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1. Measurement of flavor asymmetry of the light-quark sea in the proton with Drell-Yan dimuon production in p+p and p+d collisions at 120 GeV

Author

Dove, J, Kerns, B, Leung, C, McClellan, RE, Miyasaka, S, Morton, DH, Nagai, K, Prasad, S, Sanftl, F, Scott, MBC, Tadepalli, AS, Aidala, CA, Arrington, J, Ayuso, C, Barker, CT, Brown, CN, Chang, TH, Chang, WC, Chen, A, Christian, DC, Dannowitz, BP, Daugherity, M, Diefenthaler, M, Fassi, L El, Geesaman, DF, Gilman, R, Goto, Y, Guo, L, Guo, R, Hague, TJ, Holt, RJ, Isenhower, D, Kinney, ER, Kitts, ND, Klein, A, Kleinjan, DW, Kudo, Y, Lin, P-J, Liu, K, Liu, MX, Lorenzon, W, Makins, NCR, de Medeiros, M Mesquita, McGaughey, PL, Miyachi, Y, Mooney, I, Nakahara, K, Nakano, K, Nara, S, Peng, JC, Puckett, AJ, Ramson, BJ, Reimer, PE, Rubin, JG, Sawada, S, Sawada, T, Shibata, T-A, Shiu, SH, Su, D, Teo, M, Tice, BG, Towell, RS, Uemura, S, Watson, TS, Wang, SG, Wickes, AB, Wu, J, Xi, Z, and Ye, Z

Subjects
Nuclear and Plasma Physics, Particle and High Energy Physics, Physical Sciences, Nuclear and plasma physics
Abstract

Evidence for a flavor asymmetry between the ū and d¯ quark distributions in the proton has been found in deep-inelastic scattering and Drell-Yan experiments. The pronounced dependence of this flavor asymmetry on x (fraction of nucleon momentum carried by partons) observed in the Fermilab E866 Drell-Yan experiment suggested a drop of the d¯(x)/ū(x) ratio in the x>0.15 region. We report results from the SeaQuest Fermilab E906 experiment with improved statistical precision for d¯(x)/ū(x) in the large x region up to x=0.45 using the 120 GeV proton beam. Two different methods for extracting the Drell-Yan cross section ratios, σpd/2σpp, from the SeaQuest data give consistent results. The d¯(x)/ū(x) ratios and the d¯(x)-ū(x) differences are deduced from these cross section ratios for 0.13

Published
2023

2. Publisher Correction: The asymmetry of antimatter in the proton.

Author

Dove, J, Kerns, B, McClellan, RE, Miyasaka, S, Morton, DH, Nagai, K, Prasad, S, Sanftl, F, Scott, MBC, Tadepalli, AS, Aidala, CA, Arrington, J, Ayuso, C, Barker, CL, Brown, CN, Chang, WC, Chen, A, Christian, DC, Dannowitz, BP, Daugherity, M, Diefenthaler, M, El Fassi, L, Geesaman, DF, Gilman, R, Goto, Y, Guo, L, Guo, R, Hague, TJ, Holt, RJ, Isenhower, D, Kinney, ER, Kitts, N, Klein, A, Kleinjan, DW, Kudo, Y, Leung, C, Lin, P-J, Liu, K, Liu, MX, Lorenzon, W, Makins, NCR, de Medeiros, M Mesquita, McGaughey, PL, Miyachi, Y, Mooney, I, Nakahara, K, Nakano, K, Nara, S, Peng, J-C, Puckett, AJ, Ramson, BJ, Reimer, PE, Rubin, JG, Sawada, S, Sawada, T, Shibata, T-A, Su, D, Teo, M, Tice, BG, Towell, RS, Uemura, S, Watson, S, Wang, SG, Wickes, AB, Wu, J, Xi, Z, and Ye, Z

Subjects
General Science & Technology
Abstract

In Fig. 1c of this Article, the x-axis scale was inadvertently duplicated from Fig. 1b. The original Article has been corrected online.

Published
2022

3. The asymmetry of antimatter in the proton

Author

Dove, J, Kerns, B, McClellan, RE, Miyasaka, S, Morton, DH, Nagai, K, Prasad, S, Sanftl, F, Scott, MBC, Tadepalli, AS, Aidala, CA, Arrington, J, Ayuso, C, Barker, CL, Brown, CN, Chang, WC, Chen, A, Christian, DC, Dannowitz, BP, Daugherity, M, Diefenthaler, M, El Fassi, L, Geesaman, DF, Gilman, R, Goto, Y, Guo, L, Guo, R, Hague, TJ, Holt, RJ, Isenhower, D, Kinney, ER, Kitts, N, Klein, A, Kleinjan, DW, Kudo, Y, Leung, C, Lin, P-J, Liu, K, Liu, MX, Lorenzon, W, Makins, NCR, de Medeiros, M Mesquita, McGaughey, PL, Miyachi, Y, Mooney, I, Nakahara, K, Nakano, K, Nara, S, Peng, J-C, Puckett, AJ, Ramson, BJ, Reimer, PE, Rubin, JG, Sawada, S, Sawada, T, Shibata, T-A, Su, D, Teo, M, Tice, BG, Towell, RS, Uemura, S, Watson, S, Wang, SG, Wickes, AB, Wu, J, Xi, Z, and Ye, Z

Subjects
Nuclear and Plasma Physics, Particle and High Energy Physics, Quantum Physics, Physical Sciences, General Science & Technology
Abstract

The fundamental building blocks of the proton-quarks and gluons-have been known for decades. However, we still have an incomplete theoretical and experimental understanding of how these particles and their dynamics give rise to the quantum bound state of the proton and its physical properties, such as its spin1. The two up quarks and the single down quark that comprise the proton in the simplest picture account only for a few per cent of the proton mass, the bulk of which is in the form of quark kinetic and potential energy and gluon energy from the strong force2. An essential feature of this force, as described by quantum chromodynamics, is its ability to create matter-antimatter quark pairs inside the proton that exist only for a very short time. Their fleeting existence makes the antimatter quarks within protons difficult to study, but their existence is discernible in reactions in which a matter-antimatter quark pair annihilates. In this picture of quark-antiquark creation by the strong force, the probability distributions as a function of momentum for the presence of up and down antimatter quarks should be nearly identical, given that their masses are very similar and small compared to the mass of the proton3. Here we provide evidence from muon pair production measurements that these distributions are considerably different, with more abundant down antimatter quarks than up antimatter quarks over a wide range of momenta. These results are expected to revive interest in several proposed mechanisms for the origin of this antimatter asymmetry in the proton that had been disfavoured by previous results4, and point to future measurements that can distinguish between these mechanisms.

Published
2021

4. Cross Sections for the Exclusive Photon Electroproduction on the Proton and Generalized Parton Distributions.

Author

Jo HS, Girod FX, Avakian H, Burkert VD, Garçon M, Guidal M, Kubarovsky V, Niccolai S, Stoler P, Adhikari KP, Adikaram D, Amaryan MJ, Anderson MD, Anefalos Pereira S, Ball J, Baltzell NA, Battaglieri M, Batourine V, Bedlinskiy I, Biselli AS, Boiarinov S, Briscoe WJ, Brooks WK, Carman DS, Celentano A, Chandavar S, Charles G, Colaneri L, Cole PL, Compton N, Contalbrigo M, Crede V, D'Angelo A, Dashyan N, De Vita R, De Sanctis E, Deur A, Djalali C, Dupre R, Alaoui AE, Fassi LE, Elouadrhiri L, Fedotov G, Fegan S, Filippi A, Fleming JA, Garillon B, Gevorgyan N, Ghandilyan Y, Gilfoyle GP, Giovanetti KL, Goetz JT, Golovatch E, Gothe RW, Griffioen KA, Guegan B, Guler N, Guo L, Hafidi K, Hakobyan H, Harrison N, Hattawy M, Hicks K, Hirlinger Saylor N, Ho D, Holtrop M, Hughes SM, Ilieva Y, Ireland DG, Ishkhanov BS, Jenkins D, Joo K, Joosten S, Keller D, Khachatryan G, Khandaker M, Kim A, Kim W, Klein A, Klein FJ, Kuhn SE, Kuleshov SV, Lenisa P, Livingston K, Lu HY, MacGregor IJ, McKinnon B, Meziani ZE, Mirazita M, Mokeev V, Montgomery RA, Moutarde H, Movsisyan A, Munevar E, Munoz Camacho C, Nadel-Turonski P, Net LA, Niculescu G, Osipenko M, Ostrovidov AI, Paolone M, Park K, Pasyuk E, Phillips JJ, Pisano S, Pogorelko O, Price JW, Procureur S, Prok Y, Puckett AJ, Raue BA, Ripani M, Rizzo A, Rosner G, Rossi P, Roy P, Sabatié F, Salgado C, Schott D, Schumacher RA, Seder E, Simonyan A, Skorodumina Iu, Smith GD, Sokhan D, Sparveris N, Stepanyan S, Strakovsky II, Strauch S, Sytnik V, Tian Y, Tkachenko S, Ungaro M, Voskanyan H, Voutier E, Walford NK, Watts DP, Wei X, Weinstein LB, Wood MH, Zachariou N, Zana L, Zhang J, Zhao ZW, and Zonta I

Abstract

Unpolarized and beam-polarized fourfold cross sections (d^{4}σ/dQ^{2}dx_{B}dtdϕ) for the ep→e^{'}p^{'}γ reaction were measured using the CLAS detector and the 5.75-GeV polarized electron beam of the Jefferson Lab accelerator, for 110 (Q^{2},x_{B},t) bins over the widest phase space ever explored in the valence-quark region. Several models of generalized parton distributions (GPDs) describe the data well at most of our kinematics. This increases our confidence that we understand the GPD H, expected to be the dominant contributor to these observables. Through a leading-twist extraction of Compton form factors, these results support the model predictions of a larger nucleon size at lower quark-momentum fraction x_{B}.

Published
2015
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5. Measurement of the Target-Normal Single-Spin Asymmetry in Quasielastic Scattering from the Reaction (3)He(↑)(e,e').

Author

Zhang YW, Long E, Mihovilovič M, Jin G, Allada K, Anderson B, Annand JR, Averett T, Ayerbe-Gayoso C, Boeglin W, Bradshaw P, Camsonne A, Canan M, Cates GD, Chen C, Chen JP, Chudakov E, De Leo R, Deng X, Deur A, Dutta C, El Fassi L, Flay D, Frullani S, Garibaldi F, Gao H, Gilad S, Gilman R, Glamazdin O, Golge S, Gomez J, Hansen O, Higinbotham DW, Holmstrom T, Huang J, Ibrahim H, de Jager CW, Jensen E, Jiang X, St John J, Jones M, Kang H, Katich J, Khanal HP, King P, Korsch W, LeRose J, Lindgren R, Lu HJ, Luo W, Markowitz P, Meziane M, Michaels R, Moffit B, Monaghan P, Muangma N, Nanda S, Norum BE, Pan K, Parno D, Piasetzky E, Posik M, Punjabi V, Puckett AJ, Qian X, Qiang Y, Qiu X, Riordan S, Ron G, Saha A, Sawatzky B, Schiavilla R, Schoenrock B, Shabestari M, Shahinyan A, Širca S, Subedi R, Sulkosky V, Tobias WA, Tireman W, Urciuoli GM, Wang D, Wang K, Wang Y, Watson J, Wojtsekhowski B, Ye Z, Zhan X, Zhang Y, Zheng X, Zhao B, and Zhu L

Abstract

We report the first measurement of the target single-spin asymmetry, A(y), in quasielastic scattering from the inclusive reaction (3)He(↑)(e,e') on a (3)He gas target polarized normal to the lepton scattering plane. Assuming time-reversal invariance, this asymmetry is strictly zero for one-photon exchange. A nonzero A(y) can arise from the interference between the one- and two-photon exchange processes which is sensitive to the details of the substructure of the nucleon. An experiment recently completed at Jefferson Lab yielded asymmetries with high statistical precision at Q(2)=0.13, 0.46, and 0.97  GeV(2). These measurements demonstrate, for the first time, that the (3)He asymmetry is clearly nonzero and negative at the 4σ-9σ level. Using measured proton-to-(3)He cross-section ratios and the effective polarization approximation, neutron asymmetries of -(1-3)% were obtained. The neutron asymmetry at high Q(2) is related to moments of the generalized parton distributions (GPDs). Our measured neutron asymmetry at Q(2)=0.97  GeV(2) agrees well with a prediction based on two-photon exchange using a GPD model and thus provides a new, independent constraint on these distributions.

Published
2015
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6. Polarization Transfer in Wide-Angle Compton Scattering and Single-Pion Photoproduction from the Proton.

Author

Fanelli C, Cisbani E, Hamilton DJ, Salmé G, Wojtsekhowski B, Ahmidouch A, Annand JR, Baghdasaryan H, Beaufait J, Bosted P, Brash EJ, Butuceanu C, Carter P, Christy E, Chudakov E, Danagoulian S, Day D, Degtyarenko P, Ent R, Fenker H, Fowler M, Frlez E, Gaskell D, Gilman R, Horn T, Huber GM, de Jager CW, Jensen E, Jones MK, Kelleher A, Keppel C, Khandaker M, Kohl M, Kumbartzki G, Lassiter S, Li Y, Lindgren R, Lovelace H, Luo W, Mack D, Mamyan V, Margaziotis DJ, Markowitz P, Maxwell J, Mbianda G, Meekins D, Meziane M, Miller J, Mkrtchyan A, Mkrtchyan H, Mulholland J, Nelyubin V, Pentchev L, Perdrisat CF, Piasetzky E, Prok Y, Puckett AJ, Punjabi V, Shabestari M, Shahinyan A, Slifer K, Smith G, Solvignon P, Subedi R, Wesselmann FR, Wood S, Ye Z, and Zheng X

Abstract

Wide-angle exclusive Compton scattering and single-pion photoproduction from the proton have been investigated via measurement of the polarization transfer from a circularly polarized photon beam to the recoil proton. The wide-angle Compton scattering polarization transfer was analyzed at an incident photon energy of 3.7 GeV at a proton scattering angle of θ_{cm}^{p}=70°. The longitudinal transfer K_{LL}, measured to be 0.645±0.059±0.048, where the first error is statistical and the second is systematic, has the same sign as predicted for the reaction mechanism in which the photon interacts with a single quark carrying the spin of the proton. However, the observed value is ~3 times larger than predicted by the generalized-parton-distribution-based calculations, which indicates a significant unknown contribution to the scattering amplitude.

Published
2015
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7. Towards a resolution of the proton form factor problem: new electron and positron scattering data.

Author

Adikaram D, Rimal D, Weinstein LB, Raue B, Khetarpal P, Bennett RP, Arrington J, Brooks WK, Adhikari KP, Afanasev AV, Amaryan MJ, Anderson MD, Anefalos Pereira S, Avakian H, Ball J, Battaglieri M, Bedlinskiy I, Biselli AS, Bono J, Boiarinov S, Briscoe WJ, Burkert VD, Carman DS, Careccia S, Celentano A, Chandavar S, Charles G, Colaneri L, Cole PL, Contalbrigo M, Crede V, D'Angelo A, Dashyan N, De Vita R, De Sanctis E, Deur A, Djalali C, Dodge GE, Dupre R, Egiyan H, El Alaoui A, El Fassi L, Elouadrhiri L, Eugenio P, Fedotov G, Fegan S, Filippi A, Fleming JA, Fradi A, Garillon B, Gilfoyle GP, Giovanetti KL, Girod FX, Goetz JT, Gohn W, Golovatch E, Gothe RW, Griffioen KA, Guegan B, Guidal M, Guo L, Hafidi K, Hakobyan H, Hanretty C, Harrison N, Hattawy M, Hicks K, Holtrop M, Hughes SM, Hyde CE, Ilieva Y, Ireland DG, Ishkhanov BS, Jenkins D, Jiang H, Jo HS, Joo K, Joosten S, Kalantarians N, Keller D, Khandaker M, Kim A, Kim W, Klein A, Klein FJ, Koirala S, Kubarovsky V, Kuhn SE, Livingston K, Lu HY, MacGregor IJ, Markov N, Mattione P, Mayer M, McKinnon B, Mestayer MD, Meyer CA, Mirazita M, Mokeev V, Montgomery RA, Moody CI, Moutarde H, Movsisyan A, Camacho CM, Nadel-Turonski P, Niccolai S, Niculescu G, Osipenko M, Ostrovidov AI, Park K, Pasyuk E, Peña C, Pisano S, Pogorelko O, Price JW, Procureur S, Prok Y, Protopopescu D, Puckett AJ, Ripani M, Rizzo A, Rosner G, Rossi P, Roy P, Sabatié F, Salgado C, Schott D, Schumacher RA, Seder E, Sharabian YG, Simonyan A, Skorodumina I, Smith ES, Smith GD, Sober DI, Sokhan D, Sparveris N, Stepanyan S, Stoler P, Strauch S, Sytnik V, Taiuti M, Tian Y, Trivedi A, Ungaro M, Voskanyan H, Voutier E, Walford NK, Watts DP, Wei X, Wood MH, Zachariou N, Zana L, Zhang J, Zhao ZW, and Zonta I

Abstract

There is a significant discrepancy between the values of the proton electric form factor, G(E)(p), extracted using unpolarized and polarized electron scattering. Calculations predict that small two-photon exchange (TPE) contributions can significantly affect the extraction of G(E)(p) from the unpolarized electron-proton cross sections. We determined the TPE contribution by measuring the ratio of positron-proton to electron-proton elastic scattering cross sections using a simultaneous, tertiary electron-positron beam incident on a liquid hydrogen target and detecting the scattered particles in the Jefferson Lab CLAS detector. This novel technique allowed us to cover a wide range in virtual photon polarization (ϵ) and momentum transfer (Q(2)) simultaneously, as well as to cancel luminosity-related systematic errors. The cross section ratio increases with decreasing ϵ at Q(2)=1.45  GeV(2). This measurement is consistent with the size of the form factor discrepancy at Q(2)≈1.75  GeV(2) and with hadronic calculations including nucleon and Δ intermediate states, which have been shown to resolve the discrepancy up to 2-3  GeV(2).

Published
2015
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8. Longitudinal target-spin asymmetries for deeply virtual compton scattering.

Author

Seder E, Biselli A, Pisano S, Niccolai S, Smith GD, Joo K, Adhikari K, Amaryan MJ, Anderson MD, Anefalos Pereira S, Avakian H, Battaglieri M, Bedlinskiy I, Bono J, Boiarinov S, Bosted P, Briscoe W, Brock J, Brooks WK, Bültmann S, Burkert VD, Carman DS, Carlin C, Celentano A, Chandavar S, Charles G, Colaneri L, Cole PL, Contalbrigo M, Crabb D, Crede V, D'Angelo A, Dashyan N, De Vita R, De Sanctis E, Deur A, Djalali C, Doughty D, Dupre R, El Fassi L, Elouadrhiri L, Eugenio P, Fedotov G, Fegan S, Filippi A, Fleming JA, Fradi A, Garillon B, Garçon M, Gevorgyan N, Ghandilyan Y, Giovanetti KL, Girod FX, Goetz JT, Gohn W, Gothe RW, Griffioen KA, Guegan B, Guidal M, Guo L, Hafidi K, Hakobyan H, Hanretty C, Harrison N, Hattawy M, Hirlinger Saylor N, Holtrop M, Hughes SM, Ilieva Y, Ireland DG, Ishkhanov BS, Isupov EL, Jo HS, Joosten S, Keith CD, Keller D, Khachatryan G, Khandaker M, Kim A, Kim W, Klein A, Klein FJ, Koirala S, Kubarovsky V, Kuhn SE, Lenisa P, Livingston K, Lu HY, MacGregor IJ, Markov N, Mayer M, McKinnon B, Meekins DG, Mineeva T, Mirazita M, Mokeev V, Montgomery R, Moody CI, Moutarde H, Movsisyan A, Munoz Camacho C, Nadel-Turonski P, Niculescu I, Osipenko M, Ostrovidov AI, Paolone M, Pappalardo LL, Park K, Park S, Pasyuk E, Peng P, Phelps W, Pogorelko O, Price JW, Prok Y, Protopopescu D, Puckett AJ, Ripani M, Rizzo A, Rosner G, Rossi P, Roy P, Sabatié F, Salgado C, Schott D, Schumacher RA, Senderovich I, Simonyan A, Skorodumina I, Sokhan D, Sparveris N, Stepanyan S, Stoler P, Strakovsky II, Strauch S, Sytnik V, Taiuti M, Tang W, Tian Y, Ungaro M, Voskanyan H, Voutier E, Walford NK, Watts DP, Wei X, Weinstein LB, Wood MH, Zachariou N, Zana L, Zhang J, and Zonta I

Abstract

A measurement of the electroproduction of photons off protons in the deeply inelastic regime was performed at Jefferson Lab using a nearly 6 GeV electron beam, a longitudinally polarized proton target, and the CEBAF Large Acceptance Spectrometer. Target-spin asymmetries for ep→e^{'}p^{'}γ events, which arise from the interference of the deeply virtual Compton scattering and the Bethe-Heitler processes, were extracted over the widest kinematics in Q^{2}, x_{B}, t, and ϕ, for 166 four-dimensional bins. In the framework of generalized parton distributions, at leading twist the t dependence of these asymmetries provides insight into the spatial distribution of the axial charge of the proton, which appears to be concentrated in its center. These results also bring important and necessary constraints for the existing parametrizations of chiral-even generalized parton distributions.

Published
2015
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9. Measurement of double-polarization asymmetries in the quasielastic (3)He[→](e[→],e(')d) process.

Author

Mihovilovič M, Jin G, Long E, Zhang YW, Allada K, Anderson B, Annand JR, Averett T, Boeglin W, Bradshaw P, Camsonne A, Canan M, Cates GD, Chen C, Chen JP, Chudakov E, De Leo R, Deng X, Deltuva A, Deur A, Dutta C, El Fassi L, Flay D, Frullani S, Garibaldi F, Gao H, Gilad S, Gilman R, Glamazdin O, Golak J, Golge S, Gomez J, Hansen O, Higinbotham DW, Holmstrom T, Huang J, Ibrahim H, de Jager CW, Jensen E, Jiang X, Jones M, Kang H, Katich J, Khanal HP, Kievsky A, King P, Korsch W, LeRose J, Lindgren R, Lu HJ, Luo W, Marcucci LE, Markowitz P, Meziane M, Michaels R, Moffit B, Monaghan P, Muangma N, Nanda S, Norum BE, Pan K, Parno D, Piasetzky E, Posik M, Punjabi V, Puckett AJ, Qian X, Qiang Y, Qui X, Riordan S, Saha A, Sauer PU, Sawatzky B, Schiavilla R, Schoenrock B, Shabestari M, Shahinyan A, Širca S, Skibiński R, John JS, Subedi R, Sulkosky V, Tobias WA, Tireman W, Urciuoli GM, Viviani M, Wang D, Wang K, Wang Y, Watson J, Wojtsekhowski B, Witała H, Ye Z, Zhan X, Zhang Y, Zheng X, Zhao B, and Zhu L

Abstract

We present a precise measurement of double-polarization asymmetries in the ^{3}He[over →](e[over →],e^{'}d) reaction. This particular process is a uniquely sensitive probe of hadron dynamics in ^{3}He and the structure of the underlying electromagnetic currents. The measurements have been performed in and around quasielastic kinematics at Q^{2}=0.25(GeV/c)^{2} for missing momenta up to 270  MeV/c. The asymmetries are in fair agreement with the state-of-the-art calculations in terms of their functional dependencies on p_{m} and ω, but are systematically offset. Beyond the region of the quasielastic peak, the discrepancies become even more pronounced. Thus, our measurements have been able to reveal deficiencies in the most sophisticated calculations of the three-body nuclear system, and indicate that further refinement in the treatment of their two-and/or three-body dynamics is required.

Published
2014
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10. Nuclear physics. Momentum sharing in imbalanced Fermi systems.

Author

Hen O, Sargsian M, Weinstein LB, Piasetzky E, Hakobyan H, Higinbotham DW, Braverman M, Brooks WK, Gilad S, Adhikari KP, Arrington J, Asryan G, Avakian H, Ball J, Baltzell NA, Battaglieri M, Beck A, May-Tal Beck S, Bedlinskiy I, Bertozzi W, Biselli A, Burkert VD, Cao T, Carman DS, Celentano A, Chandavar S, Colaneri L, Cole PL, Crede V, D'Angelo A, De Vita R, Deur A, Djalali C, Doughty D, Dugger M, Dupre R, Egiyan H, El Alaoui A, El Fassi L, Elouadrhiri L, Fedotov G, Fegan S, Forest T, Garillon B, Garcon M, Gevorgyan N, Ghandilyan Y, Gilfoyle GP, Girod FX, Goetz JT, Gothe RW, Griffioen KA, Guidal M, Guo L, Hafidi K, Hanretty C, Hattawy M, Hicks K, Holtrop M, Hyde CE, Ilieva Y, Ireland DG, Ishkanov BI, Isupov EL, Jiang H, Jo HS, Joo K, Keller D, Khandaker M, Kim A, Kim W, Klein FJ, Koirala S, Korover I, Kuhn SE, Kubarovsky V, Lenisa P, Levine WI, Livingston K, Lowry M, Lu HY, MacGregor IJ, Markov N, Mayer M, McKinnon B, Mineeva T, Mokeev V, Movsisyan A, Munoz Camacho C, Mustapha B, Nadel-Turonski P, Niccolai S, Niculescu G, Niculescu I, Osipenko M, Pappalardo LL, Paremuzyan R, Park K, Pasyuk E, Phelps W, Pisano S, Pogorelko O, Price JW, Procureur S, Prok Y, Protopopescu D, Puckett AJ, Rimal D, Ripani M, Ritchie BG, Rizzo A, Rosner G, Roy P, Rossi P, Sabatié F, Schott D, Schumacher RA, Sharabian YG, Smith GD, Shneor R, Sokhan D, Stepanyan SS, Stepanyan S, Stoler P, Strauch S, Sytnik V, Taiuti M, Tkachenko S, Ungaro M, Vlassov AV, Voutier E, Walford NK, Wei X, Wood MH, Wood SA, Zachariou N, Zana L, Zhao ZW, Zheng X, and Zonta I

Abstract

The atomic nucleus is composed of two different kinds of fermions: protons and neutrons. If the protons and neutrons did not interact, the Pauli exclusion principle would force the majority of fermions (usually neutrons) to have a higher average momentum. Our high-energy electron-scattering measurements using (12)C, (27)Al, (56)Fe, and (208)Pb targets show that even in heavy, neutron-rich nuclei, short-range interactions between the fermions form correlated high-momentum neutron-proton pairs. Thus, in neutron-rich nuclei, protons have a greater probability than neutrons to have momentum greater than the Fermi momentum. This finding has implications ranging from nuclear few-body systems to neutron stars and may also be observable experimentally in two-spin-state, ultracold atomic gas systems., (Copyright © 2014, American Association for the Advancement of Science.)

Published
2014
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11. Strangeness suppression of qq creation observed in exclusive reactions.

Author

Mestayer MD, Park K, Adhikari KP, Aghasyan M, Pereira SA, Ball J, Battaglieri M, Batourine V, Bedlinskiy I, Biselli AS, Boiarinov S, Briscoe WJ, Brooks WK, Burkert VD, Carman DS, Celentano A, Chandavar S, Charles G, Colaneri L, Cole PL, Contalbrigo M, Cortes O, Crede V, D'Angelo A, Dashyan N, De Vita R, Deur A, Djalali C, Doughty D, Dupre R, El Alaoui A, El Fassi L, Elouadrhiri L, Eugenio P, Fedotov G, Fleming JA, Forest TA, Garillon B, Garçon M, Ghandilyan Y, Gilfoyle GP, Giovanetti KL, Girod FX, Goetz JT, Golovatch E, Gothe RW, Griffioen KA, Guegan B, Guidal M, Hakobyan H, Hanretty C, Hattawy M, Holtrop M, Hughes SM, Hyde CE, Ilieva Y, Ireland DG, Jiang H, Jo HS, Joo K, Keller D, Khandaker M, Kim A, Kim W, Koirala S, Kubarovsky V, Kuleshov SV, Lenisa P, Levine WI, Livingston K, Lu HY, MacGregor IJ, Mayer M, McKinnon B, Meyer CA, Mirazita M, Mokeev V, Montgomery RA, Moody CI, Moutarde H, Movsisyan A, Camacho CM, Nadel-Turonski P, Niccolai S, Niculescu G, Niculescu I, Osipenko M, Ostrovidov AI, Pappalardo LL, Paremuzyan R, Peng P, Phelps W, Pisano S, Pogorelko O, Pozdniakov S, Price JW, Protopopescu D, Puckett AJ, Raue BA, Rimal D, Ripani M, Rizzo A, Rosner G, Roy P, Sabatié F, Saini MS, Schott D, Schumacher RA, Simonyan A, Sokhan D, Strauch S, Sytnik V, Tang W, Tian Y, Ungaro M, Vernarsky B, Vlassov AV, Voskanyan H, Voutier E, Walford NK, Watts DP, Wei X, Weinstein LB, Wood MH, Zachariou N, Zhang J, Zhao ZW, and Zonta I

Abstract

We measured the ratios of electroproduction cross sections from a proton target for three exclusive meson-baryon final states: ΛK(+), pπ(0), and nπ(+), with the CLAS detector at Jefferson Lab. Using a simple model of quark hadronization, we extract qq creation probabilities for the first time in exclusive two-body production, in which only a single qq pair is created. We observe a sizable suppression of strange quark-antiquark pairs compared to nonstrange pairs, similar to that seen in high-energy production.

Published
2014
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12. Measurement of the target-normal single-spin asymmetry in deep-inelastic scattering from the reaction (3)He(↑)(e,e')X.

Author

Katich J, Qian X, Zhao YX, Allada K, Aniol K, Annand JR, Averett T, Benmokhtar F, Bertozzi W, Bradshaw PC, Bosted P, Camsonne A, Canan M, Cates GD, Chen C, Chen JP, Chen W, Chirapatpimol K, Chudakov E, Cisbani E, Cornejo JC, Cusanno F, Dalton MM, Deconinck W, de Jager CW, De Leo R, Deng X, Deur A, Ding H, Dolph PA, Dutta C, Dutta D, El Fassi L, Frullani S, Gao H, Garibaldi F, Gaskell D, Gilad S, Gilman R, Glamazdin O, Golge S, Guo L, Hamilton D, Hansen O, Higinbotham DW, Holmstrom T, Huang J, Huang M, Ibrahim HF, Iodice M, Jiang X, Jin G, Jones MK, Kelleher A, Kim W, Kolarkar A, Korsch W, LeRose JJ, Li X, Li Y, Lindgren R, Liyanage N, Long E, Lu HJ, Margaziotis DJ, Markowitz P, Marrone S, McNulty D, Meziani ZE, Michaels R, Moffit B, Muñoz Camacho C, Nanda S, Narayan A, Nelyubin V, Norum B, Oh Y, Osipenko M, Parno D, Peng JC, Phillips SK, Posik M, Puckett AJ, Qiang Y, Rakhman A, Ransome RD, Riordan S, Saha A, Sawatzky B, Schulte E, Shahinyan A, Shabestari MH, Širca S, Stepanyan S, Subedi R, Sulkosky V, Tang LG, Tobias A, Urciuoli GM, Vilardi I, Wang K, Wang Y, Wojtsekhowski B, Yan X, Yao H, Ye Y, Ye Z, Yuan L, Zhan X, Zhang Y, Zhang YW, Zhao B, Zheng X, Zhu L, Zhu X, and Zong X

Abstract

We report the first measurement of the target-normal single-spin asymmetry in deep-inelastic scattering from the inclusive reaction 3)He(↑)(e,e')X on a polarized (3)He gas target. Assuming time-reversal invariance, this asymmetry is strictly zero in the Born approximation but can be nonzero if two-photon-exchange contributions are included. The experiment, conducted at Jefferson Lab using a 5.89 GeV electron beam, covers a range of 1.72  GeV, which is nonzero at the 2.89σ level. Our measured asymmetry agrees both in sign and magnitude with a two-photon-exchange model prediction that uses input from the Sivers transverse momentum distribution obtained from semi-inclusive deep-inelastic scattering.

Published
2014
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13. Hard two-body photodisintegration of 3He.

Author

Pomerantz I, Ilieva Y, Gilman R, Higinbotham DW, Piasetzky E, Strauch S, Adhikari KP, Aghasyan M, Allada K, Amaryan MJ, Anefalos Pereira S, Anghinolfi M, Baghdasaryan H, Ball J, Baltzell NA, Battaglieri M, Batourine V, Beck A, Beck S, Bedlinskiy I, Berman BL, Biselli AS, Boeglin W, Bono J, Bookwalter C, Boiarinov S, Briscoe WJ, Brooks WK, Bubis N, Burkert V, Camsonne A, Canan M, Carman DS, Celentano A, Chandavar S, Charles G, Chirapatpimol K, Cisbani E, Cole PL, Contalbrigo M, Crede V, Cusanno F, D'Angelo A, Daniel A, Dashyan N, de Jager CW, De Vita R, De Sanctis E, Deur A, Djalali C, Dodge GE, Doughty D, Dupre R, Dutta C, Egiyan H, El Alaoui A, El Fassi L, Eugenio P, Fedotov G, Fegan S, Fleming JA, Fradi A, Garibaldi F, Geagla O, Gevorgyan N, Giovanetti KL, Girod FX, Glister J, Goetz JT, Gohn W, Golovatch E, Gothe RW, Griffioen KA, Guegan B, Guidal M, Guo L, Hafidi K, Hakobyan H, Harrison N, Heddle D, Hicks K, Ho D, Holtrop M, Hyde CE, Ireland DG, Ishkhanov BS, Isupov EL, Jiang X, Jo HS, Joo K, Katramatou AT, Keller D, Khandaker M, Khetarpal P, Khrosinkova E, Kim A, Kim W, Klein FJ, Koirala S, Kubarovsky A, Kubarovsky V, Kuleshov SV, Kvaltine ND, Lee B, LeRose JJ, Lewis S, Lindgren R, Livingston K, Lu HY, MacGregor IJ, Mao Y, Martinez D, Mayer M, McCullough E, McKinnon B, Meekins D, Meyer CA, Michaels R, Mineeva T, Mirazita M, Moffit B, Mokeev V, Montgomery RA, Moutarde H, Munevar E, Munoz Camacho C, Nadel-Turonski P, Nasseripour R, Nepali CS, Niccolai S, Niculescu G, Niculescu I, Osipenko M, Ostrovidov AI, Pappalardo LL, Paremuzyan R, Park K, Park S, Petratos GG, Phelps E, Pisano S, Pogorelko O, Pozdniakov S, Procureur S, Protopopescu D, Puckett AJ, Qian X, Qiang Y, Ricco G, Rimal D, Ripani M, Ritchie BG, Rodriguez I, Ron G, Rosner G, Rossi P, Sabatié F, Saha A, Saini MS, Sarty AJ, Sawatzky B, Saylor NA, Schott D, Schulte E, Schumacher RA, Seder E, Seraydaryan H, Shneor R, Smith GD, Sokhan D, Sparveris N, Stepanyan SS, Stepanyan S, Stoler P, Subedi R, Sulkosky V, Taiuti M, Tang W, Taylor CE, Tkachenko S, Ungaro M, Vernarsky B, Vineyard MF, Voskanyan H, Voutier E, Walford NK, Wang Y, Watts DP, Weinstein LB, Weygand DP, Wojtsekhowski B, Wood MH, Yan X, Yao H, Zachariou N, Zhan X, Zhang J, Zhao ZW, Zheng X, and Zonta I

Abstract

We have measured cross sections for the γ(3)He → pd reaction at photon energies of 0.4-1.4 GeV and a center-of-mass angle of 90°. We observe dimensional scaling above 0.7 GeV at this center-of-mass angle. This is the first observation of dimensional scaling in the photodisintegration of a nucleus heavier than the deuteron.

Published
2013
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14. Measurement of exclusive π(0) electroproduction structure functions and their relationship to transverse generalized parton distributions.

Author

Bedlinskiy I, Kubarovsky V, Niccolai S, Stoler P, Adhikari KP, Aghasyan M, Amaryan MJ, Anghinolfi M, Avakian H, Baghdasaryan H, Ball J, Baltzell NA, Battaglieri M, Bennett RP, Biselli AS, Bookwalter C, Boiarinov S, Briscoe WJ, Brooks WK, Burkert VD, Carman DS, Celentano A, Chandavar S, Charles G, Contalbrigo M, Crede V, D'Angelo A, Daniel A, Dashyan N, De Vita R, De Sanctis E, Deur A, Djalali C, Doughty D, Dupre R, Egiyan H, El Alaoui A, El Fassi L, Elouadrhiri L, Eugenio P, Fedotov G, Fegan S, Fleming JA, Forest TA, Fradi A, Garçon M, Gevorgyan N, Giovanetti KL, Girod FX, Gohn W, Gothe RW, Graham L, Griffioen KA, Guegan B, Guidal M, Guo L, Hafidi K, Hakobyan H, Hanretty C, Heddle D, Hicks K, Holtrop M, Ilieva Y, Ireland DG, Ishkhanov BS, Isupov EL, Jo HS, Joo K, Keller D, Khandaker M, Khetarpal P, Kim A, Kim W, Klein FJ, Koirala S, Kubarovsky A, Kuhn SE, Kuleshov SV, Kvaltine ND, Livingston K, Lu HY, MacGregor IJ, Mao Y, Markov N, Martinez D, Mayer M, McKinnon B, Meyer CA, Mineeva T, Mirazita M, Mokeev V, Moutarde H, Munevar E, Munoz Camacho C, Nadel-Turonski P, Niculescu G, Niculescu I, Osipenko M, Ostrovidov AI, Pappalardo LL, Paremuzyan R, Park K, Park S, Pasyuk E, Anefalos Pereira S, Phelps E, Pisano S, Pogorelko O, Pozdniakov S, Price JW, Procureur S, Prok Y, Protopopescu D, Puckett AJ, Raue BA, Ricco G, Rimal D, Ripani M, Rosner G, Rossi P, Sabatié F, Saini MS, Salgado C, Saylor N, Schott D, Schumacher RA, Seder E, Seraydaryan H, Sharabian YG, Smith GD, Sober DI, Sokhan D, Stepanyan SS, Stepanyan S, Strauch S, Taiuti M, Tang W, Taylor CE, Tian Y, Tkachenko S, Ungaro M, Vineyard MF, Vlassov A, Voskanyan H, Voutier E, Walford NK, Watts DP, Weinstein LB, Weygand DP, Wood MH, Zachariou N, Zhang J, Zhao ZW, and Zonta I

Abstract

Exclusive π(0) electroproduction at a beam energy of 5.75 GeV has been measured with the Jefferson Lab CLAS spectrometer. Differential cross sections were measured at more than 1800 kinematic values in Q(2), x(B), t, and ϕ(π), in the Q(2) range from 1.0 to 4.6  GeV(2), -t up to 2  GeV(2), and x(B) from 0.1 to 0.58. Structure functions σ(T)+ϵσ(L), σ(TT), and σ(LT) were extracted as functions of t for each of 17 combinations of Q(2) and x(B). The data were compared directly with two handbag-based calculations including both longitudinal and transversity generalized parton distributions (GPDs). Inclusion of only longitudinal GPDs very strongly underestimates σ(T)+ϵσ(L) and fails to account for σ(TT) and σ(LT), while inclusion of transversity GPDs brings the calculations into substantially better agreement with the data. There is very strong sensitivity to the relative contributions of nucleon helicity-flip and helicity nonflip processes. The results confirm that exclusive π(0) electroproduction offers direct experimental access to the transversity GPDs.

Published
2012
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15. Polarization components in π0 photoproduction at photon energies up to 5.6 GeV.

Author

Luo W, Brash EJ, Gilman R, Jones MK, Meziane M, Pentchev L, Perdrisat CF, Puckett AJ, Punjabi V, Wesselmann FR, Ahmidouch A, Albayrak I, Aniol KA, Arrington J, Asaturyan A, Ates O, Baghdasaryan H, Benmokhtar F, Bertozzi W, Bimbot L, Bosted P, Boeglin W, Butuceanu C, Carter P, Chernenko S, Christy ME, Commisso M, Cornejo JC, Covrig S, Danagoulian S, Daniel A, Davidenko A, Day D, Dhamija S, Dutta D, Ent R, Frullani S, Fenker H, Frlez E, Garibaldi F, Gaskell D, Gilad S, Goncharenko Y, Hafidi K, Hamilton D, Higinbotham DW, Hinton W, Horn T, Hu B, Huang J, Huber GM, Jensen E, Kang H, Keppel C, Khandaker M, King P, Kirillov D, Kohl M, Kravtsov V, Kumbartzki G, Li Y, Mamyan V, Margaziotis DJ, Markowitz P, Marsh A, Matulenko Y, Maxwell J, Mbianda G, Meekins D, Melnik Y, Miller J, Mkrtchyan A, Mkrtchyan H, Moffit B, Moreno O, Mulholland J, Narayan A, Nuruzzaman, Nedev S, Piasetzky E, Pierce W, Piskunov NM, Prok Y, Ransome RD, Razin DS, Reimer PE, Reinhold J, Rondon O, Shabestari M, Shahinyan A, Shestermanov K, Širca S, Sitnik I, Smykov L, Smith G, Solovyev L, Solvignon P, Strakovsky II, Subedi R, Suleiman R, Tomasi-Gustafsson E, Vasiliev A, Veilleux M, Wood S, Ye Z, Zanevsky Y, Zhang X, Zhang Y, Zheng X, and Zhu L

Abstract

We present new data for the polarization observables of the final state proton in the (1)H(γ,p)π(0) reaction. These data can be used to test predictions based on hadron helicity conservation and perturbative QCD. These data have both small statistical and systematic uncertainties and were obtained with beam energies between 1.8 and 5.6 GeV and for π(0) scattering angles larger than 75° in the center-of-mass frame. The data extend the polarization measurements database for neutral pion photoproduction up to E(γ)=5.6 GeV. The results show a nonzero induced polarization above the resonance region. The polarization transfer components vary rapidly with the photon energy and π(0) scattering angle in the center-of-mass frame. This indicates that hadron helicity conservation does not hold and that the perturbative QCD limit is still not reached in the energy regime of this experiment.

Published
2012
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16. Measurement of the neutron radius of 208Pb through parity violation in electron scattering.

Author

Abrahamyan S, Ahmed Z, Albataineh H, Aniol K, Armstrong DS, Armstrong W, Averett T, Babineau B, Barbieri A, Bellini V, Beminiwattha R, Benesch J, Benmokhtar F, Bielarski T, Boeglin W, Camsonne A, Canan M, Carter P, Cates GD, Chen C, Chen JP, Hen O, Cusanno F, Dalton MM, De Leo R, de Jager K, Deconinck W, Decowski P, Deng X, Deur A, Dutta D, Etile A, Flay D, Franklin GB, Friend M, Frullani S, Fuchey E, Garibaldi F, Gasser E, Gilman R, Giusa A, Glamazdin A, Gomez J, Grames J, Gu C, Hansen O, Hansknecht J, Higinbotham DW, Holmes RS, Holmstrom T, Horowitz CJ, Hoskins J, Huang J, Hyde CE, Itard F, Jen CM, Jensen E, Jin G, Johnston S, Kelleher A, Kliakhandler K, King PM, Kowalski S, Kumar KS, Leacock J, Leckey J 4th, Lee JH, LeRose JJ, Lindgren R, Liyanage N, Lubinsky N, Mammei J, Mammoliti F, Margaziotis DJ, Markowitz P, McCreary A, McNulty D, Mercado L, Meziani ZE, Michaels RW, Mihovilovic M, Muangma N, Muñoz-Camacho C, Nanda S, Nelyubin V, Nuruzzaman N, Oh Y, Palmer A, Parno D, Paschke KD, Phillips SK, Poelker B, Pomatsalyuk R, Posik M, Puckett AJ, Quinn B, Rakhman A, Reimer PE, Riordan S, Rogan P, Ron G, Russo G, Saenboonruang K, Saha A, Sawatzky B, Shahinyan A, Silwal R, Sirca S, Slifer K, Solvignon P, Souder PA, Sperduto ML, Subedi R, Suleiman R, Sulkosky V, Sutera CM, Tobias WA, Troth W, Urciuoli GM, Waidyawansa B, Wang D, Wexler J, Wilson R, Wojtsekhowski B, Yan X, Yao H, Ye Y, Ye Z, Yim V, Zana L, Zhan X, Zhang J, Zhang Y, Zheng X, and Zhu P

Abstract

We report the first measurement of the parity-violating asymmetry A(PV) in the elastic scattering of polarized electrons from 208Pb. A(PV) is sensitive to the radius of the neutron distribution (R(n)). The result A(PV)=0.656±0.060(stat)±0.014(syst) ppm corresponds to a difference between the radii of the neutron and proton distributions R(n)-R(p)=0.33(-0.18)(+0.16) fm and provides the first electroweak observation of the neutron skin which is expected in a heavy, neutron-rich nucleus.

Published
2012
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17. Beam-target double-spin asymmetry A{LT} in charged pion production from deep inelastic scattering on a transversely polarized {3}He target at 1.4<Q{2}<2.7  GeV{2}.

Author

Huang J, Allada K, Dutta C, Katich J, Qian X, Wang Y, Zhang Y, Aniol K, Annand JR, Averett T, Benmokhtar F, Bertozzi W, Bradshaw PC, Bosted P, Camsonne A, Canan M, Cates GD, Chen C, Chen JP, Chen W, Chirapatpimol K, Chudakov E, Cisbani E, Cornejo JC, Cusanno F, Dalton MM, Deconinck W, de Jager CW, De Leo R, Deng X, Deur A, Ding H, Dolph PA, Dutta D, El Fassi L, Frullani S, Gao H, Garibaldi F, Gaskell D, Gilad S, Gilman R, Glamazdin O, Golge S, Guo L, Hamilton D, Hansen O, Higinbotham DW, Holmstrom T, Huang M, Ibrahim HF, Iodice M, Jiang X, Jin G, Jones MK, Kelleher A, Kim W, Kolarkar A, Korsch W, Lerose JJ, Li X, Li Y, Lindgren R, Liyanage N, Long E, Lu HJ, Margaziotis DJ, Markowitz P, Marrone S, McNulty D, Meziani ZE, Michaels R, Moffit B, Muñoz Camacho C, Nanda S, Narayan A, Nelyubin V, Norum B, Oh Y, Osipenko M, Parno D, Peng JC, Phillips SK, Posik M, Puckett AJ, Qiang Y, Rakhman A, Ransome RD, Riordan S, Saha A, Sawatzky B, Schulte E, Shahinyan A, Shabestari MH, Sirca S, Stepanyan S, Subedi R, Sulkosky V, Tang LG, Tobias A, Urciuoli GM, Vilardi I, Wang K, Wojtsekhowski B, Yan X, Yao H, Ye Y, Ye Z, Yuan L, Zhan X, Zhang YW, Zhao B, Zheng X, Zhu L, Zhu X, and Zong X

Abstract

We report the first measurement of the double-spin asymmetry A{LT} for charged pion electroproduction in semi-inclusive deep-inelastic electron scattering on a transversely polarized {3}He target. The kinematics focused on the valence quark region, 0.16

Published
2012
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18. Single spin asymmetries in charged pion production from semi-inclusive deep inelastic scattering on a transversely polarized 3He Target at Q2 = 1.4-2.7 GeV2.

Author

Qian X, Allada K, Dutta C, Huang J, Katich J, Wang Y, Zhang Y, Aniol K, Annand JR, Averett T, Benmokhtar F, Bertozzi W, Bradshaw PC, Bosted P, Camsonne A, Canan M, Cates GD, Chen C, Chen JP, Chen W, Chirapatpimol K, Chudakov E, Cisbani E, Cornejo JC, Cusanno F, Dalton MM, Deconinck W, de Jager CW, De Leo R, Deng X, Deur A, Ding H, Dolph PA, Dutta D, El Fassi L, Frullani S, Gao H, Garibaldi F, Gaskell D, Gilad S, Gilman R, Glamazdin O, Golge S, Guo L, Hamilton D, Hansen O, Higinbotham DW, Holmstrom T, Huang M, Ibrahim HF, Iodice M, Jiang X, Jin G, Jones MK, Kelleher A, Kim W, Kolarkar A, Korsch W, LeRose JJ, Li X, Li Y, Lindgren R, Liyanage N, Long E, Lu HJ, Margaziotis DJ, Markowitz P, Marrone S, McNulty D, Meziani ZE, Michaels R, Moffit B, Camacho CM, Nanda S, Narayan A, Nelyubin V, Norum B, Oh Y, Osipenko M, Parno D, Peng JC, Phillips SK, Posik M, Puckett AJ, Qiang Y, Rakhman A, Ransome RD, Riordan S, Saha A, Sawatzky B, Schulte E, Shahinyan A, Shabestari MH, Sirca S, Stepanyan S, Subedi R, Sulkosky V, Tang LG, Tobias A, Urciuoli GM, Vilardi I, Wang K, Wojtsekhowski B, Yan X, Yao H, Ye Y, Ye Z, Yuan L, Zhan X, Zhang YW, Zhao B, Zheng X, Zhu L, Zhu X, and Zong X

Abstract

We report the first measurement of target single spin asymmetries in the semi-inclusive (3)He(e,e'π(±))X reaction on a transversely polarized target. The experiment, conducted at Jefferson Lab using a 5.9 GeV electron beam, covers a range of 0.16 < x < 0.35 with 1.4 < Q(2) < 2.7 GeV(2). The Collins and Sivers moments were extracted from the azimuthal angular dependence of the measured asymmetries. The π(±) Collins moments for (3)He are consistent with zero, except for the π(+) moment at x = 0.35, which deviates from zero by 2.3σ. While the π(-) Sivers moments are consistent with zero, the π(+) Sivers moments favor negative values. The neutron results were extracted using the nucleon effective polarization and measured cross section ratios of proton to (3)He, and are largely consistent with the predictions of phenomenological fits and quark model calculations.

Published
2011
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19. Search for effects beyond the born approximation in polarization transfer observables in e(over→)p elastic scattering.

Author

Meziane M, Brash EJ, Gilman R, Jones MK, Luo W, Pentchev L, Perdrisat CF, Puckett AJ, Punjabi V, Wesselmann FR, Ahmidouch A, Albayrak I, Aniol KA, Arrington J, Asaturyan A, Ates O, Baghdasaryan H, Benmokhtar F, Bertozzi W, Bimbot L, Bosted P, Boeglin W, Butuceanu C, Carter P, Chernenko S, Christy E, Commisso M, Cornejo JC, Covrig S, Danagoulian S, Daniel A, Davidenko A, Day D, Dhamija S, Dutta D, Ent R, Frullani S, Fenker H, Frlez E, Garibaldi F, Gaskell D, Gilad S, Goncharenko Y, Hafidi K, Hamilton D, Higinbotham DW, Hinton W, Horn T, Hu B, Huang J, Huber GM, Jensen E, Kang H, Keppel C, Khandaker M, King P, Kirillov D, Kohl M, Kravtsov V, Kumbartzki G, Li Y, Mamyan V, Margaziotis DJ, Markowitz P, Marsh A, Matulenko Y, Maxwell J, Mbianda G, Meekins D, Melnik Y, Miller J, Mkrtchyan A, Mkrtchyan H, Moffit B, Moreno O, Mulholland J, Narayan A, Nuruzzaman, Nedev S, Piasetzky E, Pierce W, Piskunov NM, Prok Y, Ransome RD, Razin DS, Reimer PE, Reinhold J, Rondon O, Shabestari M, Shahinyan A, Shestermanov K, Širca S, Sitnik I, Smykov L, Smith G, Solovyev L, Solvignon P, Subedi R, Suleiman R, Tomasi-Gustafsson E, Vasiliev A, Vanderhaeghen M, Veilleux M, Wojtsekhowski BB, Wood S, Ye Z, Zanevsky Y, Zhang X, Zhang Y, Zheng X, and Zhu L

Abstract

Intensive theoretical and experimental efforts over the past decade have aimed at explaining the discrepancy between data for the proton electric to magnetic form factor ratio, G(E)/G(M), obtained separately from cross section and polarization transfer measurements. One possible explanation for this difference is a two-photon-exchange contribution. In an effort to search for effects beyond the one-photon-exchange or Born approximation, we report measurements of polarization transfer observables in the elastic H(e[over →],e(')p[over →]) reaction for three different beam energies at a Q(2)=2.5  GeV(2), spanning a wide range of the kinematic parameter ε. The ratio R, which equals μ(p)G(E)/G(M) in the Born approximation, is found to be independent of ε at the 1.5% level. The ε dependence of the longitudinal polarization transfer component P(ℓ) shows an enhancement of (2.3±0.6)% relative to the Born approximation at large ε., (© 2011 American Physical Society)

Published
2011
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20. Precise extraction of the induced polarization in the 4He(e,e'p)3H reaction.

Author

Malace SP, Paolone M, Strauch S, Albayrak I, Arrington J, Berman BL, Brash EJ, Briscoe B, Camsonne A, Chen JP, Christy ME, Chudakov E, Cisbani E, Craver B, Cusanno F, Ent R, Garibaldi F, Gilman R, Glamazdin O, Glister J, Higinbotham DW, Hyde-Wright CE, Ilieva Y, de Jager CW, Jiang X, Jones MK, Keppel CE, Khrosinkova E, Kuchina E, Kumbartzki G, Lee B, Lindgren R, Margaziotis DJ, Meekins D, Michaels R, Park K, Pentchev L, Perdrisat CF, Piasetzky E, Punjabi VA, Puckett AJ, Qian X, Qiang Y, Ransome RD, Saha A, Sarty AJ, Schulte E, Solvignon P, Subedi RR, Tang L, Tedeschi D, Tvaskis V, Udias JM, Ulmer PE, Vignote JR, Wesselmann FR, Wojtsekhowski B, and Zhan X

Abstract

We measured with unprecedented precision the induced polarization P(y) in (4)He(e,e'p)(3)H at Q(2)=0.8 and 1.3  (GeV/c)(2). The induced polarization is indicative of reaction-mechanism effects beyond the impulse approximation. Our results are in agreement with a relativistic distorted-wave impulse approximation calculation but are overestimated by a calculation with strong charge-exchange effects. Our data are used to constrain the strength of the spin-independent charge-exchange term in the latter calculation.

Published
2011
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21. Measurements of the electric form factor of the neutron up to Q2=3.4 GeV2 using the reaction 3He(e,e'n)pp.

Author

Riordan S, Abrahamyan S, Craver B, Kelleher A, Kolarkar A, Miller J, Cates GD, Liyanage N, Wojtsekhowski B, Acha A, Allada K, Anderson B, Aniol KA, Annand JR, Arrington J, Averett T, Beck A, Bellis M, Boeglin W, Breuer H, Calarco JR, Camsonne A, Chen JP, Chudakov E, Coman L, Crowe B, Cusanno F, Day D, Degtyarenko P, Dolph PA, Dutta C, Ferdi C, Fernández-Ramírez C, Feuerbach R, Fraile LM, Franklin G, Frullani S, Fuchs S, Garibaldi F, Gevorgyan N, Gilman R, Glamazdin A, Gomez J, Grimm K, Hansen JO, Herraiz JL, Higinbotham DW, Holmes R, Holmstrom T, Howell D, de Jager CW, Jiang X, Jones MK, Katich J, Kaufman LJ, Khandaker M, Kelly JJ, Kiselev D, Korsch W, LeRose J, Lindgren R, Markowitz P, Margaziotis DJ, Beck SM, Mayilyan S, McCormick K, Meziani ZE, Michaels R, Moffit B, Nanda S, Nelyubin V, Ngo T, Nikolenko DM, Norum B, Pentchev L, Perdrisat CF, Piasetzky E, Pomatsalyuk R, Protopopescu D, Puckett AJ, Punjabi VA, Qian X, Qiang Y, Quinn B, Rachek I, Ransome RD, Reimer PE, Reitz B, Roche J, Ron G, Rondon O, Rosner G, Saha A, Sargsian MM, Sawatzky B, Segal J, Shabestari M, Shahinyan A, Shestakov Y, Singh J, Sirca S, Souder P, Stepanyan S, Stibunov V, Sulkosky V, Tajima S, Tobias WA, Udias JM, Urciuoli GM, Vlahovic B, Voskanyan H, Wang K, Wesselmann FR, Vignote JR, Wood SA, Wright J, Yao H, and Zhu X

Abstract

The electric form factor of the neutron was determined from studies of the reaction 3He(e,e'n)pp in quasielastic kinematics in Hall A at Jefferson Lab. Longitudinally polarized electrons were scattered off a polarized target in which the nuclear polarization was oriented perpendicular to the momentum transfer. The scattered electrons were detected in a magnetic spectrometer in coincidence with neutrons that were registered in a large-solid-angle detector. More than doubling the Q2 range over which it is known, we find G(E)(n)=0.0236±0.0017(stat)±0.0026(syst), 0.0208±0.0024±0.0019, and 0.0147±0.0020±0.0014 for Q(2)=1.72, 2.48, and 3.41 GeV2, respectively.

Published
2010
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22. Polarization transfer in the 4He(e,e'p)3H reaction at Q2=0.8 and 1.3 (GeV/c)2.

Author

Paolone M, Malace SP, Strauch S, Albayrak I, Arrington J, Berman BL, Brash EJ, Briscoe B, Camsonne A, Chen JP, Christy ME, Chudakov E, Cisbani E, Craver B, Cusanno F, Ent R, Garibaldi F, Gilman R, Glamazdin O, Glister J, Higinbotham DW, Hyde-Wright CE, Ilieva Y, de Jager CW, Jiang X, Jones MK, Keppel CE, Khrosinkova E, Kuchina E, Kumbartzki G, Lee B, Lindgren R, Margaziotis DJ, Meekins D, Michaels R, Park K, Pentchev L, Perdrisat CF, Piasetzky E, Punjabi VA, Puckett AJ, Qian X, Qiang Y, Ransome RD, Saha A, Sarty AJ, Schulte E, Solvignon P, Subedi RR, Tang L, Tedeschi D, Tvaskis V, Udias JM, Ulmer PE, Vignote JR, Wesselmann FR, Wojtsekhowski B, and Zhan X

Abstract

Proton recoil polarization was measured in the quasielastic 4He(e,e'p)3H reaction at Q{2}=0.8 and 1.3  (GeV/c){2} with unprecedented precision. The polarization-transfer coefficients are found to differ from those of the 1H(e,e'p) reaction, contradicting a relativistic distorted-wave approximation and favoring either the inclusion of medium-modified proton form factors predicted by the quark-meson coupling model or a spin-dependent charge-exchange final-state interaction. For the first time, the polarization-transfer ratio is studied as a function of the virtuality of the proton.

Published
2010
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23. Recoil polarization measurements of the proton electromagnetic form factor ratio to Q2 = 8.5  GeV2.

Author

Puckett AJ, Brash EJ, Jones MK, Luo W, Meziane M, Pentchev L, Perdrisat CF, Punjabi V, Wesselmann FR, Ahmidouch A, Albayrak I, Aniol KA, Arrington J, Asaturyan A, Baghdasaryan H, Benmokhtar F, Bertozzi W, Bimbot L, Bosted P, Boeglin W, Butuceanu C, Carter P, Chernenko S, Christy E, Commisso M, Cornejo JC, Covrig S, Danagoulian S, Daniel A, Davidenko A, Day D, Dhamija S, Dutta D, Ent R, Frullani S, Fenker H, Frlez E, Garibaldi F, Gaskell D, Gilad S, Gilman R, Goncharenko Y, Hafidi K, Hamilton D, Higinbotham DW, Hinton W, Horn T, Hu B, Huang J, Huber GM, Jensen E, Keppel C, Khandaker M, King P, Kirillov D, Kohl M, Kravtsov V, Kumbartzki G, Li Y, Mamyan V, Margaziotis DJ, Marsh A, Matulenko Y, Maxwell J, Mbianda G, Meekins D, Melnik Y, Miller J, Mkrtchyan A, Mkrtchyan H, Moffit B, Moreno O, Mulholland J, Narayan A, Nedev S, Nuruzzaman, Piasetzky E, Pierce W, Piskunov NM, Prok Y, Ransome RD, Razin DS, Reimer P, Reinhold J, Rondon O, Shabestari M, Shahinyan A, Shestermanov K, Sirca S, Sitnik I, Smykov L, Smith G, Solovyev L, Solvignon P, Subedi R, Tomasi-Gustafsson E, Vasiliev A, Veilleux M, Wojtsekhowski BB, Wood S, Ye Z, Zanevsky Y, Zhang X, Zhang Y, Zheng X, and Zhu L

Abstract

Among the most fundamental observables of nucleon structure, electromagnetic form factors are a crucial benchmark for modern calculations describing the strong interaction dynamics of the nucleon's quark constituents; indeed, recent proton data have attracted intense theoretical interest. In this Letter, we report new measurements of the proton electromagnetic form factor ratio using the recoil polarization method, at momentum transfers Q2=5.2, 6.7, and 8.5  GeV2. By extending the range of Q2 for which G(E)(p) is accurately determined by more than 50%, these measurements will provide significant constraints on models of nucleon structure in the nonperturbative regime.

Published
2010
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