Author: "Adikaram D" / Publication Type: Reports - Searchworks@Jio Institute Digital Library Search Results

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1. Deeply virtual Compton scattering cross section at high Bjorken $x_B$

Author: Georges, F., Rashad, M. N. H., Stefanko, A., Dlamini, M., Karki, B., Ali, S. F., Lin, P-J., Ko, H-S, Israel, N., Adikaram, D., Ahmed, Z., Albataineh, H., Aljawrneh, B., Allada, K., Allison, S., Alsalmi, S., Androic, D., Aniol, K., Annand, J., Atac, H., Averett, T., Gayoso, C. Ayerbe, Bai, X., Bane, J., Barcus, S., Bartlett, K., Bellini, V., Beminiwattha, R., Bericic, J., Biswas, D., Brash, E., Bulumulla, D., Campbell, J., Camsonne, A., Carmignotto, M., Castellano, J., Chen, C., Chen, J-P., Chetry, T., Christy, M. E., Cisbani, E., Clary, B., Cohen, E., Compton, N., Cornejo, J. C., Dusa, S. Covrig, Crowe, B., Danagoulian, S., Danley, T., De Persio, F., Deconinck, W., Defurne, M., Desnault, C., Di, D., Duer, M., Duran, B., Ent, R., Fanelli, C., Franklin, G., Fuchey, E., Gal, C., Gaskell, D., Gautam, T., Glamazdin, O., Gnanvo, K., Gray, V. M., Gu, C., Hague, T., Hamad, G., Hamilton, D., Hamilton, K., Hansen, O., Hauenstein, F., Henry, W., Higinbotham, D. W., Holmstrom, T., Horn, T., Huang, Y., Huber, G. M., Hyde, C., Ibrahim, H., Jen, C-M., Jin, K., Jones, M., Kabir, A., Keppel, C., Khachatryan, V., King, P. M., Li, S., Li, W. B., Liu, J., Liu, H., Liyanage, A., Magee, J., Malace, S., Mammei, J., Markowitz, P., McClellan, E., Mazouz, M., Meddi, F., Meekins, D., Mesik, K., Michaels, R., Mkrtchyan, A., Montgomery, R., Camacho, C. Muñoz, Myers, L. S., Nadel-Turonski, P., Nazeer, S. J., Nelyubin, V., Nguyen, D., Nuruzzaman, N., Nycz, M., Obretch, O. F., Ou, L., Palatchi, C., Pandey, B., Park, S., Park, K., Peng, C., Pomatsalyuk, R., Pooser, E., Puckett, A. J. R., Punjabi, V., Quinn, B., Rahman, S., Reimer, P. E., Roche, J., Sapkota, I., Sarty, A., Sawatzky, B., Saylor, N. H., Schmookler, B., Shabestari, M. H., Shahinyan, A., Sirca, S., Smith, G. R., Sooriyaarachchilage, S., Sparveris, N., Spies, R., Su, T., Subedi, A., Sulkosky, V., Sun, A., Thorne, L., Tian, Y., Ton, N., Tortorici, F., Trotta, R., Urciuoli, G. M., Voutier, E., Waidyawansa, B., Wang, Y., Wojtsekhowski, B., Wood, S., Yan, X., Ye, L., Ye, Z., Yero, C., Zhang, J., Zhao, Y., and Zhu, P.
Subjects: High Energy Physics - Phenomenology, High Energy Physics - Experiment, Nuclear Experiment
Abstract: We report high-precision measurements of the Deeply Virtual Compton Scattering (DVCS) cross section at high values of the Bjorken variable $x_B$. DVCS is sensitive to the Generalized Parton Distributions of the nucleon, which provide a three-dimensional description of its internal constituents. Using the exact analytic expression of the DVCS cross section for all possible polarization states of the initial and final electron and nucleon, and final state photon, we present the first experimental extraction of all four helicity-conserving Compton Form Factors (CFFs) of the nucleon as a function of $x_B$, while systematically including helicity flip amplitudes. In particular, the high accuracy of the present data demonstrates sensitivity to some very poorly known CFFs.
Published: 2022
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2. Form Factors and Two-Photon Exchange in High-Energy Elastic Electron-Proton Scattering

Author: Christy, M. E., Gautam, T., Ou, L., Schmookler, B., Wang, Y., Adikaram, D., Ahmed, Z., Albataineh, H., Ali, S. F., Aljawrneh, B., Allada, K., Allison, S. L., Alsalmi, S., Androic, D., Aniol, K., Annand, J., Arrington, J., Atac, H., Averett, T., Gayoso, C. Ayerbe, Bai, X., Bane, J., Barcus, S., Bartlett, K., Bellini, V., Beminiwattha, R., Bericic, J., Bhatt, H., Bhetuwal, D., Biswas, D., Brash, E., Bulumulla, D., Camacho, C. M., Campbell, J., Camsonne, A., Carmignotto, M., Castellanos, J., Chen, C., Chen, J-P., Chetry, T., Cisbani, E., Clary, B., Cohen, E., Compton, N., Cornejo, J. C., Dusa, S. Covrig, Crowe, B., Danagoulian, S., Danley, T., Deconinck, W., Defurne, M., Desnault, C., Di, D., Dlamini, M., Duer, M., Duran, B., Ent, R., Fanelli, C., Fuchey, E., Gal, C., Gaskell, D., Georges, F., Gilad, S., Glamazdin, O., Gnanvo, K., Gramolin, A. V., Gray, V. M., Gu, C., Habarakada, A., Hague, T., Hamad, G., Hamilton, D., Hamilton, K., Hansen, O., Hauenstein, F., Hernandez, A. V., Henry, W., Higinbotham, D. W., Holmstrom, T., Horn, T., Huang, Y., Huber, G. M., Hyde, C., Ibrahim, H., Israel, N., Jen, C-M., Jin, K., Jones, M., Kabir, A., Karki, B., Keppel, C., Khachatryan, V., King, P. M., Li, S., Li, W., Liu, H., Liu, J., Liyanage, A. H., Mack, D., Magee, J., Malace, S., Mammei, J., Markowitz, P., Mayilyan, S., McClellan, E., Meddi, F., Meekins, D., Mesick, K., Michaels, R., Mkrtchyan, A., Moffit, B., Montgomery, R., Myers, L. S., Nadel-Turonski, P., Nazeer, S. J., Nelyubin, V., Nguyen, D., Nuruzzaman, N., Nycz, M., Obrecht, R. F., Ohanyan, K., Palatchi, C., Pandey, B., Park, K., Park, S., Peng, C., Persio, F. D., Pomatsalyuk, R., Pooser, E., Puckett, A. J. R., Punjabi, V., Quinn, B., Rahman, S., Rashad, M. N. H., Riordan, S., Roche, J., Sapkota, I., Sarty, A., Sawatzky, B., Saylor, N. H., Shabestari, M. H., Shahinyan, A., Sirca, S., Smith, G. R., Sooriyaarachchilage, S., Sparveris, N., Spies, R., Stefanko, A., Su, T., Subedi, A., Sulkosky, V., Sun, A., Tan, Y., Thorne, L., Ton, N., Tortorici, F., Trotta, R., Uniyal, R., Urciuoli, G. M., Voutier, E., Waidyawansa, B., Wojtsekhowski, B., Wood, S., Yan, X., Ye, L., Ye, Z. H., Yero, C., Zhang, J., Zhao, Y. X., and Zhu, P.
Subjects: Nuclear Experiment, High Energy Physics - Experiment
Abstract: We present new precision measurements of the elastic electron-proton scattering cross section for momentum transfer (Q$^2$) up to 15.75~\gevsq. Combined with existing data, these provide an improved extraction of the proton magnetic form factor at high Q$^2$ and double the range over which a longitudinal/transverse separation of the cross section can be performed. The difference between our results and polarization data agrees with that observed at lower Q$^2$ and attributed to hard two-photon exchange (TPE) effects, extending to 8~(GeV/c)$^2$ the range of Q$^2$ for which a discrepancy is established at $>$95\% confidence. We use the discrepancy to quantify the size of TPE contributions needed to explain the cross section at high Q$^2$., Comment: 7 pages, 2 figures
Published: 2021
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3. Deep exclusive electroproduction of $\pi^0$ at high $Q^2$ in the quark valence regime

Author: The Jefferson Lab Hall A Collaboration, Dlamini, M., Karki, B., Ali, S. F., Lin, P-J., Georges, F., Ko, H-S, Israel, N., Rashad, M. N. H., Stefanko, A., Adikaram, D., Ahmed, Z., Albataineh, H., Aljawrneh, B., Allada, K., Allison, S., Alsalmi, S., Androic, D., Aniol, K., Annand, J., Atac, H., Averett, T., Gayoso, C. Ayerbe, Bai, X., Bane, J., Barcus, S., Bartlett, K., Bellini, V., Beminiwattha, R., Bericic, J., Biswas, D., Brash, E., Bulumulla, D., Campbell, J., Camsonne, A., Carmignotto, M., Castellano, J., Chen, C., Chen, J-P., Chetry, T., Christy, M. E., Cisbani, E., Clary, B., Cohen, E., Compton, N., Cornejo, J. C., Dusa, S. Covrig, Crowe, B., Danagoulian, S., Danley, T., De Persio, F., Deconinck, W., Defurne, M., Desnault, C., Di, D., Duer, M., Duran, B., Ent, R., Fanelli, C., Franklin, G., Fuchey, E., Gal, C., Gaskell, D., Gautam, T., Glamazdin, O., Gnanvo, K., Gray, V. M., Gu, C., Hague, T., Hamad, G., Hamilton, D., Hamilton, K., Hansen, O., Hauenstein, F., Henry, W., Higinbotham, D. W., Holmstrom, T., Horn, T., Huang, Y., Huber, G. M., Hyde, C., Ibrahim, H., Jen, C-M., Jin, K., Jones, M., Kabir, A., Keppel, C., Khachatryan, V., King, P. M., Li, S., Li, W., Liu, J., Liu, H., Liyanage, A., Magee, J., Malace, S., Mammei, J., Markowitz, P., McClellan, E., Meddi, F., Meekins, D., Mesik, K., Michaels, R., Mkrtchyan, A., Montgomery, R., Camacho, C. Munoz, Myers, L. S., Nadel-Turonski, P., Nazeer, S. J., Nelyubin, V., Nguyen, D., Nuruzzaman, N., Nycz, M., Obretch, O. F., Ou, L., Palatchi, C., Pandey, B., Park, S., Park, K., Peng, C., Pomatsalyuk, R., Pooser, E., Puckett, A. J. R., Punjabi, V., Quinn, B., Rahman, S., Reimer, P. E., Roche, J., Sapkota, I., Sarty, A., Sawatzky, B., Saylor, N. H., Schmookler, B., Shabestari, M. H., Shahinyan, A., Sirca, S., Smith, G. R., Sooriyaarachchilage, S., Sparveris, N., Spies, R., Su, T., Subedi, A., Sulkosky, V., Sun, A., Thorne, L., Tian, Y., Ton, N., Tortorici, F., Trotta, R., Urciuoli, G. M., Voutier, E., Waidyawansa, B., Wang, Y., Wojtsekhowski, B., Wood, S., Yan, X., Ye, L., Ye, Z., Yero, C., Zhang, J., Zhao, Y., and Zhu, P.
Subjects: High Energy Physics - Experiment, Nuclear Experiment
Abstract: We report measurements of the exclusive neutral pion electroproduction cross section off protons at large values of $x_B$ (0.36, 0.48 and 0.60) and $Q^2$ (3.1 to 8.4 GeV$^2$) obtained from Jefferson Lab Hall A experiment E12-06-014. The corresponding structure functions $d\sigma_L/dt+\epsilon d\sigma_T/dt$, $d\sigma_{TT}/dt$, $d\sigma_{LT}/dt$ and $d\sigma_{LT'}/dt$ are extracted as a function of the proton momentum transfer $t-t_{min}$. The results suggest the amplitude for transversely polarized virtual photons continues to dominate the cross-section throughout this kinematic range. The data are well described by calculations based on transversity Generalized Parton Distributions coupled to a helicity flip Distribution Amplitude of the pion, thus providing a unique way to probe the structure of the nucleon.
Published: 2020
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4. Beam-Target Helicity Asymmetry $E$ in $K^{0}\Lambda$ and $K^{0}\Sigma^0$ Photoproduction on the Neutron

Author: CLAS Collaboration, Ho, D. H., Schumacher, R. A., D'Angelo, A., Deur, A., Fleming, J., Hanretty, C., Kageya, T., Klein, F. J., Klempt, E., Lowry, M. M., Lu, H., Nikonov, V. A., Peng, P., Sandorfi, A. M., Sarantsev, A. V., Strakovsky, I. I., Walford, N. K., Wei, X., Workman, R. L., Adhikari, K. P., Adhikari, S., Adikaram, D., Akbar, Z., Ball, J., Barion, L., Bashkanov, M., Bass, C. D., Battaglieri, M., Bedlinskiy, I., Biselli, A. S., Briscoe, W. J., Boiarinov, S., Burkert, V. D., Cao, F., Carman, D. S., Celentano, A., Chandavar, S., Charles, G., Chatagnon, P., Chetry, T., Ciullo, G., Clary, B. A., Cole, P., Contalbrigo, M., Crede, V., De Vita, R., Defurne, M., Diehl, S., Djalali, C., Dupre, R., Egiyan, H., Ehrhart, M., Alaoui, A. El, Fassi, L. El, Eugenio, P., Fedotov, G., Fegan, S., Fersch, R., Filippi, A., Fradi, A., Ghandilyan, Y., Giovanetti, K. L., Girod, F. X., Gohn, W., Golovatch, E., Gothe, R. W., Griffioen, K. A., Guidal, M., Hafidi, K., Hakobyan, H., Harrison, N., Hattawy, M., Heddle, D., Hicks, K., Holtrop, M., Ilieva, Y., Ireland, D. G., Ishkhanov, B. S., Isupov, E. L., Jenkins, D., Jo, H. S., Johnston, S., Kabir, M. L., Keller, D., Khachatryan, G., Khachatryan, M., Khandaker, M., Kim, A., Kim, W., Klein, A., Kubarovsky, V., Laine, V., Lanza, L., Lenisa, P., Livingston, K., MacGregor, I . J . D., Marchand, D., Markov, N., Mayer, M., McKinnon, B., Meyer, C. A., Mirazita, M., Mokeev, V., Montgomery, R. A., Movsisyan, A, Camacho, C. Munoz, Nadel-Turonski, P., Niccolai, S., Niculescu, G., O'Connell, T., Osipenko, M., Ostrovidov, A. I., Paolone, M., Paremuzyan, R., Park, K., Pasyuk, E., Pogorelko, O., Price, J. W., Prok, Y., Protopopescu, D., Rehfuss, M., Ripani, M., Riser, D., Rizzo, A., Rosner, G., Sabatié, F., Salgado, C., Sharabian, Y. G., Skorodumina, Iu., Smith, G. D., Sober, D. I., Sokhan, D., Sparveris, N., Strauch, S., Taiuti, M., Tan, J. A., Ungaro, M., Voskanyan, H., Voutier, E., Wang, R., Watts, D. P., Weinstein, L. B., Whisnant, C. S., Wood, M. H., Zachariou, N., Zhang, J., Zhao, Z. W., and Zonta, I.
Subjects: Nuclear Experiment
Abstract: We report the first measurements of the $E$ beam-target helicity asymmetry for the $\vec{\gamma} \vec{n} \to K^{0}\Lambda$, and $K^{0}\Sigma^{0}$ channels in the energy range 1.70$\leq W\leq$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 was 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 $I=1$ photo-coupling transition amplitudes in pseudoscalar meson photoproduction., Comment: 14 pages, 9 figures; Revised to match published version
Published: 2018
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5. Semi-Inclusive $\pi_0$ target and beam-target asymmetries from 6 GeV electron scattering with CLAS

Author: Jawalkar, S., Koirala, S., Avakian, H., Bosted, P., Griffioen, K. A., Keith, C., Kuhn, S. E., Adhikari, K. P., Adhikari, S., Adikaram, D., Akbar, Z., Amaryan, M. J., Pereira, S. Anefalos, Ball, J., Baltzell, N. A., Battaglieri, M., Batourine, V., Bedlinskiy, I., Biselli, A. S., Boiarinov, S., Briscoe, W. J., Brock, J., Brooks, W. K., Bultmann, S., Burkert, V. D., Cao, Frank Thanh, Carlin, C., Carman, D. S., Celentano, A., Charles, G., Chetry, T., Ciullo, G., Clark, L., Colaneri, L., Cole, P. L., Contalbrigo, M., Cortes, O., Crede, V., D'Angelo, A., Dashyan, N., De Vita, R., De Sanctis, E., Defurne, M., Deur, A., Djalali, C., Ddoge, G., Dupre, R., Egiyan, H., Alaoui, A. El, Fassi, L. El, Elouadrhiri, L., Eugenio, P., Fedotov, G., Fegan, S., Fersch, R., Filippi, A., Fleming, J. A., Forest, T. A., Fradi, A., Garcon, M., Ghandilyan, Y., Gilfoyle, G. P., Giovanetti, K. L., Girod, F. X., Gleason, C., Gohn, W., Golovatch, E., Gothe, R. W., Guidal, M., Guler, N., Guo, L., Hakobyan, H., Hanretty, C., Harrison, N., Hattawy, M., Heddle, D., Hicks, K., Hollis, G., Holtrop, M., Hughes, S. M., Ilieva, Y., Ireland, D. G., Ishkhanov, B. S., Isupov, E. L., Jenkins, D., Jiang, H., Joo, K., Joosten, S., Keller, D., Khachatryan, G., Khachatryan, M., Khandaker, M., Kim, A., Kim, W., Klein, A., Klein, F. J., Kubarovsky, V., Kuleshov, S. V., Lanza, L., Lenisa, P., Livingston, K., Lu, H. Y., MacGregor, I . J . D., Markov, N., Mayer, M., McCracken, M. E., McKinnon, B., Meyer, C. A., Mineeva, T., Mirazita, M., Mokeev, V., Montgomery, R. A., Movsisyan, A, Camacho, C. Munoz, Nadel-Turonski, P., Net, L. A., Niccolai, S., Niculescu, G., Niculescu, I., Osipenko, M., Ostrovidov, A. I., Paremuzyan, R., Park, K., Pasyuk, E., Phelps, E., Phelps, W., Pierce, J., Pisano, S., Pogorelko, O., Price, J. W., Prok, Y., Protopopescu, D., Raue, B. A., Ripani, M., Riser, D., Rizzo, A., Rosner, G., Rossi, P., Sabatie, F., Salgado, C., Schumacher, R. A., Seder, E., Sharabian, Y. G., Simonyan, A., Skorodumina, Iu., Smith, G. D., Sober, D. I., Sokhan, D., Sparveris, N., Stankovic, I., Strauch, S., Taiuti, M., Ungaro, M., Voskanyan, H., Voutier, E., Walford, N. K., Watts, D. P., Wei, X., Weinstein, L. B., Wood, M. H., Zachariou, N., Zhang, J., and Zhao, Z. W.
Subjects: Nuclear Experiment, High Energy Physics - Phenomenology
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
Published: 2017
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6. First Exclusive Measurement of Deeply Virtual Compton Scattering off $^4$He: Toward the 3D Tomography of Nuclei

Author: Hattawy, M., Baltzell, N. A., Dupré, R., Hafidi, K., Stepanyan, S., Bültmann, S., De Vita, R., Alaoui, A. El, Fassi, L. El, Egiyan, H., Girod, F. X., Guidal, M., Jenkins, D., Liuti, S., Perrin, Y., Torayev, B., Voutier, E., Adhikari, K. P., Adhikari, S., Adikaram, D., Akbar, Z., Amaryan, M. J., Pereira, S. Anefalos, Armstrong, Whitney R., Avakian, H., Ball, J., Bashkanov, M., Battaglieri, M., Batourine, V., Bedlinskiy, I., Biselli, A. S., Boiarinov, S., Briscoe, W. J., Brooks, W. K., Burkert, V. D., Cao, Frank Thanh, Carman, D. S., Celentano, A., Charles, G., Chetry, T., Ciullo, G., Clark, L., Colaneri, L., Cole, P. L., Contalbrigo, M., Cortes, O., Crede, V., D'Angelo, A., Dashyan, N., De Sanctis, E., Deur, A., Djalali, C., Elouadrhiri, L., Eugenio, P., Fedotov, G., Fegan, S., Fersch, R., Filippi, A., Fleming, J. A., Forest, T. A., Fradi, A., Garçon, M., Gevorgyan, N., Ghandilyan, Y., Gilfoyle, G. P., Giovanetti, K. L., Gleason, C., Gohn, W., Golovatch, E., Gothe, R. W., Griffioen, K. A., Guo, L., Hakobyan, H., Hanretty, C., Harrison, N., Heddle, D., Hicks, K., Holtrop, M., Hughes, S. M., Ireland, D. G., Ishkhanov, B. S., Isupov, E. L., Jiang, H., Joo, K., Joosten, S., Keller, D., Khachatryan, G., Khachatryan, M., Khandaker, M., Kim, A., Kim, W., Klein, A., Klein, F. J., Kubarovsky, V., Kuhn, S. E., Kuleshov, S. V., Lanza, L., Lenisa, P., Livingston, K., Lu, H. Y., MacGregor, I . J . D., Markov, N., Mayer, M., McCracken, M. E., McKinnon, B., Meyer, C. A., Meziani, Z. E., Mineeva, T., Mirazita, M., Mokeev, V., Montgomery, R. A., Moutarde, H., Movsisyan, A, Camacho, C. Munoz, Nadel-Turonski, P., Net, L. A., Niccolai, S., Niculescu, G., Niculescu, I., Osipenko, M., Ostrovidov, A. I., Paolone, M., Paremuzyan, R., Park, K., Pasyuk, E., Phelps, E., Phelps, W., Pisano, S., Pogorelko, O., Price, J. W., Prok, Y., Protopopescu, D., Ripani, M., Ritchie, B. G., Rizzo, A., Rosner, G., Rossi, P., Sabatié, F., Salgado, C., Schumacher, R. A., Seder, E., Sharabian, Y. G., Simonyan, A., Skorodumina, Iu., Smith, G. D., Sokhan, D., Sparveris, N., Strauch, S., Taiuti, M., Ungaro, M., Voskanyan, H., Walford, N. K., Watts, D. P., Wei, X., Weinstein, L. B., Wood, M. H., Zachariou, N., Zana, L., Zhang, J., and Zhao, Z. W.
Subjects: Nuclear Experiment, High Energy Physics - Experiment
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 used the 6 GeV electron beam from the CEBAF accelerator at Jefferson Lab incident on a pressurized $^4$He gaseous target placed in front of the CEBAF Large Acceptance Spectrometer (CLAS). The scattered electron was 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 was used to detect the recoiling $^4$He nuclei. We measured beam-spin asymmetries larger than those observed on the free proton in the same kinematic domain. From these, we were able to extract, in a model-independent way, the real and imaginary parts of the only $^4$He Compton form factor, $\cal H_A$. This first measurement of coherent deeply virtual Compton scattering on the $^4$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
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7. Photon beam asymmetry $\Sigma$ in the reaction $\vec{\gamma} p \to p \omega$ for $E_\gamma$ = 1.152 to 1.876 GeV

Author: CLAS Collaboration, Collins, P., Ritchie, B. G., Dugger, M., Klein, F. J., Anisovich, A. V., Klempt, E., Nikonov, V. A., Sarantsev, A., Adhikari, K. P., Adhikari, S., Adikaram, D., Akbar, Z., Pereira, S. Anefalos, Avakian, H., Ball, J., Baltzell, N. A., Bashkanov, M., Battaglieri, M., Batourine, V., Bedlinskiy, I., Biselli, A. S., Boiarinov, S., Briscoe, W. J., Brooks, W. K., Burkert, V. D., Cao, Frank Thanh, Cao, T., Carman, D. S., Celentano, A., Charles, G., Chetry, T., Ciullo, G., Clark, L., Cole, P. L., Contalbrigo, M., Cortes, O., Crede, V., Dashyan, N., De Vita, R., De Sanctis, E., Defurne, M., Deur, A., Djalali, C., Dupre, R., Egiyan, H., Alaoui, A. El, Fassi, L. El, Eugenio, P., Fedotov, G., Filippi, A., Fleming, J. A., Ghandilyan, Y., Gilfoyle, G. P., Giovanetti, K. L., Girod, F. X., Glazier, D. I., Gleason, C., Golovatch, E., Gothe, R. W., Griffioen, K. A., Guidal, M., Hafidi, K., Hakobyan, H., Hanretty, C., Harrison, N., Hattawy, M., Heddle, D., Hicks, K., Hollis, G., Holtrop, M., Hughes, S. M., Ilieva, Y., Ireland, D. G., Ishkhanov, B. S., Isupov, E. L., Jenkins, D., Jiang, H., Jo, H. S., Joosten, S., Keller, D., Khachatryan, G., Khachatryan, M., Khandaker, M., Kim, A., Kim, W., Klein, A., Kubarovsky, V., Kuleshov, S. V., Lanza, L., Lenisa, P., Livingston, K., MacGregor, I. J. D., Markov, N., McKinnon, B., Meyer, C. A., Meziani, Z. E., Mineeva, T., Mokeev, V., Montgomery, R. A., Movsisyan, A., Munevar, E., Camacho, C. Munoz, Nadel-Turonski, P., Net, L. A., Niccolai, S., Niculescu, G., Niculescu, I., Osipenko, M., Ostrovidov, A. I., Paolone, M., Paremuzyan, R., Park, K., Pasyuk, E., Phelps, W., Pisano, S., Pogorelko, O., Price, J. W., Procureur, S., Prok, Y., Protopopescu, D., Raue, B. A., Ripani, M., Rizzo, A., Rosner, G., Sabatie, F., Salgado, C., Schumacher, R. A., Sharabian, Y. G., Simonyan, A., Skorodumina, Iu., Smith, G. D., Sober, D. I., Sokhan, D., Sparveris, N., Stankovic, I., Stepanyan, S., Strakovsky, I. I., Strauch, S., Taiuti, M., Ungaro, M., Voskanyan, H., Voutier, E., Walford, N. K., Watts, D. P., Wei, X., Wood, M. H., Zachariou, N., Zhang, J., and Zhao, Z. W.
Subjects: Nuclear Experiment
Abstract: Photon beam asymmetry $\Sigma$ measurements for $\omega$ photoproduction in the reaction $\vec{\gamma} p \to \omega p$ 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 $\Sigma$ 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 $5/2^+$., Comment: 10 pages, 3 figures
Published: 2017
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8. Differential Cross Section Measurements for $\gamma n\to\pi^-p$ Above the First Nucleon Resonance Region

Author: Mattione, P. T., Carman, D. S., Strakovsky, I. I., Workman, R. L., Kudryavtsev, A. E., Svarc, A., Tarasov, V. E., Adhikari, K. P., Adhikari, S., Adikaram, D., Akbar, Z., Pereira, S. Anefalos, Ball, J., Baltzell, N. A., Bashkanov, M., Battaglieri, M., Batourine, V., Bedlinskiy, I., Biselli, A. S., Boiarinov, S., Briscoe, W. J., Burkert, V. D., Cao, T., Celentano, A., Charles, G., Chetry, T., Ciullo, G., Clark, L., Cole, P. L., Contalbrigo, M., Cortes, O., Crede, V., D'Angelo, A., Dashyan, N., De Vita, R., De Sanctis, E., Defurne, M., Deur, A., Djalali, C., Dugger, M., Dupre, R., Egiyan, H., Alaoui, A. El, Fassi, L. El, Eugenio, P., Fedotov, G., Fersch, R., Filippi, A., Fleming, J. A., Fradi, A., Ghandilyan, Y., Gilfoyle, G. P., Giovanetti, K. L., Girod, F. X., Gleason, C., Golovatch, E., Gothe, R. W., Griffioen, K. A., Guidal, M., Hafidi, K., Hakobyan, H., Hanretty, C., Harrison, N., Hattawy, M., Heddle, D., Hicks, K., Hollis, G., Holtrop, M., Hughes, S. M., Ilieva, Y., Ireland, D. G., Ishkhanov, B. S., Isupov, E. L., Jenkins, D., Jiang, H., Jo, H. S., Joo, K., Joosten, S., Keller, D., Khachatryan, G., Khachatryan, M., Khandaker, M., Kim, A., Kim, W., Klein, A., Klein, F. J., Kubarovsky, V., Kuleshov, S. V., Lanza, L., Lenisa, P., Livingston, K., MacGregor, I. J. D., Markov, N., McKinnon, B., Meyer, C. A., Meziani, Z. E., Mineeva, T., Mokeev, V., Montgomery, R. A., Movsisyan, A, Camacho, C. Munoz, Murdoch, G., Nadel-Turonski, P., Net, L. A., Niccolai, S., Niculescu, G., Niculescu, I., Osipenko, M., Ostrovidov, A. I., Paolone, M., Paremuzyan, R., Park, K., Pasyuk, E., Phelps, W., Pisano, S., Pogorelko, O., Price, J. W., Procureur, S., Prok, Y., Protopopescu, D., Raue, B. A., Ripani, M., Ritchie, B. G., Rizzo, A., Rosner, G., Sabatié, F., Salgado, C., Schumacher, R. A., Sharabian, Y. G., Simonyan, A., Skorodumina, Iu., Smith, G. D., Sokhan, D., Sparveris, N., Stankovic, I., Stepanyan, S., Strauch, S., Taiuti, M., Ungaro, M., Voskanyan, H., Voutier, E., Walford, N. K., Watts, D, Wei, X., Wood, M. H., Zachariou, N., Zhang, J., and Zhao, Z. W.
Subjects: Nuclear Experiment
Abstract: The quasi-free $\gamma d\to\pi^{-}p(p)$ differential cross section has been measured with CLAS at photon beam energies $E_\gamma$ from 0.445 GeV to 2.510 GeV (corresponding to $W$ from 1.311 GeV to 2.366 GeV) for pion center-of-mass angles $\cos\theta_\pi^{c.m.}$ from -0.72 to 0.92. A correction for final state interactions has been applied to this data to extract the $\gamma n\to\pi^-p$ differential cross sections. These cross sections are quoted in 8428 $(E_\gamma,\cos\theta_\pi^{c.m.})$ bins, a factor of nearly three 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 $N^* \to \gamma n$ at the resonance poles are determined for the first time and are reported here.
Published: 2017
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9. The Beam-Target Helicity Asymmetry for $\vec{\gamma} \vec{n} \rightarrow \pi^- p$ in the {\bf{$N^*$} Resonance Region

Author: Ho, D., Peng, P., Bass, C., Collins, P., D'Angelo, A., Deur, A., Fleming, J., Hanretty, C., Kageya, T., Khandaker, M., Klein, F. J., Klempt, E., Laine, V., Lowry, M. M., Lu, H., Nepali, C., Nikonov, V. A., O'Connell, T., Sandorfi, A. M., Sarantsev, A. V., Schumacher, R. A., Strakovsky, I. I., Švarc, A., Walford, N. K., Wei, X., Whisnant, C. S., Workman, R. L., Zonta, I., Adhikari, K. P., Adikaram, D., Akbar, Z., Amaryan, M. J., Pereira, S. Anefalos, Avakian, H., Ball, J., Bashkanov, M., Battaglieri, M., Batourine, V., Bedlinskiy, I., Briscoe, W. J., Burkert, V. D., Carman, D. S., Celentano, A., Charles, G., Chetry, T., Ciullo, G., Clark, L., Colaneri, L., Cole, P. L., Contalbrigo, M., Crede, V., Dashyan, N., De Sanctis, E., De Vita, R., Djalali, C., Dupre, R., Alaoui, A. El, Fassi, L. El, Elouadrhiri, L., Fedotov, G., Fegan, S., Fersch, R., Filippi, A., Fradi, A., Ghandilyan, Y., Gilfoyle, G. P., Girod, F. X., Glazier, D. I., Gleason, C., Gohn, W., Golovatch, E., Gothe, R. W., Griffioen, K. A., Guidal, M., Guo, L., Hakobyan, H., Harrison, N., Hicks, K., Holtrop, M., Hughes, S. M., Ilieva, Y., Ireland, D. G., Ishkhanov, B. S., Isupov, E. L., Jenkins, D., Jiang, H., Jo, H. S., Joo, K., Joosten, S., Keller, D., Khachatryan, G., Kim, A., Kim, W., Klein, A., Kubarovsky, V., Kuleshov, S. V., Lanza, L., Lenisa, P., Livingston, K., MacGregor, I . J . D., Markov, N., McKinnon, B., Mineeva, T., Mokeev, V., Montgomery, R. A., Movsisyan, A, Camacho, C. Munoz, Murdoch, G., Niccolai, S., Niculescu, G., Osipenko, M., Paolone, M., Paremuzyan, R., Park, K., Pasyuk, E., Phelps, W., Pogorelko, O., Price, J. W., Procureur, S., Protopopescu, D., Ripani, M., Riser, D., Ritchie, B. G., Rizzo, A., Rosner, G., Sabatié, F., Salgado, C., Sharabian, Y. G., Skorodumina, Iu., Smith, G. D., Sober, D. I., Sokhan, D., Sparveris, N., Strauch, S., Tian, Ye, Torayev, B., Ungaro, M., Voskanyan, H., Watts, D. P., Wood, M. H., Zachariou, N., Zhang, J., and Zhao, Z. W.
Subjects: Nuclear Experiment
Abstract: We report the first beam-target double-polarization asymmetries in the $\gamma + n(p) \rightarrow \pi^- + p(p)$ reaction spanning the nucleon resonance region from invariant mass $W$= $1500$ to $2300$ MeV. Circularly polarized photons and longitudinally polarized deuterons in $H\!D$ have been used with the CLAS detector at Jefferson Lab. The exclusive final state has been extracted using three very different analyses that show excellent agreement, and these have been used to deduce the {\it{E}} polarization observable for an effective neutron target. These results have been incorporated into new partial wave analyses, and have led to significant revisions for several $\gamma nN^*$ resonance photo-couplings., Comment: 6 pages, 5 figures; Physical Review Letters - in press
Published: 2017

10. Target and beam-target spin asymmetries in exclusive pion electroproduction for $Q^2>1$ GeV$^2$. II. $e p \rightarrow e \pi^0 p$

Author: Bosted, P. E., Kim, A., Adhikari, K. P., Adikaram, D., Akbar, Z., Amaryan, M. J., Pereira, S. Anefalos, Avakian, H., Badui, R. A., Ball, J., Balossino, I., Battaglieri, M., Bedlinskiy, I., Biselli, A. S., Boiarinov, S., Briscoe, W. J., Brooks, W. K., Bültmann, S., Burkert, V. D., Cao, T., Carman, D. S., Celentano, A., Chandavar, S., Charles, G., Chetry, T., Ciullo, G., Clark, L., Colaneri, L., Cole, P. L., Contalbrigo, M., Cortes, O., Crede, V., D'Angelo, A., Dashyan, N., De Vita, R., De Sanctis, E., Deur, A., Djalali, C., Dupre, R., Egiyan, H., Alaoui, A. El, Fassi, L. El, Elouadrhiri, L., Eugenio, P., Fanchini, E., Fedotov, G., Fegan, S., Fersch, R., Filippi, A., Fleming, J. A., Forest, T. A., Fradi, A., Ghandilyan, Y., Gilfoyle, G. P., Girod, F. X., Glazier, D. I., Gohn, W., Golovatch, E., Gothe, R. W., Griffioen, K. A., Guidal, M., Guler, N., Hakobyan, H., Guo, L., Hafidi, K., Hanretty, C., Harrison, N., Hattawy, M., Heddle, D., Hicks, K., Hollis, G., Holtrop, M., Hughes, S. M., Ireland, D. G., Isupov, E. L., Jenkins, D., Jiang, H., Jo, H. S., Joo, K., Keller, D., Khachatryan, G., Khandaker, M., Kim, W., Klei, A., Klein, F. J., Koirala, S., Kubarovsky, V., Kuhn, S. E., Lanza, L., Lenisa, P., Livingston, K., Lu, H. Y., MacGregor, I. J. D., Markov, N., Mayer, M., McCracken, M. E., McKinnon, B., Mineeva, T., Mirazita, M., Mokeev, V. I., Montgomery, R. A., Movsisyan, A, Camacho, C. Munoz, Murdoch, G., Nadel-Turonski, P., Ni, A., Niccolai, S., Niculescu, G., Osipenko, M., Ostrovidov, A. I., Paolone, M., Paremuzyan, R., Park, K., Pasyuk, E., Phelps, W., Pisano, S., Pogorelko, O., Price, J. W., Prok, Y., Protopopescu, D., Puckett, A. J. R., Raue, B. A., Ripani, M., Rizzo, A., Rosner, G., Rossi, P., Roy, P., Sabatié, F., Saini, M. S., Schumacher, R. A., Seder, E., Sharabian, Y. G., Skorodumina, Iu., Smith, G. D., Sokhan, D., Sparveris, N., Stankovic, I., Stepanyan, S., Stoler, P., Strakovsky, I. I., Strauch, S., Taiuti, M., Tian, Ye, Torayev, B., Ungaro, M., Voskanyan, H., Voutier, E., Walford, N. K., Watts, D. P., Wei, X., Weinstein, L. B., Zachariou, N., Zhang, J., Zhao, Z. W., and Zonta, I.
Subjects: Nuclear Experiment
Abstract: Beam-target double-spin asymmetries and target single-spin asymmetries were measured for the exclusive $\pi^0$ electroproduction reaction $\gamma^* p \to p \pi^0$, expanding an analysis of the $\gamma^* p \to n \pi^+$ reaction from the same experiment. The results were obtained from scattering of 6 GeV longitudinally polarized electrons off longitudinally polarized protons using the CEBAF Large Acceptance Spectrometer at Jefferson Lab. The kinematic range covered is $1.1
Published: 2016
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11. Measurement of Target and Double-spin Asymmetries for the $\vec e\vec p\to e\pi^+ (n)$ Reaction in the Nucleon Resonance Region at Low $Q^2$

Author: Zheng, X., Adhikari, K. P., Bosted, P., Deur, A., Drozdov, V., Fassi, L. El, Kang, Hyekoo, Kovacs, K., Kuhn, S., Long, E., Phillips, S. K., Ripani, M., Slifer, K., Smith, L. C., Adikaram, D., Akbar, Z., Amaryan, M. J., Pereira, S. Anefalos, Asryan, G., Avakian, H., Badui, R. A., Ball, J., Baltzell, N. A., Battaglieri, M., Batourine, V., Bedlinskiy, I., Biselli, A. S., Briscoe, W. J., Bültmann, S., Burkert, V. D., Carman, D. S., Celentano, A., Chandavar, S., Charles, G., Chen, J. -P., Chetry, T., Choi, Seonho, Ciullo, G., Clark, L., Colaneri, L., Cole, P. L., Compton, N., Contalbrigo, M., Crede, V., D'Angelo, A., Dashyan, N., De Vita, R., De Sanctis, E., Djalali, C., Dodge, G. E., Dupre, R., Egiyan, H., Alaoui, A. El, Elouadrhiri, L., Eugenio, P., Fanchini, E., Fedotov, G., Fersch, R., Filippi, A., Fleming, J. A., Gevorgyan, N., Ghandilyan, Y., Gilfoyle, G. P., Giovanetti, K. L., Girod, F. X., Gleason, C., Golovach, E., Gothe, R. W., Griffioen, K. A., Guidal, M., Guler, N., Guo, L., Hanretty, C., Harrison, N., Hattawy, M., Hicks, K., Holtrop, M., Hughes, S. M., Ilieva, Y., Ireland, D. G., Ishkhanov, B. S., Isupov, E. L., Jenkins, D., Jiang, H., Jo, H. S., Joosten, S., Keller, D., Khachatryan, G., Khandaker, M., Kim, A., Kim, W., Klein, F. J., Kubarovsky, V., Lanza, L., Lenisa, P., Livingston, K., MacGregor, I . J . D., Markov, N., McKinnon, B., Mirazita, M., Mokeev, V., Movsisyan, A., Munevar, E., Camacho, C. Munoz, Murdoch, G., Nadel-Turonski, P., Net, L. A., Ni, A., Niccolai, S., Niculescu, G., Niculescu, I., Osipenko, M., Ostrovidov, A. I., Paolone, M., Paremuzyan, R., Park, K., Pasyuk, E., Peng, P., Pisano, S., Pogorelko, O., Price, J. W., Puckett, A. J. R., Raue, B. A., Rizzo, A., Rosner, G., Rossi, P., Roy, P., Sabatié, F., Salgado, C., Schumacher, R. A., Sharabian, Y. G., Skorodumina, Iu., Smith, G. D., Sokhan, D., Sparveris, N., Stankovic, I., Strakovsky, I. I., Strauch, S., Taiuti, M., Tian, Ye, Ungaro, M., Voskanyan, H., Voutier, E., Walford, N. K., Watts, D. P., Wei, X., Weinstein, L. B., Wood, M. H., Zachariou, N., and Zhang, J.
Subjects: Nuclear Experiment
Abstract: We report measurements of target- and double-spin asymmetries for the exclusive channel $\vec e\vec p\to e\pi^+ (n)$ in the nucleon resonance region at Jefferson Lab using the CEBAF Large Acceptance Spectrometer (CLAS). These asymmetries were extracted from data obtained using a longitudinally polarized NH$_3$ target and a longitudinally polarized electron beam with energies 1.1, 1.3, 2.0, 2.3 and 3.0 GeV. The new results are consistent with previous CLAS publications but are extended to a low $Q^2$ range from $0.0065$ to $0.35$ (GeV$/c$)$^2$. The $Q^2$ access was made possible by a custom-built Cherenkov detector that allowed the detection of electrons for scattering angles as low as $6^\circ$. These results are compared with the unitary isobar models JANR and MAID, the partial-wave analysis prediction from SAID and the dynamic model DMT. In many kinematic regions our results, in particular results on the target asymmetry, help to constrain the polarization-dependent components of these models., Comment: 20 pages, 15 figures, to appear in Phys. Rev. C
Published: 2016
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12. Target and Beam-Target Spin Asymmetries in Exclusive $\pi^+$ and $\pi^-$ Electroproduction with 1.6 to 5.7 GeV Electrons

Author: Bosted, P. E., Biselli, A. S., Careccia, S., Dodge, G., Fersch, R., Kuhn, S. E., Pierce, J., Prok, Y., Zheng, X., Adhikari, K. P., Adikaram, D., Akbar, Z., Amaryan, M. J., Pereira, S. Anefalos, Asryan, G., Avakian, H., Badui, R. A., Ball, J., Baltzell, N. A., Battaglieri, M., Batourine, V., Bedlinskiy, I., Boiarinov, S., Briscoe, W. J., Bültmann, S., Burkert, V. D., Cao, T., Carman, D. S., Celentano, A., Chandavar, S., Charles, G., Chetry, T., Ciullo, G., Clark, L., Colaneri, L., Cole, P. L., Contalbrigo, M., Cortes, O., Crede, V., D'Angelo, A., Dashyan, N., De Vita, R., Deur, A., Djalali, C., Dupre, R., Egiyan, H., Alaoui, A. El, Fassi, L. El, Eugenio, P., Fanchini, E., Fedotov, G., Filippi, A., Fleming, J. A., Forest, T. A., Fradi, A., Garçon, M., Gevorgyan, N., Ghandilyan, Y., Gilfoyle, G. P., Giovanetti, K. L., Girod, F. X., Gleason, C., Gohn, W., Golovatch, E., Gothe, R. W., Griffioen, K. A., Guler, N., Guo, L., Hafidi, K., Hanretty, C., Harrison, N., Hattawy, M., Heddle, D., Hicks, K., Holtrop, M., Hughes, S. M., Ilieva, Y., Ireland, D. G., Ishkhanov, B. S., Isupov, E. L., Jenkins, D., Jiang, H., Jo, H. S., Joo, K., Joosten, S., Keller, D., Khandaker, M., Kim, W., Klein, A., Klein, F. J., Kubarovsky, V., Kuleshov, S. V., Lanza, L., Lenisa, P., Livingston, K., Lu, H. Y., MacGregor, I . J . D., Markov, N., McCracken, M. E., McKinnon, B., Meyer, C. A., Minehart, R., Mirazita, M., Mokeev, V., Movsisyan, A, Munevar, E., Camacho, C. Munoz, Nadel-Turonski, P., Net, L. A., Ni, A., Niccolai, S., Niculescu, G., Niculescu, I., Osipenko, M., Ostrovidov, A. I., Paremuzyan, R., Park, K., Pasyuk, E., Peng, P., Phelps, W., Pisano, S., Pogorelko, O., Price, J. W., Procureur, S., Protopopescu, D., Puckett, A. J. R., Raue, B. A., Ripani, M., Rizzo, A., Rosner, G., Rossi, P., Roy, P., Sabatié, F., Salgado, C., Schumacher, R. A., Seder, E., Sharabian, Y. G., Simonyan, A., Skorodumina, Iu., Smith, G. D., Sparveris, N., Stankovic, Ivana, Stepanyan, S., Strakovsky, I. I., Strauch, S., Sytnik, V., Taiuti, M., Tian, Ye, Torayev, B., Ungaro, M., Voskanyan, H., Voutier, E., Walford, N. K., Watts, D. P., Wei, X., Weinstein, L. B., Wood, M. H., Zachariou, N., Zana, L., Zhang, J., Zhao, Z. W., and Zonta, I.
Subjects: Nuclear Experiment
Abstract: Beam-target double spin asymmetries and target single-spin asymmetries in exclusive $\pi^+$ and $\pi^-$ electroproduction were obtained from scattering of 1.6 to 5.7 GeV longitudinally polarized electrons from longitudinally polarized protons (for $\pi^+$) and deuterons (for $\pi^-$) using the CEBAF Large Acceptance Spectrometer (CLAS) at Jefferson Lab. The kinematic range covered is $1.11.5$ GeV. Very large target-spin asymmetries are observed for $W>1.6$ GeV. When combined with cross section measurements, the present results will provide powerful constraints on nucleon resonance amplitudes at moderate and large values of $Q^2$, for resonances with masses as high as 2.3 GeV., Comment: 47 pages, 24 figures. This is a revised version that was accepted for publication in Phys. Rev. C. in early October, 2016
Published: 2016
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13. Measurement of two-photon exchange effect by comparing elastic $e^\pm p$ cross sections

Author: Rimal, D., Adikaram, D., Raue, B. A., Weinstein, L. B., Arrington, J., Brooks, W. K., Ungaro, M., Adhikari, K. P., Akbar, Z., Pereira, S. Anefalos, Badui, R. A., Ball, J., Baltzell, N. A., Battaglieri, M., Batourine, V., Bedlinskiy, I., Bennett, R. P., Biselli, A. S., Boiarinov, S., Briscoe, W. J., Bültmann, S., Carman, D. S., Celentano, A., Chetry, T., Ciullo, G., Clark, L., Colaneri, L., Cole, P. L., Compton, N., Contalbrigo, M., Cortes, O., Crede, V., D'Angelo, A., Dashyan, N., De Vita, R., Deur, A., Djalali, C., Dupre, R., Egiyan, H., Alaoui, A. El, Fassi, L. El, Eugenio, P., Fedotov, G., Fersch, R., Filippi, A., Fleming, J. A., Forest, T. A., Fradi, A., Gevorgyan, N., Ghandilyan, Y., Gilfoyle, G. P., Giovanetti, K. L., Girod, F. X., Gleason, C., Gohn, W., Golovatch, E., Gothe, R. W., Griffioen, K. A., Guo, L., Hafidi, K., Hanretty, C., Harrison, N., Hattawy, M., Heddle, D., Hicks, K., Holtrop, M., Hughes, S. M., Ilieva, Y., Ireland, D. G., Ishkhanov, B. S., Isupov, E. L., Jenkins, D., Jiang, H., Joosten, S., Keller, D., Khetarpal, P., Khachatryan, G., Khandaker, M., Kim, W., Klein, A., Klein, F. J., Kubarovsky, V., Kuhn, S. E., Kuleshov, S. V., Lanza, L., Lenisa, P., Livingston, K., Lu, H. Y., MacGregor, I . J . D., Markov, N., McKinnon, B., Mestayer, M. D., Mirazita, M., Mokeev, V., Movsisyan, A, Munevar, E., Camacho, C. Munoz, Nadel-Turonski, P., Ni, A., Niccolai, S., Niculescu, G., Niculescu, I., Osipenko, M., Ostrovidov, A. I., Paolone, M., Paremuzyan, R., Park, K., Pasyuk, E., Phelps, W., Pisano, S., Pogorelko, O., Price, J. W., Prok, Y., Protopopescu, D., Puckett, A. J. R., Rizzo, A., Rosner, G., Rossi, P., Roy, P., Sabatié, F., Salgado, C., Schumacher, R. A., Seder, E., Sharabian, Y. G., Skorodumina, Iu., Smith, G. D., Sokhan, D., Sparveris, N., Stankovic, Ivana, Stepanyan, S., Strauch, S., Sytnik, V., Taiuti, M., Torayev, B., Voskanyan, H., Voutier, E., Walford, N. K., Watts, D. P., Wei, X., Wood, M. H., Zachariou, N., Zana, L., Zhang, J., Zhao, Z. W., and Zonta, I.
Subjects: Nuclear Experiment
Abstract: [Background] The electromagnetic form factors of the proton measured by unpolarized and polarized electron scattering experiments show a significant disagreement that grows with the squared four momentum transfer ($Q^{2}$). Calculations have shown that the two measurements can be largely reconciled by accounting for the contributions of two-photon exchange (TPE). TPE effects are not typically included in the standard set of radiative corrections since theoretical calculations of the TPE effects are highly model dependent, and, until recently, no direct evidence of significant TPE effects has been observed. [Purpose] We measured the ratio of positron-proton to electron-proton elastic-scattering cross sections in order to determine the TPE contribution to elastic electron-proton scattering and thereby resolve the proton electric form factor discrepancy. [Methods] We produced a mixed simultaneous electron-positron beam in Jefferson Lab's Hall B by passing the 5.6 GeV primary electron beam through a radiator to produce a bremsstrahlung photon beam and then passing the photon beam through a convertor to produce electron/positron pairs. The mixed electron-positron (lepton) beam with useful energies from approximately 0.85 to 3.5 GeV then struck a 30-cm long liquid hydrogen (LH$_2$) target located within the CEBAF Large Acceptance Spectrometer (CLAS). By detecting both the scattered leptons and the recoiling protons we identified and reconstructed elastic scattering events and determined the incident lepton energy. A detailed description of the experiment is presented., Comment: 21 pages, 22 figures
Published: 2016
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14. A search for baryon- and lepton-number violating decays of $\Lambda$ hyperons using the CLAS detector at Jefferson Laboratory

Author: McCracken, M. E., Bellis, M., Adhikari, K. P., Adikaram, D., Akbar, Z., Pereira, S. Anefalos, Badui, R. A., Ball, J., Baltzell, N. A., Battaglieri, M., Batourine, V., Bedlinskiy, I., Biselli, A. S., Boiarinov, S., Briscoe, W. J., Brooks, W. K., Burkert, V. D., Cao, T., Carman, D. S., Celentano, A., Chandavar, S., Charles, G., Colaneri, L., Cole, P. L., Contalbrigo, M., Cortes, O., Crede, V., D'Angelo, A., Dashyan, N., De Vita, R., De Sanctis, E., Deur, A., Djalali, C., Dodge, G. E., Dupre, R., Alaoui, A. El, Fassi, L. El, Elouadrhiri, E., Eugenio, P., Fedotov, G., Fegan, S., Fersch, R., Filippi, A., Fleming, J. A., Garillon, B., Gevorgyan, N., Gilfoyle, G. P., Giovanetti, K. L., Girod, F. X., Golovatch, E., Gothe, R. W., Griffioen, K. A., Guidal, M., Guo, L., Hafidi, K., Hakobyan, H., Hanretty, C., Hattawy, M., Hicks, K., Holtrop, M., Hughes, S. M., Ilieva, Y., Ireland, D. G., Ishkhanov, B. S., Isupov, E. L., Jenkins, D., Jiang, H., Jo, H. S., Keller, D., Khachatryan, G., Khandaker, M., Kim, A., Kim, W., Klein, A., Klein, F. J., Kubarovsky, V., Lenisa, P., Livingston, K., Lu, H. Y., MacGregor, I. J. D., Mayer, M., McKinnon, B., Mestayer, M. D., Meyer, C. A., Mirazita, M., Mokeev, V., Moody, C. I., Moriya, K., Camacho, C. Munoz, Nadel-Turonski, P., Net, L. A., Niccolai, S., Osipenko, M., Ostrovidov, A. I., Park, K., Pasyuk, E., Pisano, S., Pogorelko, O., Price, J. W., Procureur, S., Prok, Y., Raue, B. A., Ripani, M., Rizzo, A., Rosner, G., Roy, P., Sabatié, F., Salgado, C., Schumacher, R. A., Seder, E., Sharabian, Y. G., Skorodumina, Iu., Sokhan, D., Sparveris, N., Stoler, P., Strakovsky, I. I., Strauch, S., Sytnik, V., Tian, Ye, Ungaro, M., Voskanyan, H., Voutier, E., Walford, N. K., Watts, D. P., Wei, X., Wood, M. H., Zachariou, N., Zana, L., Zhang, J., Zhao, Z. W., and Zonta, I.
Subjects: High Energy Physics - Experiment, Nuclear Experiment
Abstract: We present a search for ten baryon-number violating decay modes of $\Lambda$ hyperons using the CLAS detector at Jefferson Laboratory. Nine of these decay modes result in a single meson and single lepton in the final state ($\Lambda \rightarrow m \ell$) and conserve either the sum or the difference of baryon and lepton number ($B \pm L$). The tenth decay mode ($\Lambda \rightarrow \bar{p}\pi^+$) represents a difference in baryon number of two units and no difference in lepton number. We observe no significant signal and set upper limits on the branching fractions of these reactions in the range $(4-200)\times 10^{-7}$ at the $90\%$ confidence level., Comment: 12 pages, 7 figures (color)
Published: 2015
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15. First measurement of the helicity asymmetry $E$ in $\eta$ photoproduction on the proton

Author: Senderovich, I., Morrison, B. T., Dugger, M., Ritchie, B. G., Pasyuk, E., Tucker, R., Brock, J., Carlin, C., Keith, C. D., Meekins, D. G., Seely, M. L., R, D., D, M., Collins, P., Adhikari, K. P., Adikaram, D., Akbar, Z., Anderson, M. D., Pereira, S. Anefalos, Badui, R. A., Ball, J., Baltzell, N. A., Battaglieri, M., Batourine, V., Bedlinskiy, I., Biselli, A. S., Boiarinov, S., Briscoe, W. J., Brooks, W. K., Burkert, V. D., Carman, D. S., Celentano, A., Chandavar, S., Charles, G., Colaneri, L., Cole, P. L., Contalbrigo, M., Cortes, O., Crede, V., D'Angelo, A., Dashyan, N., De Vita, R., De Sanctis, E., Deur, A., Djalali, C., Dupre, R., Egiyan, H., Alaoui, A. El, Fassi, L. El, Fradi, A., Elouadrhiri, L., Eugenio, P., Fedotov, G., Fegan, S., Filippi, A., Fleming, J. A., Garillon, B., Ghandilyan, Y., Gilfoyle, G. P., Giovanetti, K. L., Girod, F. -X., Glazier, D. I., Goetz, J. T., Gohn, W., Golovatch, E., Gothe, R. W., Griffioen, K. A., Guidal, M., Guo, L., Hafidi, K., Hakobyan, H., Hanretty, C., Hattawy, M., Hicks, K., Ho, D., Holtrop, M., Hughes, S. M., Ilieva, Y., Ireland, D. G., Ishkhanov, B. S., Jenkins, D., Jiang, H., Jo, H. S., Joo, K., Joosten, S., Keller, D., Khachatryan, G., Khandaker, M., Kim, A., Klein, F. J., Kubarovsky, V., Kunkel, M. C., Lenisa, P., Livingston, K., Lu, H. Y., MacGregor, I. J. D., Mattione, P., McKinnon, B., Meyer, C. A., Mineeva, T., Mokeev, V., Montgomery, R. A., Movsisyan, A., Camacho, C. Munoz, Nadel-Turonski, P., Net, L. A., Niccolai, S., Niculescu, G., Niculescu, I., Osipenko, M., Park, K., Park, S., Peng, P., Phelps, W., Pisano, S., Pogorelko, O., Price, J. W., Prok, Y., Puckett, A. J. R., Ripani, M., Rizzo, A., Rosner, G., Roy, P., Sabatie, F., Salgado, C., Schott, D., Schumacher, R. A., Seder, E., Simonyan, A., Skorodumina, Iu., Smith, G. D., Sober, D. I., Sokhan, D., Sparveris, N., Stepanyan, S., Stoler, P., Strakovsky, I. I., Strauch, S., Sytnik, V., Tian, Ye, Ungaro, M., Voskanyan, H., Voutier, E., Walford, N. K., Wei, X., Wood, M. H., Zachariou, N., Zana, L., Zhang, J., Zhao, Z. W., and Zonta, I.
Subjects: Nuclear Experiment
Abstract: Results are presented for the first measurement of the double-polarization helicity asymmetry E for the $\eta$ photoproduction reaction $\gamma p \rightarrow \eta p$. 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 J\"ulich 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 using that model. Further comparison with several theoretical approaches indicates these data will significantly enhance our understanding of nucleon resonances.
Published: 2015
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16. Precise Determination of the Deuteron Spin Structure at Low to Moderate $Q^2$ with CLAS and Extraction of the Neutron Contribution

Author: Guler, N., Fersch, R. G., Kuhn, S. E., Bosted, P., Griffioen, K. A., Keith, C., Minehart, R., Prok, Y., Adhikari, K. P., Adikaram, D., Amaryan, M. J., Anderson, M. D., Pereira, S. Anefalos, Ball, J., Battaglieri, M., Batourine, V., Bedlinskiy, I., Briscoe, W. J., Brooks, W. K., Bultmann, S., Burkert, V. D., Carman, D. S., Celentano, A., Chandavar, S., Charles, G., Colaneri, L., Cole, P. L., Contalbrigo, M., Crabb, D., Crede, V., Angelo, A. D, Dashyan, N., Deur, A., Djalali, C., Dodge, G. E., Dupre, R., Alaoui, A. El, Fassi, L. El, Elouadrhiri, L., Eugenio, P., Fedotov, G., Fegan, S., Filippi, A., Fleming, J. A., Forest, T. A., Garillon, B., Garcon, M., Gevorgyan, N., Gilfoyle, G. P., Giovanetti, K. L., Girod, F. X., Goetz, J. T., Golovatch, E., Gothe, R. W., Guidal, M., Guo, L., Hafidi, K., Hakobyan, H., Harrison, N., Hattawy, M., Hicks, K., Ho, D., Holtrop, M., Hughes, S. M., Hyde, C. E., Ireland, D. G., Ishkhanov, B. S., Isupov, E. L., Jo, H. S., Joo, K., Joosten, S., Keller, D., Khandaker, M., Kim, A., Kim, W., Klein, A., Klein, F. J., Kubarovsky, V., Kuleshov, S. V., Livingston, K., Lu, H. Y., MacGregor, I. J. D., McKinnon, B., Mirazita, M., Mokeev, V., Montgomery, R. A., Movsisyan, A, Camacho, C. Munoz, Nadel-Turonski, P., Net, L. A., Niculescu, I., Osipenko, M., Ostrovidov, A. I., Park, K., Pasyuk, E., Pisano, S., Pogorelko, O., Price, J. W., Procureur, S., Ripani, M., Rizzo, A., Rosner, G., Rossi, P., Roy, P., Sabatie, F., Salgado, C., Schott, D., Schumacher, R. A., Seder, E., Simonyan, A., Skorodumina, Iu., Sokhan, D., Sparveris, N., Strakovsky, I. I., Strauch, S., Sytnik, V., Tian, Ye, Tkachenko, S., Ungaro, M., Voutier, E., Walford, N. K., Wei, X., Weinstein, L. B., Wood, M. H., Zachariou, N., Zana, L., Zhang, J., Zhao, Z. W., and Zonta, I.
Subjects: Nuclear Experiment
Abstract: We present the final results for the deuteron spin structure functions obtained from the full data set collected with Jefferson Lab's CLAS in 2000-2001. Polarized electrons with energies of 1.6, 2.5, 4.2 and 5.8 GeV were scattered from deuteron ($^{15}$ND$_3$) targets, dynamically polarized along the beam direction, and detected with CLAS. From the measured double spin asymmetry, the virtual photon absorption asymmetry $A_1^d$ and the polarized structure function $g_1^d$ were extracted over a wide kinematic range (0.05 GeV$^2 < Q^2 <$ 5 GeV$^2$ and 0.9 GeV $< W <$ 3 GeV). We use an unfolding procedure and a parametrization of the corresponding proton results to extract from these data the polarized structure functions $A_1^n$ and $g_1^n$ of the (bound) neutron, which are so far unknown in the resonance region, $W < 2$ GeV. We compare our final results, including several moments of the deuteron and neutron spin structure functions, with various theoretical models and expectations as well as parametrizations of the world data. The unprecedented precision and dense kinematic coverage of these data can aid in future extractions of polarized parton distributions, tests of perturbative QCD predictions for the quark polarization at large $x$, a better understanding of quark-hadron duality, and more precise values for higher-twist matrix elements in the framework of the Operator Product Expansion., Comment: To be published in Phys. Rev. C
Published: 2015
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17. Determination of the Beam-Spin Asymmetry of Deuteron Photodisintegration in the Energy Region $E_\gamma=1.1-2.3$ GeV

Author: Zachariou, Nicholas, Ilieva, Yordanka, Ivanov, Nikolay Ya., Sargsian, Misak M, Avakian, Robert, Feldman, Gerald, Nadel-Turonski, Pawel, Adhikari, K. P., Adikaram, D., Anderson, M. D., Pereira, S. Anefalos, Avakian, H., Badui, R. A., Baltzell, N. A., Battaglieri, M., Baturin, V., Bedlinskiy, I., Biselli, A. S., Briscoe, W. J., Brooks, W. K., Burkert, V. D., Cao, T., Carman, D. S., Celentano, A., Chandavar, S., Charles, G., Colaneri, L., Cole, P. L., Compton, N., Contalbrigo, M., Cortes, O., Crede, V., D'Angelo, A., De Vita, R., De Sanctis, E., Deur, A., Djalali, C., Dupre, R., Egiyan, H., Alaoui, A. El, Fassi, L. El, Elouadrhiri, L., Fedotov, G., Fegan, S., Filippi, A., Fleming, J. A., Forest, T. A., Fradi, A., Gevorgyan, N., Ghandilyan, Y., Gilfoyle, G. P., Giovanetti, K. L., Girod, F. X., Glazier, D. I., Golovatch, E., Gothe, R. W., Griffioen, K. A., Guidal, M., Hafidi, K., Hanretty, C., Harrison, N., Hattawy, M., Hicks, K., Ho, D., Holtrop, M., Hughes, S. M., Ireland, D. G., Ishkhanov, B. S., Isupov, E. L., Jiang, H., Jo, H. S., Joo, K., Keller, D., Khachatryan, G., Khandaker, M., Kim, A., Kim, W., Klein, F. J., Kubarovsky, V., Lenisa, P., Livingston, K., Lu, H. Y., MacGregor, I . J . D., Markov, N., Mattione, P. T., McKinnon, B., Mineeva, T., Mirazita, M., Mokeeev, V. I., Montgomery, R. A., Moutarde, H., Camacho, C. Munoz, Net, L. A., Niccolai, S., Niculescu, G., Niculescu, I., Osipenko, M., Ostrovidov, A. I., Park, K., Pasyuk, E., Phelps, W., Phillips, J. J., Pisano, S., Pogorelko, O., Pozdniakov, S., Price, J. W., Procureur, S., Prok, Y., Protopopescu, D., Puckett, A. J. R., Ripani, M., Rizzo, A., Rosner, G., Rossi, P., Roy, P., Sabatié, F., Salgado, C., Schott, D., Schumacher, R. A., Seder, E., Senderovich, I., Sharabian, Y. G., Skorodumina, Iu., Smith, G. D., Sober, D. I., Sokhan, D., Sparveris, N., Stepanyan, S., Strauch, S., Sytnik, V., Taiuti, M., Tian, Ye, Ungaro, M., Voskanyan, H., Voutier, E., Walford, N. K., Watts, D., Wei, X., Wood, M. H., Zana, L., Zhang, J., Zhao, Z. W., and Zonta, I.
Subjects: Nuclear Experiment
Abstract: The beam-spin asymmetry, $\Sigma$, for the reaction $\gamma d\rightarrow pn$ has been measured using the CEBAF Large Acceptance Spectrometer (CLAS) at the Thomas Jefferson National Accelerator Facility (JLab) for six photon-energy bins between 1.1 and 2.3 GeV, and proton angles in the center-of-mass frame, $\theta_{c.m.}$, between $25^\circ$ and $160^\circ$. These are the first measurements of beam-spin asymmetries at $\theta_{c.m.}=90^\circ$ for photon-beam energies above 1.6 GeV, and the first measurements for angles other than $\theta_{c.m.}=90^\circ$. The angular and energy dependence of $\Sigma$ is expected to aid in the development of QCD-based models to understand the mechanisms of deuteron photodisintegration in the transition region between hadronic and partonic degrees of freedom, where both effective field theories and perturbative QCD cannot make reliable predictions., Comment: 18 pages
Published: 2015
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18. First Measurement of the Polarization Observable E in the $\vec p(\vec \gamma,\pi^+)n$ Reaction up to 2.25 GeV

Author: Strauch, S., Briscoe, W. J., Döring, M., Klempt, E., Nikonov, V. A., Pasyuk, E., Rönchen, D., Sarantsev, A. V., Strakovsky, I., Workman, R., Adhikari, K. P., Adikaram, D., Anderson, M. D., Pereira, S. Anefalos, Anisovich, A. V., Badui, R. A., Ball, J., Batourine, V., Battaglieri, M., Bedlinskiy, I., Benmouna, N., Biselli, A. S., Brock, J., Brooks, W. K., Burkert, V. D., Cao, T., Carlin, C., Carman, D. S., Celentano, A., Chandavar, S., Charles, G., Colaneri, L., Cole, P. L., Compton, N., Contalbrigo, M., Cortes, O., Crede, V., Dashyan, N., D'Angelo, A., De Vita, R., De Sanctis, E., Deur, A., Djalali, C., Dugger, M., Dupre, R., Egiyan, H., Alaoui, A. El, Fassi, L. El, Elouadrhiri, L., Eugenio, P., Fedotov, G., Fegan, S., Filippi, A., Fleming, J. A., Forest, T. A., Fradi, A., Gevorgyan, N., Ghandilyan, Y., Giovanetti, K. L., Girod, F. X., Glazier, D. I., Gohn, W., Golovatch, E., Gothe, R. W., Griffioen, K. A., Guidal, M., Guo, L., Hafidi, K., Hakobyan, H., Hanretty, C., Harrison, N., Hattawy, M., Hicks, K., Ho, D., Holtrop, M., Hughes, S. M., Ilieva, Y., Ireland, D. G., Ishkhanov, B. S., Isupov, E. L., Jenkins, D., Jiang, H., Jo, H. S., Joo, K., Joosten, S., Keith, C. D., Keller, D., Khachatryan, G., Khandaker, M., Kim, A., Kim, W., Klein, A., Klein, F. J., Kubarovsky, V., Kuhn, S. E., Lenisa, P., Livingston, K., Lu, H. Y., MacGregor, I . J . D., Markov, N., McKinnon, B., Meekins, D. G., Meyer, C. A., Mokeev, V., Montgomery, R. A., Moody, C. I., Moutarde, H., Movsisyan, A, Munevar, E., Camacho, C. Munoz, Nadel-Turonski, P., Net, L. A., Niccolai, S., Niculescu, G., Niculescu, I., Osipenko, M., Ostrovidov, A. I., Park, K., Peng, P., Phelps, W., Phillips, J. J., Pisano, S., Pogorelko, O., Pozdniakov, S., Price, J. W., Procureur, S., Prok, Y., Protopopescu, D., Puckett, A. J. R., Raue, B. A., Ripani, M., Ritchie, B. G., Rizzo, A., Rosner, G., Roy, P., Sabatié, F., Salgado, C., Schott, D., Schumacher, R. A., Seder, E., Seely, M. L., Senderovich, I, Sharabian, Y. G., Simonyan, A., Skorodumina, Iu., Smith, G. D., Sober, D. I., Sokhan, D., Sparveris, N., Stoler, P., Stepanyan, S., Sytnik, V., Taiuti, M., Tian, Ye, Trivedi, A., Tucker, R., Ungaro, M., Voskanyan, H., Voutier, E., Walford, N. K., Watts, D. P., Wei, X., Wood, M. H., Zachariou, N., Zana, L., Zhang, J., Zhao, Z. W., and Zonta, I.
Subjects: Nuclear Experiment, High Energy Physics - Experiment
Abstract: First results from the longitudinally polarized frozen-spin target (FROST) program are reported. The double-polarization observable E, for the reaction $\vec \gamma \vec p \to \pi^+n$, 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, J\"ulich, and SAID groups., Comment: 6 pages, 3 figures
Published: 2015
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19. Towards a resolution of the proton form factor problem: new electron and positron scattering data

Author: Adikaram, D., Rimal, D., Weinstein, L. B., Raue, B., Khetarpal, P., Bennett, R. P., Arrington, J., Brooks, W. K., Adhikari, K. P., Afanasev, A. V., Amaryan, M. J., Anderson, M. D., Ball, J., Battaglieri, M., Bedlinskiy, I., Biselli, A. S., Bono, J., Boiarinov, S., Briscoe, W. J., Burkert, V. D., Carman, D. S., Celentano, A., Chandavar, S., Charles, G., Colaneri, L., Cole, P. L., Contalbrigo, M., D'Angelo, A., Dashyan, N., De Vita, R., De Sanctis, E., Deur, A., Djalali, C., Dodge, G. E., Dupre, R., Egiyan, H., Alaoui, A. El, Fassi, L. El, Eugenio, P., Fedotov, G., Fegan, S., Filippi, A., Fleming, J. A., Fradi, A., Gilfoyle, G. P., Giovanetti, K. L., Girod, F. X., Goetz, J. T., Gohn, W., Golovatch, E., Gothe, R. W., Griffioen, K. A., Guidal, M., Guo, L., Hafidi, K., Hakobyan, H., Harrison, N., Hattawy, M., Hicks, K., Holtrop, M., Hughes, S. M., Hyde, C. E., Ilieva, Y., Ireland, D. G., Ishkhanov, B. S., Jenkins, D., Jiang, H., Joo, K., Joosten, S., Khandaker, M., Kim, W., Klein, A., Klein, F. J., Koirala, S., Kubarovsky, V., Kuhn, S. E., Lu, H. Y., MacGregor, I . J . D., Markov, N., Mayer, M., McKinnon, B., Mestayer, M. D., Meyer, C. A., Mirazita, M., Mokeev, V., Montgomery, R. A., Moody, C. I., Moutarde, H., Movsisyan, A, Camacho, C. Munoz, Nadel-Turonski, P., Niccolai, S., Niculescu, G., Osipenko, M., Ostrovidov, A. I., Park, K., Pasyuk, E., Pisano, S., Pogorelko, O., Procureur, S., Prok, Y., Protopopescu, D., Puckett, A. J. R., Ripani, M., Rizzo, A., Rosner, G., Rossi, P., Sabatié, F., Schott, D., Schumacher, R. A., Sharabian, Y. G., Simonyan, A., Skorodumina, I., Smith, E. S., Smith, G. D., Sober, D. I., Sparveris, N., Stepanyan, S., Strauch, S., Sytnik, V., Taiuti, M., Tian, Ye, Trivedi, A., Ungaro, M., Voskanyan, H., Voutier, E., Walford, N. K., Watts, D. P., Wei, X., Wood, M. H., Zachariou, N., Zana, L., Zhang, J., Zhao, Z. W., Zonta, I., and Collaboration, The CLAS
Subjects: Nuclear Experiment
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 ($\varepsilon$) and momentum transfer ($Q^2$) simultaneously, as well as to cancel luminosity-related systematic errors. The cross section ratio increases with decreasing $\varepsilon$ at $Q^2 = 1.45 \text{ GeV}^2$. This measurement is consistent with the size of the form factor discrepancy at $Q^2\approx 1.75$ GeV$^2$ and with hadronic calculations including nucleon and $\Delta$ intermediate states, which have been shown to resolve the discrepancy up to $2-3$ GeV$^2$., Comment: 6 pages, 4 figures, submitted to PRL
Published: 2014
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20. Induced polarization of {\Lambda}(1116) in kaon electroproduction

Author: Gabrielyan, M., Raue, B. A., Carman, D. S., Park, K., Adhikari, K. P., Adikaram, D., Amaryan, M. J., Pereira, S. Anefalos, Avakian, H., Ball, J., Baltzell, N. A., Battaglieri, M., Baturin, V., Bedlinskiy, I., Biselli, A. S., Bono, J., Boiarinov, S., Briscoe, W. J., Brooks, W. K., Burkert, V. D., Cao, T., Celentano, A., Chandavar, S., Charles, G., Cole, P. L., Contalbrigo, M., Cortes, O., Crede, V., DAngelo, A., Dashyan, N., De Vita, R., De Sanctis, E., Deur, A., Djalali, C., Doughty, D., Dupre, R., Fassi, L. El, Eugenio, P., Fedotov, G., Fegan, S., Fleming, J. A., Forest, T. A., Garillon, B., Gevorgyan, N., Ghandilyan, Y., Gilfoyle, G. P., Giovanetti, K. L., Girod, F. X., Goetz, J. T., Golovatch, E., Gothe, R. W., Griffioen, K. A., Guidal, M., Guo, L., Hafidi, K., Hakobyan, H., Hattawy, M., Hicks, K., Ho, D., Holtrop, M., Hughes, S. M., Ilieva, Y., Ireland, D. G., Ishkhanov, B. S., Jenkins, D., Jiang, H., Jo, H. S., Joo, K., Keller, D., Khandaker, M., Kim, W., Klein, F. J., Koirala, S., Kubarovsky, V., Kuhn, S. E., Kuleshov, S. V., Lenisa, P., Levine, W. I., Livingston, K., MacGregor, I. J. D., Mayer, M., McKinnon, B., Meyer, C. A., Mestayer, M. D., Mirazita, M., Mokeev, V., Moody, C. I., Moutarde, H., Movsisyan, A, Munevar, E., Camacho, C. Munoz, Nadel-Turonski, P., Niccolai, S., Niculescu, G., Osipenko, M., Pappalardo, L. L., Paremuzyan, R., Pasyuk, E., Peng, P., Phelps, W., Phillips, J. J., Pisano, S., Pogorelko, O., Pozdniakov, S., Price, J. W., Procureur, S., Protopopescu, D., Rimal, D., Ripani, M., Rizzo, A., Sabatie, F., Salgado, C., Schott, D., Schumacher, R. A., Simonyan, A., Smith, G. D., Sober, D. I., Sokhan, D., Stepanyan, S. S., Stepanyan, S., Strakovsky, I. I., Strauch, S., Sytnik, V., Tang, W., Ungaro, M., Vlassov, A. V., Voskanyan, H., Voutier, E., Walford, N. K., Watts, D. P., Wei, X., Weinstein, L. B., Zachariou, N., Zana, L., and Zhang, J.
Subjects: Nuclear Experiment
Abstract: We have measured the induced polarization of the ${\Lambda}(1116)$ in the reaction $ep\rightarrow e'K^+{\Lambda}$, detecting the scattered $e'$ and $K^+$ in the final state along with the proton from the decay $\Lambda\rightarrow p\pi^-$.The present study used the CEBAF Large Acceptance Spectrometer (CLAS), which allowed for a large kinematic acceptance in invariant energy $W$ ($1.6\leq W \leq 2.7$ GeV) and covered the full range of the kaon production angle at an average momentum transfer $Q^2=1.90$ GeV$^2$.In this experiment a 5.50 GeV electron beam was incident upon an unpolarized liquid-hydrogen target. We have mapped out the $W$ and kaon production angle dependencies of the induced polarization and found striking differences from photoproduction data over most of the kinematic range studied. However, we also found that the induced polarization is essentially $Q^2$ independent in our kinematic domain, suggesting that somewhere below the $Q^2$ covered here there must be a strong $Q^2$ dependence. Along with previously published photo- and electroproduction cross sections and polarization observables, these data are needed for the development of models, such as effective field theories, and as input to coupled-channel analyses that can provide evidence of previously unobserved $s$-channel resonances., Comment: 13 figures
Published: 2014
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21. Precision measurements of $g_1$ of the proton and the deuteron with 6 GeV electrons

Author: Prok, Y., Bosted, P., Kvaltine, N., Adhikari, K. P., Adikaram, D., Aghasyan, M., Amaryan, M. J., Anderson, M. D., Pereira, S. Anefalos, Avakian, H., Baghdasaryan, H., Ball, J., Baltzell, N. A., Battaglieri, M., Biselli, A. S., Bono, J., Briscoe, W. J., Brock, J., Brooks, W. K., Bültmann, S., Burkert, V. D., Carlin, C., Carman, D. S., Celentano, A., Chandavar, S., Colaneri, L., Cole, P. L., Contalbrigo, M., Cortes, O., Crabb, D., Crede, V., D'Angelo, A., Dashyan, N., De Vita, R., De Sanctis, E., Deur, A., Djalali, C., Dodge, G. E., Doughty, D., Dupre, R., Alaoui, A. El, Fassi, L. El, Elouadrhiri, L., Fedotov, G., Fegan, S., Fersch, R., Fleming, J. A., Forest, T. A., Garcon, M., Gevorgyan, N., Ghandilyan, Y., Gilfoyle, G. P., Girod, F. X., Giovanetti, K. L., Goetz, J. T., Gohn, W., Gothe, R. W., Griffioen, K. A., Guegan, B., Guler, N., Haffidi, K., Hanretty, C., Harrison, N., Hattawy, M., Hicks, K., Ho, D., Holtrop, M., Ilieva, Y., Ireland, D. G., Ishkhanov, B. S., Isupov, E. L., Jawalkar, S., Jiang, X., Jo, H. S., Joo, K., Kalantarians, N., Keith, C., Keller, D., Khandaker, M., Kim, A., Kim, W., Klein, A., Klein, F. J., Koirala, S., Kubarovsky, V., Kuhn, S. E., Kuleshov, S. V., Lenisa, P., Livingston, K., Lu, H. Y., MacGregor, I . J. D., Markov, N., Mayee, M., McKinnon, B., Meekins, D., Mineeva, T., Mirazita, M., Mokeev, V., Montgomery, R. A., Moutarde, H., Movsisyan, A, Munevar, E., Camacho, C. Munoz, Nadel-Turonski, P., Niccolai, S., Niculescu, G., Niculescu, I., Osipenko, M., Ostrovidov, A. I., Pappalardo, L. L., Paremuzyan, R., Park, K., Peng, P., Phillips, J. J., Pierce, J., Pisano, S., Pogorelko, O., Pozdniakov, S., Price, J. W., Procureur, S., Protopopescu, D., Puckett, A. J. R., Raue, B. A., Rimal, D., Ripani, M., Rizzo, A., Rosner, G., Rossi, P., Roy, P., Sabatié, F., Saini, M. S., Salgado, C., Schott, D., Schumacher, R. A., Seder, E., Sharabian, Y. G., Simonyan, A., Smith, C., Smith, G., Sober, D. I., Sokhan, D., Stepanyan, S. S., Stepanyan, S., Strakovsky, I. I., Strauch, S., Sytnik, V., Taiuti, M., Tang, W., Tkachenko, S., Ungaro, M., Vernarsky, B ., Vlassov, A. V., Voskanyan, H., Voutier, E., Walford, N. K., Watts, D . P., Weinstein, L. B., Zachariou, N., Zana, L., Zhang, J., Zhao, B., Zhao, Z. W., and Zonta, I.
Subjects: Nuclear Experiment
Abstract: The inclusive polarized structure functions of the proton and deuteron, g1p and g1d, were measured with high statistical precision using polarized 6 GeV electrons incident on a polarized ammonia target in Hall B at Jefferson Laboratory. Electrons scattered at lab angles between 18 and 45 degrees were detected using the CEBAF Large Acceptance Spectrometer (CLAS). For the usual DIS kinematics, Q^2>1 GeV^2 and the final-state invariant mass W>2 GeV, the ratio of polarized to unpolarized structure functions g1/F1 is found to be nearly independent of Q^2 at fixed x. Significant resonant structure is apparent at values of W up to 2.3 GeV. In the framework of perturbative QCD, the high-W results can be used to better constrain the polarization of quarks and gluons in the nucleon, as well as high-twist contributions.
Published: 2014
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22. Demonstration of a novel technique to measure two-photon exchange effects in elastic $e^\pm p$ scattering

Author: Moteabbed, M., Niroula, M., Raue, B. A., Weinstein, L. B., Adikaram, D., Arrington, J., Brooks, W. K., Lachniet, J., Rimal, Dipak, Ungaro, M., Adhikari, K. P., Aghasyan, M., Amaryan, M. J., Pereira, S. Anefalos, Avakian, H., Ball, J., Baltzell, N. A., Battaglieri, M., Batourine, V., Bedlinskiy, I., Bennett, R. P., Biselli, A. S., Bono, J., Boiarinov, S., Briscoe, W. J., Burkert, V. D., Carman, D. S., Celentano, A., Chandavar, S., Cole, P. L., Collins, P., Contalbrigo, M., Cortes, O., Crede, V., D'Angelo, A., Dashyan, N., De Vita, R., De Sanctis, E., Deur, A., Djalali, C., Doughty, D., Dupre, R., Egiyan, H., Fassi, L. El, Eugenio, P., Fedotov, G., Fegan, S., Fersch, R., Fleming, J. A., Gevorgyan, N., Gilfoyle, G. P., Giovanetti, K. L., Girod, F. X., Goetz, J. T., Gohn, W., Golovatch, E., Gothe, R. W., Griffioen, K. A., Guidal, M., Guler, N., Guo, L., Hafidi, K., Hakobyan, H., Hanretty, C., Harrison, N., Heddle, D., Hicks, K., Ho, D., Holtrop, M., Hyde, C. E., Ilieva, Y., Ireland, D. G., Ishkhanov, B. S., Isupov, E. L., Jo, H. S., Joo, K., Keller, D., Khandaker, M., Kim, A., Klein, F. J., Koirala, S., Kubarovsky, A., Kubarovsky, V., Kuhn, S. E., Kuleshov, S. V., Lewis, S., Lu, H. Y., MacCormick, M., MacGregor, I . J . D., Martinez, D., Mayer, M., McKinnon, B., Mineeva, T., Mirazita, M., Mokeev, V., Montgomery, R. A., Moriya, K., Moutarde, H., Munevar, E., Camacho, C. Munoz, Nadel-Turonski, P., Nasseripour, R., Niccolai, S., Niculescu, G., Niculescu, I., Osipenko, M., Ostrovidov, A. I., Pappalardo, L. L., Paremuzyan, R., Park, K., Park, S., Phelps, E., Phillips, J. J., Pisano, S., Pogorelko, O., Pozdniakov, S., Price, J. W., Procureur, S., Protopopescu, D., Puckett, A. J. R., Ripani, M., Rosner, G., Rossi, P., Sabatié, F., Saini, M. S., Salgado, C., Schott, D., Schumacher, R. A., Seder, E., Seraydaryan, H., Sharabian, Y. G., Smith, E. S., Smith, G. D., Sober, D. I., Sokhan, D., Stepanyan, S., Strauch, S., Tang, W., Taylor, C. E., Tian, Ye, Tkachenko, S., Voskanyan, H., Voutier, E., Walford, N. K., Wood, M. H., Zachariou, N., Zana, L., Zhang, J., Zhao, Z. W., and Zonta, I.
Subjects: Nuclear Experiment
Abstract: The discrepancy between proton electromagnetic form factors extracted using unpolarized and polarized scattering data is believed to be a consequence of two-photon exchange (TPE) effects. However, the calculations of TPE corrections have significant model dependence, and there is limited direct experimental evidence for such corrections. We present the results of a new experimental technique for making direct $e^\pm p$ comparisons, which has the potential to make precise measurements over a broad range in $Q^2$ and scattering angles. We use the Jefferson Lab electron beam and the Hall B photon tagger to generate a clean but untagged photon beam. The photon beam impinges on a converter foil to generate a mixed beam of electrons, positrons, and photons. A chicane is used to separate and recombine the electron and positron beams while the photon beam is stopped by a photon blocker. This provides a combined electron and positron beam, with energies from 0.5 to 3.2 GeV, which impinges on a liquid hydrogen target. The large acceptance CLAS detector is used to identify and reconstruct elastic scattering events, determining both the initial lepton energy and the sign of the scattered lepton. The data were collected in two days with a primary electron beam energy of only 3.3 GeV, limiting the data from this run to smaller values of $Q^2$ and scattering angle. Nonetheless, this measurement yields a data sample for $e^\pm p$ with statistics comparable to those of the best previous measurements. We have shown that we can cleanly identify elastic scattering events and correct for the difference in acceptance for electron and positron scattering. The final ratio of positron to electron scattering: $R=1.027\pm0.005\pm0.05$ for $=0.206$ GeV$^2$ and $0.830\leq \epsilon\leq 0.943$.
Published: 2013
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23. Near Threshold Neutral Pion Electroproduction at High Momentum Transfers and Generalized Form Factors

Author: Khetarpal, P., Stoler, P., Aznauryan, I. G., Kubarovsky, V., Adhikari, K. P., Adikaram, D., Aghasyan, M., Amaryan, M. J., Anderson, M. D., Pereira, S. Anefalos, Anghinolfi, M., Avakian, H., Baghdasaryan, H., Ball, J., Baltzell, N. A., Battaglieri, M., Batourine, V., Bedlinskiy, I., Biselli, A. S., Bono, J., Boiarinov, S., Briscoe, W. J., Brooks, W. K., Burkert, V. D., Carman, D. S., Celentano, A., Charles, G., Cole, P. L., Contalbrigo, M., Crede, V., D'Angelo, A., Dashyan, N., De Vita, R., De Sanctis, E., Deur, A., Djalali, C., Doughty, D., Dugger, M., Dupre, R., Egiyan, H., Alaoui, A. El, Fassi, L. El, Eugenio, P., Fedotov, G., Fegan, S., Fersch, R., Fleming, J. A., Fradi, A., Gabrielyan, M. Y., Garçon, M., Gevorgyan, N., Gilfoyle, G. P., Giovanetti, K. L., Girod, F. X., Goetz, J. T., Gohn, W., Golovatch, E., Gothe, R. W., Griffioen, K. A., Guegan, B., Guidal, M., Guo, L., Hafidi, K., Hakobyan, H., Hanretty, C., Harrison, N., Hicks, K., Ho, D., Holtrop, M., Hyde, C. E., Ilieva, Y., Ireland, D. G., Ishkhanov, B. S., Isupov, E. L., Jo, H. S., Joo, K., Keller, D., Khandaker, M., Kim, A., Kim, W., Klein, F. J., Koirala, S., Kubarovsky, A., Kuleshov, S. V., Kvaltine, N. D., Lewis, S., Livingston, K., Lu, H. Y., MacGregor, I. J. D., Mao, Y., Martinez, D., Mayer, M., McKinnon, B., Meyer, C. A., Mineeva, T., Mirazita, M., Mokeev, V., Montgomery, R. A., Moutarde, H., Munevar, E., Camacho, C. Munoz, Nadel-Turonski, P., Nasseripour, R., Niccolai, S., Niculescu, G., Niculescu, I., Osipenko, M., Ostrovidov, A. I., Pappalardo, L. L., Paremuzyan, R., Park, K., Park, S., Pasyuk, E., Phelps, E., Phillips, J. J., Pisano, S., Pogorelko, O., Pozdniakov, S., Price, J. W., Procureur, S., Protopopescu, D., Puckett, A. J. R., Raue, B. A., Ricco, G., Rimal, D., Ripani, M., Rosner, G., Rossi, P., Sabatié, F., Saini, M. S., Salgado, C., Saylor, N. A., Schott, D., Schumacher, R. A., Seder, E., Seraydaryan, H., Sharabian, Y. G., Smith, G. D., Sober, D. I., Sokhan, D., Stepanyan, S. S., Stepanyan, S., Strakovsky, I. I., Strauch, S., Taiuti, M., Tang, W., Taylor, C. E., Tkachenko, S., Ungaro, M., Vernarsky, B., Voskanyan, H., Voutier, E., Walford, N. K., Weinstein, L. B., Weygand, D. P., Wood, M. H., Zachariou, N., Zhang, J., Zhao, Z. W., and Zonta, I.
Subjects: Nuclear Experiment
Abstract: We report the measurement of near threshold neutral pion electroproduction cross sections and the extraction of the associated structure functions on the proton in the kinematic range $Q^2$ from 2 to 4.5 GeV$^2$ and $W$ from 1.08 to 1.16 GeV. These measurements allow us to access the dominant pion-nucleon s-wave multipoles $E_{0+}$ and $S_{0+}$ in the near-threshold region. In the light-cone sum-rule framework (LCSR), these multipoles are related to the generalized form factors $G_1^{\pi^0 p}(Q^2)$ and $G_2^{\pi^0 p}(Q^2)$. The data are compared to these generalized form factors and the results for $G_1^{\pi^0 p}(Q^2)$ are found to be in good agreement with the LCSR predictions, but the level of agreement with $G_2^{\pi^0 p}(Q^2)$ is poor., Comment: 17 pages, 18 figures, Journal article (Physical Review C)
Published: 2012
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24. Evidence for the Onset of Color Transparency in $\rho^0$ Electroproduction off Nuclei

Author: Fassi, L. El, Zana, L., Hafidi, K., Holtrop, M., Mustapha, B., Brooks, W. K., Hakobyan, H., Zheng, X., Adhikari, K. P., Adikaram, D., Aghasyan, M., Amaryan, M. J., Anghinolfi, M., Arrington, J., Avakian, H., Baghdasaryan, H., Battaglieri, M., Batourine, V., Bedlinskiy, I., Biselli, A. S., Bookwalter, C., Branford, D., Briscoe, W. J., Bultmann, S., Burkert, V. D., Carman, D. S., Celentano, A., Chandavar, S., Cole, P. L., Contalbrigo, M., Crede, V., D'Angelo, A., Daniel, A., Dashyan, N., De Vita, R., De Sanctis, E., Deur, A., Dey, B., Dickson, R., Djalali, C., Dodge, G. E., Doughty, D., Dupre, R., Egiyan, H., Alaoui, A. El, Elouadrhiri, L., Eugenio, P., Fedotov, G., Fegan, S., Gabrielyan, M. Y., Garcon, M., Gevorgyan, N., Gilfoyle, G. P., Giovanetti, K. L., Girod, F. X., Goetz, J. T., Gohn, W., Golovatch, E., Gothe, R. W., Griffioen, K. A., Guidal, M., Guo, L., Hanretty, C., Heddle, D., Hicks, K., Holt, R. J., Hyde, C. E., Ilieva, Y., Ireland, D. G., Ishkhanov, B. S., Isupov, E. L., Jawalkar, S. S., Keller, D., Khandaker, M., Khetarpal, P., Kim, A., Kim, W., Klein, A., Klein, F. J., Kubarovsky, V., Kuhn, S. E., Kuleshov, S. V., Kuznetsov, V., Laget, J. M., Lu, H. Y., MacGregor, I. J. D., Mao, Y., Markov, N., Mayer, M., McAndrew, J., McKinnon, B., Meyer, C. A., Mineeva, T., Mirazita, M., Mokeev, V., Moreno, B., Moutarde, H., Munevar, E., Nadel-Turonski, P., Ni, A., Niccolai, S., Niculescu, G., Niculescu, I., Osipenko, M., Ostrovidov, A. I., Pappalardo, L., Paremuzyan, R., Park, K., Park, S., Pasyuk, E., Pereira, S. Anefalos, Phelps, E., Pisano, S., Pozdniakov, S., Price, J. W., Procureur, S., Protopopescu, D., Raue, B. A., Reimer, P. E., Ricco, G., Rimal, D., Ripani, M., Ritchie, B. G., Rosner, G., Rossi, P., Sabatie, F., Saini, M. S., Salgado, C., Schott, D., Schumacher, R. A., Seraydaryan, H., Sharabian, Y. G., Smith, E. S., Smith, G. D., Sober, D. I., Sokhan, D., Stepanyan, S. S., Stepanyan, S., Stoler, P., Strauch, S., Taiuti, M., Tang, W., Taylor, C. E., Tedeschi, D. J., Tkachenko, S., Ungaro, M., Vernarsky, B ., Vineyard, M. F., Voskanyan, H., Voutier, E., Watts, D., Weinstein, L. B., Weygand, D. P., Wood, M. H., Zachariou, N., Zhao, B., and Zhao, Z. W.
Subjects: Nuclear Experiment
Abstract: We have measured the nuclear transparency of the incoherent diffractive $A(e,e'\rho^0)$ process in $^{12}$C and $^{56}$Fe targets relative to $^2$H using a 5 GeV electron beam. The nuclear transparency, the ratio of the produced $\rho^0$'s on a nucleus relative to deuterium, which is sensitive to $\rho A$ interaction, was studied as function of the coherence length ($l_c$), a lifetime of the hadronic fluctuation of the virtual photon, and the four-momentum transfer squared ($Q^2$). While the transparency for both $^{12}$C and $^{56}$Fe showed no $l_c$ dependence, a significant $Q^2$ dependence was measured, which is consistent with calculations that included the color transparency effects., Comment: 6 pages and 4 figures
Published: 2012
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25. Measurement of the neutron F2 structure function via spectator tagging with CLAS

Author: Baillie, N., Tkachenko, S., Zhang, J., Bosted, P., Bultmann, S., Christy, M. E., Fenker, H., Griffioen, K. A., Keppel, C. E., Kuhn, S. E., Melnitchouk, W., Tvaskis, V., Adhikari, K. P., Adikaram, D., Aghasyan, M., Amaryan, M. J., Anghinolfini, M., Arrington, J., Avakian, H., Baghdasaryan, H., Battaglieri, M., Biselli, A. S., Branford, 5 D., Briscoe, W. J., Brooks, W. K., Burkert, V. D., Carman, D. S., Celentano, A., Chandavar, S., Charles, G., Cole, P. L., Contalbrigo, M., Crede, V., D'Angelo, A., Daniel, A., Dashyan, N., De Vita, R., De Sanctis, E., Deur, A., Dey, B., Djalali, C., Dodge, G., Domingo, J., Doughty, D., Dupre, R., Dutta, D., Ent, R., Egiyan, H., Alaoui, A. El, Fassi, L. El, Elouadrhiri, L., Eugenio, P., Fedotov, G., Fegan, S., Fradi, A., Gabrielyan, M. Y., Gevorgyan, N., Gilfoyle, G. P., Giovanetti, K. L., Girod, F. X., Gohn, W., Golovatch, E., Gothe, R. W., Graham, L., Guegan, B., Guidal, M., Guler, N., Guo, L., Hafidi, K., Heddle, D., Hicks, K., Holtrop, M., Hungerford, E., Hyde, C. E., Ilieva, Y., Ireland, D. G., Ispiryan, M., Isupov, E. L., Jawalkar, S. S., Jo, H. S., Kalantarians, N., Khandaker, M., Khetarpal, P., Kim, A., Kim, W., King, P. M., Klein, A., Klein, F. J., Klimenko, A., Kubarovsky, V., Kuleshov, S. V., Kvaltine, N. D., Livingston, K., Lu, H. Y., MacGregor, I . J . D., Mao, Y., Markov, N., McKinnon, B., Mineeva, T., Morrison, B., Moutarde, H., Munevar, E., Nadel-Turonski, P., Ni, A., Niccolai, S., Niculescu, I., Niculescu, G., Osipenko, M., Ostrovidov, A. I., Pappalardo, L., Park, K., Park, S., Pasyuk, E., Pereira, S. Anefalos, Pisano, S., Pozdniakov, S., Price, J. W., Procureur, S., Prok, Y., Protopopescu, D., Raue, B. A., Ricco, G., Rimal, D., Ripani, M., Rosner, G., Rossi, P., Sabatie, F., Saini, M. S., Salgado, C., Schott, D., Schumacher, R. A., Seder, E., Sharabian, Y. G., Sober, D. I., Sokhan, D., Stepanyan, S., Stepanyan, S. S., Stoler, P., Strauch, S., Taiuti, M., Tang, W., Ungaro, M., Vineyard, M. F., Voutier, E., Watts, D. P., Weinstein, L. B., Weygand, D. P., Wood, M. H., Zana, L., and Zhao, B.
Subjects: Nuclear Experiment, High Energy Physics - Experiment
Abstract: We report on the first measurement of the F2 structure function of the neutron from semi-inclusive scattering of electrons from deuterium, with low-momentum protons detected in the backward hemisphere. Restricting the momentum of the spectator protons to < 100 MeV and their angles to < 100 degrees relative to the momentum transfer allows an interpretation of the process in terms of scattering from nearly on-shell neutrons. The F2n data collected cover the nucleon resonance and deep-inelastic regions over a wide range of Bjorken x for 0.65 < Q2 < 4.52 GeV2, with uncertainties from nuclear corrections estimated to be less than a few percent. These measurements provide the first determination of the neutron to proton structure function ratio F2n/F2p at 0.2 < x < 0.8 with little uncertainty due to nuclear effects., Comment: 6 pages, 3 pages
Published: 2011
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26. Precise Measurements of Beam Spin Asymmetries in Semi-Inclusive $\pi^0$ production

Author: Aghasyan, M., Avakian, H., Rossi, P., De Sanctis, E., Hasch, D., Mirazita, M., Adikaram, D., Amaryan, M. J., Anghinolfi, M., Baghdasaryan, H., Ball, J., Battaglieri, M., Batourine, V., Bedlinskiy, I., Bennett, R. P., Biselli, A. S., Branford, D., Briscoe, W. J., Bültmann, S., Burkert, V. D., Carman, D. S., Chandavar, S., Cole, P. L., Collins, P., Contalbrigo, M., Crede, V., D'Angelo, A., Daniel, A., Dashyan, N., De Vita, R., Deur, A., Dey, B., Dickson, R., Djalali, C., Dodge, G. E., Doughty, D., Dupre, R., Egiyan, H., Alaoui, A. El, Elouadrhiri, L., Eugenio, P., Fedotov, G., Fegan, S., Fradi, A., Gabrielyan, M. Y., Garçon, M., Gevorgyan, N., Gilfoyle, G. P., Giovanetti, K. L., Girod, F. X., Goetz, J. T., Gohn, W., Golovatch, E., Gothe, R. W., Graham, L., Griffioen, K. A., Guegan, B., Guidal, M., Guler, N., Guo, L., Hafidi, K., Hanretty, C., Hicks, K., Holtrop, M., Hyde, C. E., Ilieva, Y., Ireland, D. G., Isupov, E. L., Jawalkar, S. S., Jenkins, D., Jo, H. S., Joo, K., Keller, D., Khandaker, M., Khetarpal, P., Kim, A., Kimy, W., Klein, A., Klein, F. J., Kubarovsky, V., Kuhn, S. E., Kuleshov, S. V., Kuznetsov, V., Kvaltine, N. D., Livingston, K., Lu, H. Y., MacGregor, I . J . D., Markov, N., Mayer, M., McAndrew, J., McKinnon, B., Meyer, C. A., Micherdzinska, A. M., Mokeev, V., Moreno, B., Moutarde, H., Munevar, E., Nadel-Turonski, P., Ni, A., Niccolai, S., Niculescu, G., Niculescu, I., Osipenko, M., Ostrovidov, A. I., Paolone, M., Pappalardo, L., Paremuzyan, R., Park, K., Park, S., Pasyuk, E., Pereira, S. Anefalos, Phelps, E., Pisano, S., Pogorelko, O., Pozdniakov, S., Price, J. W., Procureur, S., Prok, Y., Protopopescu, D., Raue, B. A., Ricco, G., Rimal, D., Ripani, M., Rosner, G., Sabatié, F., Saini, M. S., Salgado, C., Schott, D., Schumacher, R. A., Seder, E., Seraydaryan, H., Sharabian, Y. G., Smith, G. D., Sober, D. I., Stepanyan, S. S., Stepanyan, S., Stoler, P., Strakovsky, I., Strauch, S., Taiuti, M., Tang, W., Taylor, C. E., Tkachenko, S., Ungaro, M., Voskanyan, H., Voutier, E., Watts, D., Weinstein, L. B., Weygand, D. P., Wood, M. H., Zana, L., Zhang, J., Zhao, B., and Zhao, Z. W.
Subjects: High Energy Physics - Experiment
Abstract: We present studies of single-spin asymmetries for neutral pion electroproduction in semi-inclusive deep-inelastic scattering of 5.776 GeV polarized electrons from an unpolarized hydrogen target, using the CEBAF Large Acceptance Spectrometer (CLAS) at the Thomas Jefferson National Accelerator Facility. A substantial $\sin \phi_h$ amplitude has been measured in the distribution of the cross section asymmetry as a function of the azimuthal angle $\phi_h$ of the produced neutral pion. The dependence of this amplitude on Bjorken $x$ and on the pion transverse momentum is extracted with significantly higher precision than previous data and is compared to model calculations., Comment: to be submitted PLB
Published: 2011
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26 results on '"Adikaram D"'

1. Deeply virtual Compton scattering cross section at high Bjorken $x_B$

2. Form Factors and Two-Photon Exchange in High-Energy Elastic Electron-Proton Scattering

3. Deep exclusive electroproduction of $\pi^0$ at high $Q^2$ in the quark valence regime

4. Beam-Target Helicity Asymmetry $E$ in $K^{0}\Lambda$ and $K^{0}\Sigma^0$ Photoproduction on the Neutron

5. Semi-Inclusive $\pi_0$ target and beam-target asymmetries from 6 GeV electron scattering with CLAS

6. First Exclusive Measurement of Deeply Virtual Compton Scattering off $^4$He: Toward the 3D Tomography of Nuclei

7. Photon beam asymmetry $\Sigma$ in the reaction $\vec{\gamma} p \to p \omega$ for $E_\gamma$ = 1.152 to 1.876 GeV

8. Differential Cross Section Measurements for $\gamma n\to\pi^-p$ Above the First Nucleon Resonance Region

9. The Beam-Target Helicity Asymmetry for $\vec{\gamma} \vec{n} \rightarrow \pi^- p$ in the {\bf{$N^*$} Resonance Region

10. Target and beam-target spin asymmetries in exclusive pion electroproduction for $Q^2>1$ GeV$^2$. II. $e p \rightarrow e \pi^0 p$

11. Measurement of Target and Double-spin Asymmetries for the $\vec e\vec p\to e\pi^+ (n)$ Reaction in the Nucleon Resonance Region at Low $Q^2$

12. Target and Beam-Target Spin Asymmetries in Exclusive $\pi^+$ and $\pi^-$ Electroproduction with 1.6 to 5.7 GeV Electrons

13. Measurement of two-photon exchange effect by comparing elastic $e^\pm p$ cross sections

14. A search for baryon- and lepton-number violating decays of $\Lambda$ hyperons using the CLAS detector at Jefferson Laboratory

15. First measurement of the helicity asymmetry $E$ in $\eta$ photoproduction on the proton

16. Precise Determination of the Deuteron Spin Structure at Low to Moderate $Q^2$ with CLAS and Extraction of the Neutron Contribution

17. Determination of the Beam-Spin Asymmetry of Deuteron Photodisintegration in the Energy Region $E_\gamma=1.1-2.3$ GeV

18. First Measurement of the Polarization Observable E in the $\vec p(\vec \gamma,\pi^+)n$ Reaction up to 2.25 GeV

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

20. Induced polarization of {\Lambda}(1116) in kaon electroproduction

21. Precision measurements of $g_1$ of the proton and the deuteron with 6 GeV electrons

22. Demonstration of a novel technique to measure two-photon exchange effects in elastic $e^\pm p$ scattering

23. Near Threshold Neutral Pion Electroproduction at High Momentum Transfers and Generalized Form Factors

24. Evidence for the Onset of Color Transparency in $\rho^0$ Electroproduction off Nuclei

25. Measurement of the neutron F2 structure function via spectator tagging with CLAS

26. Precise Measurements of Beam Spin Asymmetries in Semi-Inclusive $\pi^0$ production

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