean energy, Nuclear physics, Recoil, 0103 physical sciences, Physics::Accelerator Physics, Nuclear Experiment, 010306 general physics
Abstract: We report on the first measurement of the beam-spin asymmetry in the exclusive process of coherent deeply virtual Compton scattering off a nucleus. The experiment uses the 6 GeV electron beam from the Continuous Electron Beam Accelerator Facility (CEBAF) accelerator at Jefferson Lab incident on a pressurized $^{4}\mathrm{He}$ gaseous target placed in front of the CEBAF Large Acceptance Spectrometer (CLAS). The scattered electron is detected by CLAS and the photon by a dedicated electromagnetic calorimeter at forward angles. To ensure the exclusivity of the process, a specially designed radial time projection chamber is used to detect the recoiling $^{4}\mathrm{He}$ nuclei. We measure beam-spin asymmetries larger than those observed on the free proton in the same kinematic domain. From these, we are able to extract, in a model-independent way, the real and imaginary parts of the only $^{4}\mathrm{He}$ Compton form factor, ${\mathcal{H}}_{A}$. This first measurement of coherent deeply virtual Compton scattering on the $^{4}\mathrm{He}$ nucleus, with a fully exclusive final state via nuclear recoil tagging, leads the way toward 3D imaging of the partonic structure of nuclei.
Published: 2017

50. Differential cross section measurements for γn→π−p above the first nucleon resonance region

Author: P. Eugenio, W. Kim, G. Niculescu, B. S. Ishkhanov, A. E. Kudryavtsev, A. Simonyan, Z. E. Meziani, V. P. Kubarovsky, S. M. Hughes, D. Adikaram, M. Guidal, X. Wei, K. Livingston, D. P. Watts, Michael Paolone, I. Bedlinskiy, H. Voskanyan, H. S. Jo, C. Salgado, A. Celentano, R. W. Gothe, R. A. Schumacher, Maxime Defurne, Dustin Keller, P. Lenisa, Jie Zhang, Michael Wood, K. Hafidi, P. Mattione, R. Fersch, G. D. Smith, M. Holtrop, G. Ciullo, J. P. Ball, Y. Prok, D. S. Carman, R. Paremuzyan, M. Osipenko, Alfred Švarc, Nicholas M. Harrison, Gerard Gilfoyle, Nikos Sparveris, I. I. Strakovsky, R. De Vita, S. V. Kuleshov, E. Voutier, K. P. Adhikari, D. Sokhan, S. Stepanyan, K. L. Giovanetti, N. Markov, A. Deur, D. G. Jenkins, A. Movsisyan, A. El Alaoui, Y. Ilieva, Nicholas Zachariou, Friedrich Klein, G. Rosner, N. K. Walford, T. Cao, S. Pisano, F. X. Girod, I. J. D. MacGregor, Laura Clark, Avraham Klein, P. L. Cole, Brian Raue, M. Bashkanov, S. Adhikari, B. McKinnon, S. Anefalos Pereira, S. Niccolai, M. Contalbrigo, O. Pogorelko, Z. W. Zhao, Victor Mokeev, A. I. Ostrovidov, A. Filippi, M. Ungaro, K. Park, I. Niculescu, J. W. Price, M. Taiuti, M. Ripani, D. Protopopescu, D. G. Ireland, V. Batourine, M. Khandaker, Z. Akbar, H. Jiang, E. De Sanctis, A. D'Angelo, Y. Ghandilyan, Volker D. Burkert, A. S. Biselli, O. Cortes, V. Crede, H. Hakobyan, K. Joo, L. El Fassi, Hovanes Egiyan, C. Munoz Camacho, E. L. Isupov, D. Heddle, E. Golovatch, G. Khachatryan, K. Hicks, R. A. Montgomery, P. Nadel-Turonski, Chaden Djalali, S. Boiarinov, Michael Dugger, T. Mineeva, G. Hollis, Taya Chetry, W. Phelps, W. J. Briscoe, Alessandro Rizzo, C. Hanretty, S. Procureur, A. Fradi, Ron L. Workman, S. Strauch, L. Lanza, Eugene Pasyuk, L. A. Net, N. A. Baltzell, R. Dupre, M. Battaglieri, K. A. Griffioen, Y. G. Sharabian, M. Khachatryan, G. Charles, J. A. Fleming, F. Sabatié, C. A. Meyer, G. V. Fedotov, Iu. Skorodumina, G. Murdoch, C. Gleason, Barry Ritchie, M. Hattawy, Sylvester Joosten, A. Kim, N. Dashyan, I. Stankovic, and V. E. Tarasov
Subjects: Physics, Particle physics, Photon, 010308 nuclear & particles physics, Bremsstrahlung, Resonance, State (functional analysis), 01 natural sciences, Particle identification, Pion, Amplitude, 0103 physical sciences, Atomic physics, 010306 general physics, Nucleon
Abstract: The quasifree $\ensuremath{\gamma}d\ensuremath{\rightarrow}{\ensuremath{\pi}}^{\ensuremath{-}}p(p)$ differential cross section has been measured with CLAS at photon beam energies ${E}_{\ensuremath{\gamma}}$ from 0.445 to 2.510 GeV (corresponding to $W$ from 1.311 to 2.366 GeV) for pion center-of-mass angles $cos{\ensuremath{\theta}}_{\ensuremath{\pi}}^{c.m.}$ from $\ensuremath{-}0.72$ to 0.92. A correction for final state interactions has been applied to these data to extract the $\ensuremath{\gamma}n\ensuremath{\rightarrow}{\ensuremath{\pi}}^{\ensuremath{-}}p$ differential cross sections. These cross sections are quoted in 8428 $({E}_{\ensuremath{\gamma}},cos{\ensuremath{\theta}}_{\ensuremath{\pi}}^{c.m.})$ bins, a factor of nearly 3 increase in the world statistics for this channel in this kinematic range. These new data help to constrain coupled-channel analysis fits used to disentangle the spectrum of ${N}^{*}$ resonances and extract their properties. Selected photon decay amplitudes ${N}^{*}\ensuremath{\rightarrow}\ensuremath{\gamma}n$ at the resonance poles are determined for the first time and are reported here.
Published: 2017

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