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1. Center of mass motion of short-range correlated nucleon pairs studied via the A(e,e'pp) reaction

Author: Cohen, E O, Hen, O, Piasetzky, E, Weinstein, L B, Duer, M, Schmidt, A, Korover, I, Hakobyan, H, Adhikari, S, Akbar, Z, Amaryan, M J, Avakian, H, Ball, J, Barion, L, Battaglieri, M, Beck, A, Bedlinskiy, I, Biselli, A S, Boiarinov, S, Briscoe, W, Burkert, V D, Cao, F, Carman, D S, Celentano, A, Charles, G, Chatagnon, Pierre, Chetry, T, Ciullo, G, Clary, Brandon A, Contalbrigo, M, Crede, V, Cruz Torres, R, D'Angelo, A, Dashyan, N, De Vita, R, De Sanctis, E, Defurne, M, Deur, A, Diehl, S, Djalali, C, Dupre, R, Egiyan, H, Ehrhart, Mathieu, El Alaoui, A, Fassi, L El, Eugenio, P, Fedotov, G, Fersch, R, Filippi, A, Ghandilyan, Y, Giovanetti, K L, Girod, F X, Golovatch, E, Gothe, R W, Griffioen, K A, Hafidi, K, Harrison, N, Hauenstein, F, Heddle, D, Hicks, K, Holtrop, M, 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, Klein, F J, Kubarovsky, V, Kuhn, S E, Lanza, L, Lenisa, P, Livingston, K., MacGregor, I.J.D., Marchand, D, McKinnon, B., Mey-Tal Beck, S, Meyer, C A, Mirazita, M, Mokeev, V, Montgomery, R.A., Movsisyan, A, Munoz Camacho, C, Mustapha, B, Nadel-Turonski, P, Niccolai, S, Niculescu, G, Osipenko, M, Ostrovidov, A I, Paolone, M, Paremuzyan, R, Pasyuk, E, Pogorelko, O, Price, J W, Prok, Y, Protopopescu, D., Ripani, M, Riser, D, Rizzo, A, Rosner, G., Rossi, P, Sabatié, F, Schmookler, B A, Schumacher, R A, Sharabian, Y G, Sokhan, D., Sparveris, N, Stepanyan, S, Strauch, S, Taiuti, M, Tan, J A, Ungaro, M, Voskanyan, H, Voutier, E, Wang, R, Watts, D P, Wei, X, Wood, M H, Zachariou, N, Zhang, J, Zheng, X, and Zhao, Z W
Subjects: Nuclear Theory, Nuclear Experiment
Abstract: Short-range correlated (SRC) nucleon pairs are a vital part of the nucleus, accounting for almost all nucleons with momentum greater than the Fermi momentum (k_{F}). A fundamental characteristic of SRC pairs is having large relative momenta as compared to k_{F}, and smaller center of mass (c.m.) which indicates a small separation distance between the nucleons in the pair. Determining the c.m. momentum distribution of SRC pairs is essential for understanding their formation process. We report here on the extraction of the c.m. motion of proton-proton (pp) SRC pairs in carbon and, for the first time in heavier and ansymetric nuclei: aluminum, iron, and lead, from measurements of the A(e,e^{'}pp) reaction. We find that the pair c.m. motion for these nuclei can be described by a three-dimensional Gaussian with a narrow width ranging from 140 to 170 MeV/c, approximately consistent with the sum of two mean-field nucleon momenta. Comparison with calculations appears to show that the SRC pairs are formed from mean-field nucleons in specific quantum states.
Published: 2018

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

Author: Kunkel, M. C., Amaryan, M. J., Strakovsky, I. I., Ritman, J., Goldstein, G. R., Adhikari, K. P., Adhikari, S., Avakian, H., Ball, J., Balossino, I., Barion, L., Battaglieri, M., Batourine, V., Bedlinskiy, I., Biselli, A. S., Boiarinov, S., Briscoe, W. J., Brooks, W. K., Bultmann, S., Burkert, V. D., Cao, F., Carman, D. S., 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., Degtyarenko, P. V., Defurne, M., Deur, A., Djalali, C., Dugger, M., Dupre, R., Egiyan, H., El Alaoui, A., El Fassi, L., Elouadrhiri, L., Eugenio, P., Fedotov, G., Fersch, R., Filippi, A., Fradi, A., Gavalian, G., Ghandilyan, Y., Ghosh, S., Gilfoyle, G. P., Giovanetti, K. L., Girod, F. X., Glazier, D. I., Gohn, W., Golovatch, E., Gothe, R. W., Griffioen, K. A., Guo, L., Guidal, M., Hafidi, K., Hakobyan, H., Harrison, N., Hattawy, M., Hicks, K., Holtrop, M., Hyde, C. E., Ireland, D. G., Ishkhanov, B. S., Isupov, E. L., Jenkins, D., Joo, K., Kabir, M. L., Keller, D., Khachatryan, G., Khachatryan, M., Khandaker, M., Kim, A., Kim, W., Klein, A., Klein, F., Kubarovsky, V., Kuhn, S. E., Laget, J. M., Lanza, L., Lenisa, P., Lersch, D., Livingston, K., Macgregor, I. J. D., Markov, N., Mbianda Njencheu, G., Mckinnon, B., Mineeva, T., Mokeev, V., Montgomery, R. A., Movsisyan, A., Munoz Camacho, C., Nadel-Turonski, P., Niccolai, S., Niculescu, G., Osipenko, M., Ostrovidov, A. I., Paolone, M., Park, K., Pasyuk, E., Payette, D., Phelps, W., Pogorelko, O., Poudel, J., Price, J. W., Procureur, S., Prok, Y., Protopopescu, D., Ripani, M., Ritchie, B. G., Rizzo, A., Rosner, G., Roy, A., Sabatie, F., Salgado, C., Schadmand, S., Schumacher, R. A., Sharabian, Y. G., Skorodumina, I., Stepanyan, S., Sokhan, D., Sober, D. I., Sparveris, N., Strauch, S., Taiuti, M., Tan, J. A., Ungaro, M., Voskanyan, H., Voutier, E., Watts, D. P., Weinstein, L., Wei, X., Weygand, D. P., Zachariou, N., Zhang, J., and Zhao, Z. W.
Published: 2018

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

Author: Fersch, R. G., Guler, N., Bosted, P., Deur, A., Griffioen, K., Keith, C., Kuhn, S. E., Minehart, R., Prok, Y., Adhikari, K. P., Adhikari, S., Akbar, Z., Amaryan, M. J., Anefalos Pereira, S., Asryan, G., Avakian, H., Ball, J., Balossino, I., Baltzell, N. A., Battaglieri, M., Bedlinskiy, I., Biselli, A. S., Briscoe, W. J., Brooks, W. K., Bültmann, S., Burkert, V. D., Thanh Cao, Frank, Carman, D. S., Careccia, S., Celentano, A., Chandavar, S., Charles, G., 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., De Sanctis, E., Djalali, C., Dodge, G. E., Dupre, R., Egiyan, H., El Alaoui, A., El Fassi, L., Elouadrhiri, L., Eugenio, P., Fanchini, E., Fedotov, G., Filippi, A., Fleming, J. A., Forest, T. A., Garçon, M., Gavalian, G., Ghandilyan, Y., Gilfoyle, G. P., Giovanetti, K. L., Girod, F. X., Gleason, C., Golovatch, E., Gothe, R. W., Guidal, M., Guo, L., Hafidi, K., Hakobyan, H., 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., Joo, K., Keller, D., Khachatryan, G., Khachatryan, M., Khandaker, M., Kim, A., Kim, W., Klein, A., Klein, F. J., Kubarovsky, V., Lagerquist, V. G., Lanza, L., Lenisa, P., Livingston, K., Lu, H. Y., McKinnon, B., Meyer, C. A., Mirazita, M., Mokeev, V., Montgomery, R. A., Movsisyan, A., Munoz Camacho, C., Murdoch, G., Nadel-Turonski, P., Niccolai, S., Niculescu, G., Niculescu, I., Osipenko, M., Ostrovidov, A. I., Paolone, M., Paremuzyan, R., Park, K., Pasyuk, E., Phelps, W., Pierce, J., Pisano, S., Pogorelko, O., Price, J. W., Protopopescu, D., Raue, B. A., Ripani, M., Riser, D., Rizzo, A., Rosner, G., Rossi, P., Roy, P., 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., 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., and Zhang, J.
Subjects: High Energy Physics::Experiment, Nuclear Experiment
Abstract: We present the results of our final analysis of the full data set of \ud g\ud p\ud 1\ud (\ud Q\ud 2\ud )\ud , the spin structure function of the proton, collected using CLAS at Jefferson Laboratory in 2000–2001. Polarized electrons with energies of 1.6, 2.5, 4.2, and 5.7 GeV were scattered from proton targets (\ud 15\ud NH\ud 3\ud dynamically polarized along the beam direction) and detected with CLAS. From the measured double spin asymmetries, we extracted virtual photon asymmetries \ud A\ud p\ud 1\ud and \ud A\ud p\ud 2\ud and spin structure functions \ud g\ud p\ud 1\ud and \ud g\ud p\ud 2\ud over a wide kinematic range (0.05 \ud GeV\ud 2\ud
Published: 2017

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

Author: Massachusetts Institute of Technology. Department of Physics, Massachusetts Institute of Technology. Laboratory for Nuclear Science, Hen, Or, Cruz Torres, Reynier, Beck, Sharon, Beck, Arie, Schmookler, Barak Abraham, Cohen, E. O., Piasetzky, E., Weinstein, L. B., Duer, M., Schmidt, A., Korover, I., Hakobyan, H., Adhikari, S., Akbar, Z., Amaryan, M. J., Avakian, H., Ball, J., Barion, L., Battaglieri, M., Bedlinskiy, I., Biselli, A. S., Boiarinov, S., Briscoe, W., Burkert, V. D., Cao, F., Carman, D. S., Celentano, A., Charles, G., Chatagnon, Pierre, Chetry, T., Ciullo, G., Clary, Brandon A., Contalbrigo, M., Crede, V., D’Angelo, A., Dashyan, N., De Vita, R., De Sanctis, E., Defurne, M., Deur, A., Diehl, S., Djalali, C., Dupre, R., Egiyan, H., Ehrhart, Mathieu, El Alaoui, A., Fassi, L. El, Eugenio, P., Fedotov, G., Fersch, R., Filippi, A., Ghandilyan, Y., Giovanetti, K. L., Girod, F. X., Golovatch, E., Gothe, R. W., Griffioen, K. A., Hafidi, K., Harrison, N., Hauenstein, F., Heddle, D., Hicks, K., Holtrop, M., 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., Klein, F. J., Kubarovsky, V., Kuhn, S. E., Lanza, L., Lenisa, P., Livingston, K., MacGregor, I. J. D., Marchand, D., McKinnon, B., Meyer, C. A., Mirazita, M., Mokeev, V., Montgomery, R. A., Movsisyan, A., Munoz Camacho, C., Mustapha, B., Nadel-Turonski, P., Niccolai, S., Niculescu, G., Osipenko, M., Ostrovidov, A. I., Paolone, M., Paremuzyan, R., Pasyuk, E., Pogorelko, O., Price, J. W., Prok, Y., Protopopescu, D., Ripani, M., Riser, D., Rizzo, A., Rosner, G., Rossi, P., Sabatié, F., Schumacher, R. A., Sharabian, Y. G., Sokhan, D., Sparveris, N., Stepanyan, S., Strauch, S., Taiuti, M., Tan, J. A., Ungaro, M., Voskanyan, H., Voutier, E., Wang, R., Watts, D. P., Wei, X., Wood, M. H., Zachariou, N., Zhang, J., Zheng, X., Zhao, Z. W., Massachusetts Institute of Technology. Department of Physics, Massachusetts Institute of Technology. Laboratory for Nuclear Science, Hen, Or, Cruz Torres, Reynier, Beck, Sharon, Beck, Arie, Schmookler, Barak Abraham, Cohen, E. O., Piasetzky, E., Weinstein, L. B., Duer, M., Schmidt, A., Korover, I., Hakobyan, H., Adhikari, S., Akbar, Z., Amaryan, M. J., Avakian, H., Ball, J., Barion, L., Battaglieri, M., Bedlinskiy, I., Biselli, A. S., Boiarinov, S., Briscoe, W., Burkert, V. D., Cao, F., Carman, D. S., Celentano, A., Charles, G., Chatagnon, Pierre, Chetry, T., Ciullo, G., Clary, Brandon A., Contalbrigo, M., Crede, V., D’Angelo, A., Dashyan, N., De Vita, R., De Sanctis, E., Defurne, M., Deur, A., Diehl, S., Djalali, C., Dupre, R., Egiyan, H., Ehrhart, Mathieu, El Alaoui, A., Fassi, L. El, Eugenio, P., Fedotov, G., Fersch, R., Filippi, A., Ghandilyan, Y., Giovanetti, K. L., Girod, F. X., Golovatch, E., Gothe, R. W., Griffioen, K. A., Hafidi, K., Harrison, N., Hauenstein, F., Heddle, D., Hicks, K., Holtrop, M., 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., Klein, F. J., Kubarovsky, V., Kuhn, S. E., Lanza, L., Lenisa, P., Livingston, K., MacGregor, I. J. D., Marchand, D., McKinnon, B., Meyer, C. A., Mirazita, M., Mokeev, V., Montgomery, R. A., Movsisyan, A., Munoz Camacho, C., Mustapha, B., Nadel-Turonski, P., Niccolai, S., Niculescu, G., Osipenko, M., Ostrovidov, A. I., Paolone, M., Paremuzyan, R., Pasyuk, E., Pogorelko, O., Price, J. W., Prok, Y., Protopopescu, D., Ripani, M., Riser, D., Rizzo, A., Rosner, G., Rossi, P., Sabatié, F., Schumacher, R. A., Sharabian, Y. G., Sokhan, D., Sparveris, N., Stepanyan, S., Strauch, S., Taiuti, M., Tan, J. A., Ungaro, M., Voskanyan, H., Voutier, E., Wang, R., Watts, D. P., Wei, X., Wood, M. H., Zachariou, N., Zhang, J., Zheng, X., and Zhao, Z. W.
Abstract: Short-range correlated (SRC) nucleon pairs are a vital part of the nucleus, accounting for almost all nucleons with momentum greater than the Fermi momentum (k[subscript F]). A fundamental characteristic of SRC pairs is having large relative momenta as compared to k[subscript F], and smaller center of mass (c.m.) which indicates a small separation distance between the nucleons in the pair. Determining the c.m. momentum distribution of SRC pairs is essential for understanding their formation process. We report here on the extraction of the c.m. motion of proton-proton (pp) SRC pairs in carbon and, for the first time in heavier and ansymetric nuclei: aluminum, iron, and lead, from measurements of the A(e,e′ pp) reaction. We find that the pair c.m. motion for these nuclei can be described by a three-dimensional Gaussian with a narrow width ranging from 140 to 170 MeV/c, approximately consistent with the sum of two mean-field nucleon momenta. Comparison with calculations appears to show that the SRC pairs are formed from mean-field nucleons in specific quantum states., National Science Foundation (U.S.)
Published: 2018

5. Target and beam-target spin asymmetries in exclusive pion electroproduction for Q2>1 GeV2. II. ep→eπ0p

Author: Bosted, P. E., Kim, A., Adhikari, K. P., Adikaram, D., Akbar, Z., Amaryan, M. J., Anefalos Pereira, S., 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., El Alaoui, A., El Fassi, L., 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., Munoz Camacho, C., 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 and High Energy Physics, Economica, Socio-culturale, High Energy Physics::Experiment, RESONANCE, Nuclear Experiment, Settore FIS/04 - Fisica Nucleare e Subnucleare
Abstract: Beam-target double-spin asymmetries and target single-spin asymmetries were measured for the exclusive \ud π\ud 0\ud electroproduction reaction \ud γ\ud ∗\ud p\ud →\ud p\ud π\ud 0\ud , expanding an analysis of the \ud γ\ud ∗\ud p\ud →\ud n\ud π\ud +\ud 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 Laboratory. The kinematic ranges covered are \ud 1.1\ud
Published: 2017

6. Measurement of target and double-spin asymmetries for the e p → eπ+(n) reaction in the nucleon resonance region at low Q2

Author: Zheng, X., Adhikari, K. P., Bosted, P., Deur, A., Drozdov, V., El Fassi, L., 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., Anefalos Pereira, S., 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., El Alaoui, A., 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., Munoz Camacho, C., 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., Zhang, J., and Zonta, I.
Subjects: Nuclear and High Energy Physics, Economica, Socio-culturale, High Energy Physics::Experiment, Nuclear Experiment, Settore FIS/04 - Fisica Nucleare e Subnucleare
Abstract: We report measurements of target- and double-spin asymmetries for the exclusive channel ep → eπ+(n) in\ud the nucleon resonance region at Jefferson Lab using the CEBAF Large Acceptance Spectrometer (CLAS). These\ud asymmetries were extracted from data obtained using a longitudinally polarized NH3 target and a longitudinally\ud polarized electron beam with energies 1.1, 1.3, 2.0, 2.3, and 3.0 GeV. The new results are consistent with previous\ud CLAS publications but are extended to a low Q2 range from 0.0065 to 0.35 (GeV/c)\ud 2. The Q2 access was made\ud possible by a custom-built Cherenkov detector that allowed the detection of electrons for scattering angles as low\ud as 6◦. These results are compared with the unitary isobar models JANR and MAID, the partial-wave analysis\ud prediction from SAID, and the dynamic model DMT. In many kinematic regions our results, in particular results\ud on the target asymmetry, help to constrain the polarization-dependent components of these models.
Published: 2016

7. Exclusive pi(0) electroproduction at W > 2 GeV with CLAS

Author: Bedlinskiy, I, Kubarovsky, V, Niccolai, S, Stoler, P, Adhikari, K, Anderson, M, Pereira, S, Avakian, H, Ball, J, Baltzell, N, Battaglieri, M, Batourine, V, Biselli, A, Boiarinov, S, Bono, J, Briscoe, W, Brooks, W, Burkert, V, Carman, D, Celentano, A, Chandavar, S, Colaneri, L, Cole, 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, El Alaoui, A, El Fassi, L, Elouadrhiri, L, Eugenio, P, Fedotov, G, Fegan, S, Fleming, J, Forest, T, Garillon, B, Garcon, M, Gavalian, G, Gevorgyan, N, Ghandilyan, Y, Gilfoyle, G, Giovanetti, K, Girod, F, Golovatch, E, Gothe, R, Griffioen, K, Guegan, B, Guidal, M, Guo, L, Hafidi, K, Hakobyan, H, Harrison, N, Hattawy, M, Hicks, K, Holtrop, M, Ireland, D, Ishkhanov, B, Isupov, E, Jenkins, D, Jo, H, Joo, K, Keller, D, Khandaker, M, Kim, A, Kim, W, Klein, A, Klein, F, Koirala, S, Kuhn, S, Kuleshov, S, Lenisa, P, Levine, W, Livingston, K, Lu, H, Macgregor, I, Markov, N, Mayer, M, Mckinnon, B, Mirazita, M, Mokeev, V, Montgomery, R, Moody, C, Moutarde, H, Movsisyan, A, Camacho, C, Nadel Turonski, P, Niculescu, I, Osipenko, M, Ostrovidov, A, Pappalardo, L, Park, K, Park, S, Pasyuk, E, Phelps, E, Phelps, W, Phillips, J, Pisano, S, Pogorelko, O, Price, J, Prok, Y, Protopopescu, D, Procureur, S, Puckett, A, Raue, B, Ripani, M, Ritchie, B, Rizzo, A, Rossi, P, Roy, P, Sabatie, F, Salgado, C, Schott, D, Schumacher, R, Seder, E, Senderovich, I, Sharabian, Y, Simonyan, A, Smith, G, Sober, D, Sokhan, D, Stepanyan, S, Strauch, S, Sytnik, V, Tang, W, Tian, Y, Ungaro, M, Vlassov, A, Voskanyan, H, Voutier, E, Walford, N, Watts, D, Wei, X, Weinstein, L, Yurov, M, Zachariou, N, Zana, L, Zhang, J, Zhao, Z, and Zonta, I
Subjects: TRANSVERSITY, PARTON DISTRIBUTIONS, PION ELECTROPRODUCTION, MESONS, SYSTEM, Settore FIS/04 - Fisica Nucleare e Subnucleare
Published: 2014

8. Comparison of forward and backward pp pair knockout in He-3(e,e'pp)n

Author: Baghdasaryan, H., Weinstein, L. B., Laget, J. M., Adhikari, K. P., Aghasyan, M., Amaryan, M. J., Anghinolfi, M., Ball, J., Battaglieri, M., Biselli, A. S., 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 Sanctis, E., De Vita, R., Djalali, C., Dodge, G. E., Doughty, D., Dupre, R., Egiyan, H., El Alaoui, A., El Fassi, L., Elouadrhiri, L., Fedotov, G., Gabrielyan, M. Y., Gevorgyan, N., Gilfoyle, G. P., Giovanetti, K. L., Girod, F. X., Gohn, W., Gothe, R. W., Griffioen, K. A., Guegan, B., Guidal, M., Hafidi, K., Hicks, K., Hyde, C. E., Ireland, D. G., Ishkhanov, B. S., Jenkins, D., Jo, H. S., Joo, K., Khandaker, M., Khetarpal, P., Kim, A., Kim, W., Kubarovsky, A., Kubarovsky, V., Kuhn, S. E., Kuleshov, S. V., Kvaltine, N. D., Lu, H. Y., MacGregor, I. J. D., McKinnon, B., Mirazita, M., Mokeev, V., Moutarde, H., Munevar, E., Niccolai, S., Niculescu, G., Niculescu, I., Osipenko, M., Paolone, M., Pappalardo, L. L., Paremuzyan, R., Park, K., Park, S., Pisano, S., Pozdniakov, S., Procureur, S., Raue, B. A., Ricco, G., Rimal, D., Ripani, M., Rosner, G., Rossi, P., Saini, M. S., Saylor, N. A., Schott, D., Schumacher, R. A., Seraydaryan, H., Smith, E. S., Sober, D. I., Sokan, D., Stepanyan, S. S., Stepanyan, S., Strauch, S., Taiuti, M., Tang, W., Tkachenko, S., Voskanyan, H., Voutier, E., Wood, M. H., Zana, L., and Zhao, B.
Subjects: MECHANISMS, DEUTERON, Settore FIS/04 - Fisica Nucleare e Subnucleare
Published: 2012

9. Measurement of the generalized form factors near threshold via gamma* p -> n pi(+) at high Q(2)

Author: Park, K., Gothe, R. W., Adhikari, K. P., Adikaram, D., Anghinolfi, M., Baghdasaryan, H., Ball, J., Battaglieri, M., Batourine, V., Bedlinskiy, I., Bennett, R. P., Biselli, A. S., Bookwalter, C., Boiarinov, S., Branford, D., Briscoe, W. J., Brooks, W. K., Burkert, V. D., Carman, D. S., Celentano, A., Chandavar, S., Charles, G., Cole, P. L., Contalbrigo, Marco, Crede, V., D'Angelo, A., Daniel, A., Dashyan, N., Vita, R. D., Sanctis, E. D., Deur, A., Djalali, C., Doughty, D., Dupre, R., Alaoui, A. E., Fassi, L. E., Eugenio, P., Fedotov, G., Fradi, A., Gabrielyan, M. Y., Gevorgyan, N., Gilfoyle, G. P., Giovanetti, K. L., Girod, F. X., Goetz, J. T., Gohn, W., Golovatch, E., Graham, L., Griffioen, K. A., Guidal, M., Guo, L., Hafidi, K., Hakobyan, H., Hanretty, C., Heddle, D., Hicks, K., Holtrop, M., Hyde, C. E., Ilieva, Y., Ireland, D. G., Ishkhanov, B. S., Isupov, E. L., Jenkins, D., H. S., Jo, Joo, K., Kalantarians, N., Khandaker, M., Khetarpal, P., Kim, A., Kim, W., Klein, A., Klein, F. J., Kubarovsky, A., Kubarovsky, V., Kuhn, S. E., Kuleshov, S. V., Kvaltine, N. D., Livingston, K., H. Y., Lu, I. J. D., Markov, N., Mayer, M., Mckinnon, B., Mestayer, M. D., Meyer, C. A., Mineeva, T., Mirazita, M., Mokeev, V., Moutarde, H., Munevar, E., Nadel Turonski, P., Nasseripour, R., Niccolai, S., Niculescu, G., Niculescu, I., Osipenko, M., Ostrovidov, A. I., Paolone, M., Pappalardo, Luciano Libero, Paremuzyan, R., Park, S., Pereira, S. A., Phelps, E., Pisano, S., Pogorelko, O., Pozdniakov, S., Price, J. W., Procureur, S., Prok, Y., 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., Strakovsky, I. I., Strauch, S., Taiuti, M., Tang, W., Taylor, C. E., Tian, Y., Tkachenko, S., Trivedi, A., Ungaro, M., Vernarsky, B., Vlassov, A. V., Voutier, E., Watts, D. P., Weygand, D. P., Wood, M. H., Zachariou, N., Zhao, B., and Zhao, Z. W.
Subjects: QUANTUM CHROMODYNAMICS, PI-0, PION ELECTROPRODUCTION, NUCLEONS, PROTON, PHOTOPRODUCTION, Settore FIS/04 - Fisica Nucleare e Subnucleare
Published: 2012

10. Exclusive Electron Scattering from Deuterium at High Momentum Transfer

Author: Bulten, H. J., Anthony, P. L., Arnold, R. G., Arrington, J., Beise, E. J., Belz, E., Van Bibber, K., Bosted, P. E., van den Brand, J. F. J., Chapman, M. S., Coulter, K. P., Dietrich, F. S., Ent, R., Epstein, M., Filippone, B. W., Gao, H., Gearhart, R. A., Geesaman, D. F., Hansen, J.-O., Holt, R. J., Jackson, H. E., Jones, C. E., Keppel, C. E., Kinney, E., Kuhn, S. E., Lee, K., Lorenzon, W., Lung, A., Makins, N. C. R., Margaziotis, D, J., McKeown, R. D., Milner, R. G., Mueller, B., Napolitano, J., Nelson, J., O'Neill, T. G., Papavassiliou, V., Petratos, G. G., Potterveld, D. H., Rock, S. E., Spengos, M., Szalata, Z. M., Tao, L. H., White, J. L., Zeidman, B., Bulten, H. J., Anthony, P. L., Arnold, R. G., Arrington, J., Beise, E. J., Belz, E., Van Bibber, K., Bosted, P. E., van den Brand, J. F. J., Chapman, M. S., Coulter, K. P., Dietrich, F. S., Ent, R., Epstein, M., Filippone, B. W., Gao, H., Gearhart, R. A., Geesaman, D. F., Hansen, J.-O., Holt, R. J., Jackson, H. E., Jones, C. E., Keppel, C. E., Kinney, E., Kuhn, S. E., Lee, K., Lorenzon, W., Lung, A., Makins, N. C. R., Margaziotis, D, J., McKeown, R. D., Milner, R. G., Mueller, B., Napolitano, J., Nelson, J., O'Neill, T. G., Papavassiliou, V., Petratos, G. G., Potterveld, D. H., Rock, S. E., Spengos, M., Szalata, Z. M., Tao, L. H., White, J. L., and Zeidman, B.
Abstract: Cross sections are presented for the reaction 2H(e,e′p)n for momentum transfers in the range 1.2≤Q^2≤6.8 (GeV/c)^2 and for missing momenta from 0 to 250 MeV/c. The longitudinal-transverse interference structure function has been separated at Q^2 = 1.2 (GeV/c)^2. The observables are compared to calculations performed in nonrelativistic and relativistic frameworks. The data are best described by a fully relativistic calculation.
Published: 1995

11. Anisotropy and multiband superconductivity in Sr2RuO4 determined by small-angle neutron scattering studies of the vortex lattice.

Author: Kuhn, S. J., Morgenlander, W., Louden, E. R., Rastovski, C., Gannon, W. J., Takatsu, H., Peets, D. C., Maeno, Y., Dewhurst, C. D., Gavilano, J., and Eskildsen, M. R.
Subjects: *SUPERCONDUCTORS, *STRONTIUM compounds, *NEUTRON scattering
Abstract: espite numerous studies the exact nature of the order parameter in superconducting Sr2RuO4 remains unresolved. We have extended previous small-angle neutron scattering studies of the vortex lattice in this material to a wider field range, higher temperatures, and with the field applied close to both the ⟨100⟩ and ⟨110⟩ basal plane directions. Measurements at high field were made possible by the use of both spin polarization and analysis to improve the signal-to-noise ratio. Rotating the field towards the basal plane causes a distortion of the square vortex lattice observed for H∥⟨001⟩ and also a symmetry change to a distorted triangular symmetry for fields close to ⟨100⟩.The vortex lattice distortion allows us to determine the intrinsic superconducting anisotropy between the c axis and the Ru-O basal plane, yielding a value of ∼60 at low temperature and low to intermediate fields. This greatly exceeds the upper critical field anisotropy of ∼20 at low temperature, reminiscent of Pauli limiting. Indirect evidence for Pauli paramagnetic effects on the unpaired quasiparticles in the vortex cores are observed, but a direct detection lies below the measurement sensitivity. The superconducting anisotropy is found to be independent of temperature but increases for fields ≳1 T, indicating multiband superconductvity in Sr2RuO4. Finally, the temperature dependence of the scattered intensity provides further support for gap nodes or deep minima in the superconducting gap. [ABSTRACT FROM AUTHOR]
Published: 2017
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12. Simultaneous evidence for Pauli paramagnetic effects and multiband superconductivity in KFe2As2 by small-angle neutron scattering studies of the vortex lattice.

Author: Kuhn, S. J., Kawano-Furukawa, H., Jellyman, E., Riyat, R., Forgan, E. M., Ono, M., Kihou, K., Lee, C. H., Hardy, F., Adelmann, P., Wolf, Th., Meingast, C., Gavilano, J., and Eskildsen, M. R.
Subjects: *POTASSIUM compounds, *SMALL-angle neutron scattering, *SUPERCONDUCTIVITY
Abstract: We study the intrinsic anisotropy of the superconducting state in KFe2As2 by using small-angle neutron scattering to image the vortex lattice as the applied magnetic field is rotated towards the FeAs crystalline planes. The anisotropy is found to be strongly field dependent, indicating multiband superconductivity. Furthermore, the high-field anisotropy significantly exceeds that of the upper critical field, providing further support for Pauli limiting in KFe2As2 for fields applied in the basal plane. The effect of Pauli paramagnetism on the unpaired quasiparticles in the vortex cores is directly evident from the ratio of scattered intensities due to the longitudinal and transverse vortex lattice field modulation. [ABSTRACT FROM AUTHOR]
Published: 2016
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13. Precise determination of the deuteron spin structure at low to moderate Q² 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., Anefalos Pereira, S., Avakian, H., Ball, J., Battaglieri, M., Batourine, V., Bedlinskiy, I., Biselli, A., and Briscoe, W. J.
Subjects: *NEUTRON spin, *ELECTRON beam research, *DEUTERON scattering, *POLARIZED electrons, *SPECTROMETERS
Abstract: We present the final results for the deuteron spin structure functions obtained from the full data set collected in 2000-2001 with Jefferson Lab's continuous electron beam accelerator facility (CEBAF) using the CEBAF large acceptance spectrometer (CLAS). Polarized electrons with energies of 1.6, 2.5, 4.2, and 5.8 GeV were scattered from deuteron (I5ND3) targets, dynamically polarized along the beam direction, and detected with CLAS. From the measured double-spin asymmetry, the virtual photon absorption asymmetry A1d and the polarized structure function g1d were extracted over a wide kinematic range (0.05 GeV² < Q² < 5 GeV² 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 A1n and g1n 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. [ABSTRACT FROM AUTHOR]
Published: 2015
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14. Measurement of the EMC effect in the deuteron.

Author: Griffioen, K. A., Arrington, J., Christy, M. E., Ent, R., Kalantarians, N., Keppel, C. E., Kuhn, S. E., Melnitchouk, W., Niculescu, G., Niculescu, I., Tkachenko, S., and Zhang, J.
Subjects: *ELECTROMAGNETIC compatibility, *DEUTERONS, *NUCLEAR physics, *MATHEMATICAL functions, *ACQUISITION of data, *EMPIRICAL research
Abstract: We determined the structure function ratio REMCd = F2d/(F2n+F2p) from recently published F2n/F2d data taken by the BONuS experiment using CLAS at Jefferson Lab. This ratio deviates from unity, with a slope dREMCd/dx= -0.10 ± 0.05 in the range of Bjorken x from 0.35 to 0.7, for invariant mass W>1.4 GeV and Q² > 1GeV². The observed EMC effect for these kinematics is consistent with conventional nuclear physics models that include off-shell corrections, as well as with empirical analyses that find the EMC effect proportional to the probability of short-range nucleon-nucleon correlations. [ABSTRACT FROM AUTHOR]
Published: 2015
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15. Direct observation of quark-hadron duality in the free neutron F2 structure function.

Author: Niculescu, I., Niculescu, G., Melnitchouk, W., Arrington, J., Christy, M. E., Ent, R., Griffioen, K. A., Kalantarians, N., Keppel, C. E., Kuhn, S., Tkachenko, S., and Zhang, J.
Subjects: *QUARK-hadron interactions, *NEUTRON scattering, *PARTICLES (Nuclear physics), *NUCLEAR cross sections, *PARTONS
Abstract: Using the recently published data from the BONuS (Barely Off-shell Nucleon Structure) experiment at Jefferson Lab, which utilized a spectator tagging technique to extract the inclusive electron-free neutron scattering cross section, we obtain the first direct observation of quark-hadron duality in the neutron F2 structure function. The data are used to reconstruct the lowest few (N=2, 4, and 6) moments of F2 in the three prominent nucleon resonance regions, as well as the moments integrated over the entire resonance region. Comparison with moments computed from global parametrizations of parton distribution functions suggest that quark-hadron duality holds locally for the neutron in the second and third resonance regions down to Q² ≈ 1 GeV², with violations possibly up to 20% observed in the first resonance region. [ABSTRACT FROM AUTHOR]
Published: 2015
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16. Competing single-particle and collective behavior in 71Se.

Author: Howe, A. R., Haring-Kaye, R. A., Döring, J., Baker, N. R., Kuhn, S. J., Tabor, S. L., Arora, S. R., Bruckman, J. K., and Hoffman, C. R.
Subjects: *SELENIUM, *NUCLEAR reactions, *CRYSTAL detectors, *CRYSTAL sets (Radio), *RADIO rectifiers
Abstract: The high-spin decay of 71Se was studied using the 54Fe(23Na,αpn) reaction at 80 MeV and the Florida State University Compton-suppressed Ge array consisting of three clover detectors and seven single-crystal detectors. Based on prompt γ-γ coincidences measured in the experiment, the known level scheme was enhanced and extended to higher spin with 19 new transitions. A band that was previously suggested to have positive parity was reassigned as the "missing" signature partner of an existing negative-parity band. Spins were assigned based on directional correlation of oriented nuclei ratios. Lifetimes of 17 excited states were measured using the Doppler-shift attenuation method. Experimental Qt values imply an intermediate degree of collective behavior for 71Se at high spin. Theoretical Qt values determined from cranked Woods-Saxon (CWS) calculations show better agreement with the experimental ones for the positive-parity states than the negative-parity states. Shape competition and γ softness characterize the low-spin states of the lowest positive- and negative-parity bands based on the CWS calculations. At high spin, triaxial shapes with γ > 0° are predicted. [ABSTRACT FROM AUTHOR]
Published: 2012
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17. High precision determination of the Q² evolution of the Bjorken sum.

Author: Deur, A., Prok, Y., Burkert, V., Crabb, D., Girod, F.-X., Griffioen, K. A., Guler, N., Kuhn, S. E., and Kvaltine, N.
Subjects: *DEEP inelastic collisions, *HADRON interactions, *ELEMENTARY particle scattering, *PARTICLE physics, *NUCLEAR structure, *NUCLEAR reactions
Abstract: We present a significantly improved determination of the Bjorken sum for 0.6 ≤ Q² ≤ 4.8 GeV² using precise new g1pand g1d data taken with the CLAS detector at Jefferson Lab. A higher-twist analysis of the Q² dependence of the Bjorken sum yields the twist-4 coefficient = -0.064 ± ... This leads to the color polarizabilities ep-n = -0.032 ± 0.024 and Bp-n = 0.032 ± 0.013. The strong force coupling is determined to be αsMS = 0.1123 ± 0.0061, which has an uncertainty a factor of 1.5 smaller than earlier estimates using polarized deep inelastic scattering (DIS) data. This improvement makes the comparison between as extracted from polarized DIS and other techniques a valuable test of QCD. [ABSTRACT FROM AUTHOR]
Published: 2014
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18. First Measurement of Hard Exclusive π^{-}Δ^{++} Electroproduction Beam-Spin Asymmetries off the Proton.

Author: Diehl S, Trotta N, Joo K, Achenbach P, Akbar Z, Armstrong WR, Atac H, Avakian H, Baashen L, Baltzell NA, Barion L, Bashkanov M, Battaglieri M, Bedlinskiy I, Benmokhtar F, Bianconi A, Biselli AS, Bossù F, Brinkmann KT, Briscoe WJ, Bulumulla D, Burkert V, Capobianco R, Carman DS, Carvajal JC, Celentano A, Charles G, Chatagnon P, Chesnokov V, Ciullo G, Cole PL, Contalbrigo M, Costantini G, Crede V, D'Angelo A, Dashyan N, De Vita R, Deur A, Djalali C, Dupre R, Ehrhart M, El Alaoui A, El Fassi L, Elouadrhiri L, Fegan S, Filippi A, Gavalian G, Glazier DI, Golubenko AA, Gosta G, Gothe RW, Gotra Y, Griffioen K, Hafidi K, Hakobyan H, Hattawy M, Hayward TB, Heddle D, Hobart A, Holtrop M, Illari I, Ireland DG, Isupov EL, Jo HS, Johnston R, Keller D, Khachatryan M, Khanal A, Kim A, Kim W, Klimenko V, Kripko A, Kubarovsky V, Kuhn SE, Lagerquist V, Lanza L, Leali M, Lee S, Lenisa P, Li X, MacGregor IJD, Marchand D, Mascagna V, Matousek G, McKinnon B, McLauchlin C, Meziani ZE, Migliorati S, Milner RG, Mineeva T, Mirazita M, Mokeev V, Moran P, Munoz Camacho C, Naidoo P, Neupane K, Niccolai S, Niculescu G, Osipenko M, Pandey P, Paolone M, Pappalardo LL, Paremuzyan R, Paul SJ, Phelps W, Pilleux N, Pokhrel M, Poudel J, Price JW, Prok Y, Radic A, Raue BA, Reed T, Richards J, Ripani M, Ritman J, Rossi P, Sabatié F, Salgado C, Schadmand S, Schmidt A, Sharabian YG, Shrestha U, Sokhan D, Sparveris N, Spreafico M, Stepanyan S, Strakovsky I, Strauch S, Turisini M, Tyson R, Ungaro M, Vallarino S, Venturelli L, Voskanyan H, Voutier E, Watts DP, Wei X, Williams R, Wishart R, Wood MH, Yurov M, Zachariou N, Zhao ZW, and Zurek M
Abstract: The polarized cross-section ratio σ_{LT^{'}}/σ_{0} from hard exclusive π^{-}Δ^{++} electroproduction off an unpolarized hydrogen target has been extracted based on beam-spin asymmetry measurements using a 10.2 GeV/10.6 GeV incident electron beam and the CLAS12 spectrometer at Jefferson Lab. The study, which provides the first observation of this channel in the deep-inelastic regime, focuses on very forward-pion kinematics in the valence regime, and photon virtualities ranging from 1.5 GeV^{2} up to 7 GeV^{2}. The reaction provides a novel access to the d-quark content of the nucleon and to p→Δ^{++} transition generalized parton distributions. A comparison to existing results for hard exclusive π^{+}n and π^{0}p electroproduction is provided, which shows a clear impact of the excitation mechanism, encoded in transition generalized parton distributions, on the asymmetry.
Published: 2023
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19. First CLAS12 Measurement of Deeply Virtual Compton Scattering Beam-Spin Asymmetries in the Extended Valence Region.

Author: Christiaens G, Defurne M, Sokhan D, Achenbach P, Akbar Z, Amaryan MJ, Atac H, Avakian H, Gayoso CA, Baashen L, Baltzell NA, Barion L, Bashkanov M, Battaglieri M, Bedlinskiy I, Benkel B, Benmokhtar F, Bianconi A, Biselli AS, Bondi M, Booth WA, Bossù F, Boiarinov S, Brinkmann KT, Briscoe WJ, Bueltmann S, Bulumulla D, Burkert VD, Cao T, Carman DS, Carvajal JC, Celentano A, Chatagnon P, Chesnokov V, Chetry T, Ciullo G, Clash G, Cole PL, Contalbrigo M, Costantini G, D'Angelo A, Dashyan N, De Vita R, Deur A, Diehl S, Dilks C, Djalali C, Dupre R, Egiyan H, Ehrhart M, Alaoui AE, Fassi LE, Elouadrhiri L, Fegan S, Filippi A, Gates K, Gavalian G, Ghandilyan Y, Gilfoyle GP, Girod FX, Glazier DI, Golubenko AA, Gosta G, Gothe RW, Gotra Y, Griffioen KA, Guidal M, Hafidi K, Hakobyan H, Hattawy M, Hauenstein F, Hayward TB, Heddle D, Hobart A, Holmberg DE, Holtrop M, Ilieva Y, Ireland DG, Isupov EL, Jo HS, Keller D, Khachatryan M, Khanal A, Kim W, Kripko A, Kubarovsky V, Kuhn SE, Lagerquist V, Lanza L, Kabir ML, Leali M, Lee S, Lenisa P, Li X, Livingston K, MacGregor IJD, Marchand D, Mascagna V, Matousek G, McKinnon B, McLauchlin C, Meziani ZE, Migliorati S, Milner RG, Mineeva T, Mirazita M, Mokeev V, Molina E, Camacho CM, Nadel-Turonski P, Naidoo P, Neupane K, Niccolai S, Nicol M, Niculescu G, Osipenko M, Ouillon M, Pandey P, Paolone M, Pappalardo LL, Paremuzyan R, Pasyuk E, Paul SJ, Phelps W, Pilleux N, Pokhrel M, Poudel J, Price JW, Prok Y, Radic A, Ramasubramanian N, Raue BA, Reed T, Richards J, Ripani M, Ritman J, Rossi P, Sabatié F, Salgado C, Schadmand S, Schmidt A, Scott MBC, Sharabian YG, Shirokov EV, Shrestha U, Simmerling P, Sparveris N, Spreafico M, Stepanyan S, Strakovsky II, Strauch S, Tan JA, Trotta N, Turisini M, Tyson R, Ungaro M, Vallarino S, Venturelli L, Voskanyan H, Voutier E, Watts DP, Wei X, Williams R, Wishart R, Wood MH, Zachariou N, Zhang J, Zhao ZW, Ziegler V, and Zurek M
Abstract: Deeply virtual Compton scattering (DVCS) allows one to probe generalized parton distributions describing the 3D structure of the nucleon. We report the first measurement of the DVCS beam-spin asymmetry using the CLAS12 spectrometer with a 10.2 and 10.6 GeV electron beam scattering from unpolarized protons. The results greatly extend the Q^{2} and Bjorken-x phase space beyond the existing data in the valence region and provide 1600 new data points measured with unprecedented statistical uncertainty, setting new, tight constraints for future phenomenological studies.
Published: 2023
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20. Observation of Correlations between Spin and Transverse Momenta in Back-to-Back Dihadron Production at CLAS12.

Author: Avakian H, Hayward TB, Kotzinian A, Armstrong WR, Atac H, Ayerbe Gayoso C, Baashen L, Baltzell NA, Barion L, Bashkanov M, Battaglieri M, Bedlinskiy I, Benkel B, Benmokhtar F, Bianconi A, Biondo L, Biselli AS, Bondi M, Boiarinov S, Bossù F, Brinkman KT, Briscoe WJ, Brooks WK, Bueltmann S, Bulumulla D, Burkert VD, Capobianco R, Carman DS, Carvajal JC, Celentano A, Chatagnon P, Chesnokov V, Chetry T, Ciullo G, Cole PL, Contalbrigo M, Costantini G, D'Angelo A, Dashyan N, De Vita R, Defurne M, Deur A, Diehl S, Dilks C, Djalali C, Dupre R, Egiyan H, El Alaoui A, El Fassi L, Elouadrhiri L, Fegan S, Filippi A, Forest T, Gates K, Gavalian G, Ghandilyan Y, Glazier DI, Golubenko AA, Gosta G, Gothe RW, Gotra Y, Griffioen KA, Guidal M, Hakobyan H, Hattawy M, Hauenstein F, Heddle D, Hobart A, Holtrop M, Hyde CE, Ilieva Y, Ireland DG, Isupov EL, Jo HS, Johnston R, Joo K, Kabir ML, Keller D, Khachatryan M, Khanal A, Kim A, Kim W, Klimenko V, Kripko A, Kubarovsky V, Kuhn SE, Lagerquist V, Lanza L, Leali M, Lee S, Lenisa P, Li X, MacGregor IJD, Marchand D, Mascagna V, McKinnon B, Migliorati S, Mineeva T, Mirazita M, Mokeev V, Montgomery RA, Munoz Camacho C, Nadel-Turonski P, Naidoo P, Neupane K, Nguyen D, Niccolai S, Nicol M, Niculescu G, Osipenko M, Pandey P, Paolone M, Pappalardo LL, Paremuzyan R, Pasyuk E, Paul SJ, Phelps W, Pilleux N, Pogorelko O, Pokhrel M, Poudel J, Price JW, Prok Y, Raue BA, Reed T, Richards J, Ripani M, Ritman J, Rossi P, Sabatié F, Salgado C, Schmidt A, Sharabian YG, Shirokov EV, Shrestha U, Simmerling P, Sokhan D, Sparveris N, Stepanyan S, Strakovsky II, Strauch S, Tan JA, Trotta N, Tyson R, Ungaro M, Vallarino S, Venturelli L, Voskanyan H, Vossen A, Voutier E, Watts DP, Wei X, Wishart R, Wood MH, Zachariou N, Zhao ZW, and Zurek M
Abstract: We report the first measurements of deep inelastic scattering spin-dependent azimuthal asymmetries in back-to-back dihadron electroproduction in the deep inelastic scattering process. In this reaction, two hadrons are produced in opposite hemispheres along the z axis in the virtual photon-target nucleon center-of-mass frame, with the first hadron produced in the current-fragmentation region and the second in the target-fragmentation region. The data were taken with longitudinally polarized electron beams of 10.2 and 10.6 GeV incident on an unpolarized liquid-hydrogen target using the CLAS12 spectrometer at Jefferson Lab. Observed nonzero sinΔϕ modulations in ep→e^{'}pπ^{+}X events, where Δϕ is the difference of the azimuthal angles of the proton and pion in the virtual photon and target nucleon center-of-mass frame, indicate that correlations between the spin and transverse momenta of hadrons produced in the target- and current-fragmentation regions may be significant. The measured beam-spin asymmetries provide a first access in dihadron production to a previously unexplored leading-twist spin- and transverse-momentum-dependent fracture function. The fracture functions describe the hadronization of the target remnant after the hard scattering of a virtual photon off a quark in the target particle and provide a new avenue for studying nucleonic structure and hadronization.
Published: 2023
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21. Multidimensional, High Precision Measurements of Beam Single Spin Asymmetries in Semi-inclusive π^{+} Electroproduction off Protons in the Valence Region.

Author: Diehl S, Kim A, Angelini G, Joo K, Adhikari S, Amaryan M, Arratia M, Atac H, Avakian H, Ayerbe Gayoso C, Baltzell NA, Barion L, Bastami S, Battaglieri M, Bedlinskiy I, Benmokhtar F, Bianconi A, Biselli AS, Bondi M, Bossù F, Boiarinov S, Brinkmann KT, Briscoe WJ, Brooks W, Bulumulla D, Burkert VD, Carman DS, Carvajal JC, Celentano A, Chatagnon P, Chetry T, Ciullo G, Clark L, Clary BA, Cole PL, Contalbrigo M, Costantini G, Crede V, D'Angelo A, Dashyan N, De Vita R, Defurne M, Deur A, Dilks C, Djalali C, Dugger M, Dupre R, Egiyan H, Ehrhart M, El Alaoui A, El Fassi L, Elouadrhiri L, Fegan S, Filippi A, Forest T, Gavalian G, Gilfoyle GP, Girod FX, Glazier DI, Golubenko AA, Gothe RW, Gotra Y, Griffioen KA, Guidal M, Hafidi K, Hakobyan H, Hattawy M, Hauenstein F, Hayward TB, Heddle D, Hicks K, Hobart A, Holtrop M, Hyde CE, Ireland DG, Isupov EL, Jo HS, Johnston R, Joosten S, Keller D, Khachatryan M, Khanal A, Kim W, Kripko A, Kubarovsky V, Kuhn SE, Lanza L, Leali M, Lee S, Lenisa P, Livingston K, Lu Z, MacGregor IJD, Marchand D, Markov N, Marsicano L, Mascagna V, McKinnon B, Meziani ZE, Milner RG, Mineeva T, Mirazita M, Mokeev V, Moran P, Movsisyan A, Munoz Camacho C, Nadel-Turonski P, Naidoo P, Nanda S, Neupane K, Niccolai S, Niculescu G, O'Connell TR, Osipenko M, Paolone M, Pappalardo LL, Paremuzyan R, Pasyuk E, Phelps W, Pogorelko O, Prok Y, Prokudin A, Raue BA, Ripani M, Ritman J, Rizzo A, Roberts CD, Rossi P, Rowley J, Sabatié F, Salgado C, Schmidt A, Segarra EP, Sharabian YG, Shrestha U, Simmerling P, Sokhan D, Soto O, Sparveris N, Stepanyan S, Stoler P, Strakovsky II, Strauch S, Tezgin K, Thornton A, Tyler N, Tyson R, Ungaro M, Venturelli L, Voskanyan H, Vossen A, Voutier E, Watts DP, Wei K, Wei X, Xu SS, Yale B, Zachariou N, and Zhang J
Abstract: High precision measurements of the polarized electron beam-spin asymmetry in semi-inclusive deep inelastic scattering (SIDIS) from the proton have been performed using a 10.6 GeV incident electron beam and the CLAS12 spectrometer at Jefferson Lab. We report here a high precision multidimensional study of single π^{+} SIDIS data over a large kinematic range in Bjorken x, fractional energy, and transverse momentum of the hadron as well as photon virtualities Q^{2} ranging from 1-7 GeV^{2}. In particular, the structure function ratio F_{LU}^{sinϕ}/F_{UU} has been determined, where F_{LU}^{sinϕ} is a twist-3 quantity that can reveal novel aspects of emergent hadron mass and quark-gluon correlations within the nucleon. The data's impact on the evolving understanding of the underlying reaction mechanisms and their kinematic variation is explored using theoretical models for the different contributing transverse momentum dependent parton distribution functions.
Published: 2022
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22. Improved Λp Elastic Scattering Cross Sections between 0.9 and 2.0 GeV/c as a Main Ingredient of the Neutron Star Equation of State.

Author: Rowley J, Compton N, Djalali C, Hicks K, Price J, Zachariou N, Adhikari KP, Armstrong WR, Atac H, Baashen L, Barion L, Bashkanov M, Battaglieri M, Bedlinskiy I, Benmokhtar F, Bianconi A, Biondo L, Biselli AS, Bondi M, Bossù F, Boiarinov S, Briscoe WJ, Brooks WK, Bulumulla D, Burkert VD, Carman DS, Carvajal JC, Celentano A, Chatagnon P, Chesnokov V, Chetry T, Ciullo G, Clark L, Cole PL, Contalbrigo M, Costantini G, Crede V, D'Angelo A, Dashyan N, De Vita R, Defurne M, Deur A, Diehl S, Dupré R, Egiyan H, Ehrhart M, El Alaoui A, El Fassi L, Eugenio P, Fedotov G, Fegan S, Fersch R, Filippi A, Fradi A, Gavalian G, Girod FX, Glazier DI, Golubenko A, Gothe RW, Griffioen K, Guo L, Hafidi K, Hakobyan H, Hattawy M, Hayward TB, Heddle D, Hobart A, Holtrop M, Ilieva Y, Ireland DG, Isupov EL, Jenkins D, Jo HS, Joo K, Keller D, Khanal A, Khandaker M, Kim A, Korover I, Kripko A, Kubarovsky V, Kuhn SE, Lanza L, Leali M, Lenisa P, Livingston K, MacGregor IJD, Marchand D, Markov N, Marsicano L, Mascagna V, McCracken ME, McKinnon B, McLauchlin C, Meziani ZE, Migliorati S, Mineeva T, Mirazita M, Mokeev V, Munevar E, Munoz Camacho C, Nadel-Turonski P, Neupane K, Niccolai S, Niculescu G, O'Connell TR, Osipenko M, Ostrovidov AI, Pandey P, Paolone M, Pappalardo LL, Pasyuk E, Pogorelko O, Prok Y, Reed T, Ripani M, Ritman J, Rizzo A, Rosner G, Sabatie F, Salgado C, Schmidt A, Schumacher RA, Sharabian YG, Shrestha U, Sokhan D, Soto O, Sparveris N, Strakovsky II, Strauch S, Tyson R, Ungaro M, Venturelli L, Voskanyan H, Vossen A, Voutier E, Watts DP, Wei K, Wei X, Wishart R, Wood MH, Yale B, Yurov M, Zhang J, and Zhao ZW
Abstract: Strange matter is believed to exist in the cores of neutron stars based on simple kinematics. If this is true, then hyperon-nucleon interactions will play a significant part in the neutron star equation of state. Yet, compared to other elastic scattering processes, there is very little data on Λ-N scattering. This experiment utilized the CEBAF Large Acceptance Spectrometer (CLAS) detector to study the Λp→Λp elastic scattering cross section in the incident Λ momentum range 0.9-2.0 GeV/c. These are the first data on this reaction since the 1970s. The new cross sections have significantly better accuracy and precision than the existing world data, and the techniques developed here can also be used in future experiments.
Published: 2021
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23. First Measurement of Timelike Compton Scattering.

Author: Chatagnon P, Niccolai S, Stepanyan S, Amaryan MJ, Angelini G, Armstrong WR, Atac H, Ayerbe Gayoso C, Baltzell NA, Barion L, Bashkanov M, Battaglieri M, Bedlinskiy I, Benmokhtar F, Bianconi A, Biondo L, Biselli AS, Bondi M, Bossù F, Boiarinov S, Briscoe WJ, Brooks WK, Bulumulla D, Burkert VD, Carman DS, Carvajal JC, Caudron M, Celentano A, Chetry T, Ciullo G, Clark L, Cole PL, Contalbrigo M, Costantini G, Crede V, D'Angelo A, Dashyan N, Defurne M, De Vita R, Deur A, Diehl S, Djalali C, Dupré R, Egiyan H, Ehrhart M, El Alaoui A, El Fassi L, Elouadrhiri L, Fegan S, Fersch R, Filippi A, Gavalian G, Ghandilyan Y, Gilfoyle GP, Girod FX, Glazier DI, Golubenko AA, Gothe RW, Gotra Y, Griffioen KA, Guidal M, Guo L, Hakobyan H, Hattawy M, Hayward TB, Heddle D, Hobart A, Holtrop M, Hyde CE, Ilieva Y, Ireland DG, Isupov EL, Jo HS, Joo K, Kabir ML, Keller D, Khachatryan G, Khanal A, Kim A, Kim W, Kripko A, Kubarovsky V, Kuhn SE, Lanza L, Leali M, Lee S, Lenisa P, Livingston K, MacGregor IJD, Marchand D, Marsicano L, Mascagna V, McKinnon B, McLauchlin C, Migliorati S, Mirazita M, Mokeev V, Montgomery RA, Munoz Camacho C, Nadel-Turonski P, Naidoo P, Neupane K, O'Connell TR, Osipenko M, Ouillon M, Pandey P, Paolone M, Pappalardo LL, Paremuzyan R, Pasyuk E, Phelps W, Pogorelko O, Poudel J, Price JW, Prok Y, Raue BA, Reed T, Ripani M, Rizzo A, Rossi P, Rowley J, Sabatié F, Schmidt A, Segarra EP, Sharabian YG, Shirokov EV, Shrestha U, Sokhan D, Soto O, Sparveris N, Strakovsky II, Strauch S, Tyler N, Tyson R, Ungaro M, Vallarino S, Venturelli L, Voskanyan H, Vossen A, Voutier E, Watts DP, Wei K, Wei X, Wishart R, Yale B, Zachariou N, Zhang J, and Zhao ZW
Abstract: We present the first measurement of the timelike Compton scattering process, γp→p^{'}γ^{*}(γ^{*}→e^{+}e^{-}), obtained with the CLAS12 detector at Jefferson Lab. The photon beam polarization and the decay lepton angular asymmetries are reported in the range of timelike photon virtualities 2.25
Published: 2021
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24. Observation of Beam Spin Asymmetries in the Process ep→e^{'}π^{+}π^{-}X with CLAS12.

Author: Hayward TB, Dilks C, Vossen A, Avakian H, Adhikari S, Angelini G, Arratia M, Atac H, Ayerbe Gayoso C, Baltzell NA, Barion L, Battaglieri M, Bedlinskiy I, Benmokhtar F, Bianconi A, Biselli AS, Bondì M, Bossù F, Boiarinov S, Briscoe WJ, Brooks WK, Bulumulla D, Burkert VD, Carman DS, Carvajal JC, Celentano A, Chatagnon P, Chetry T, Ciullo G, Clary BA, Cole PL, Contalbrigo M, Costantini G, Crede V, D'Angelo A, Dashyan N, De Vita R, Defurne M, Deur A, Diehl S, Djalali C, Dupre R, Dugger M, Egiyan H, Ehrhart M, El Alaoui A, El Fassi L, Elouadrhiri L, Fegan S, Filippi A, Forest TA, Gavalian G, Gilfoyle GP, Girod FX, Glazier DI, Golubenko AA, Gothe RW, Gotra Y, Griffioen KA, Guidal M, Hafidi K, Hakobyan H, Hattawy M, Hauenstein F, Hicks K, Hobart A, Holtrop M, Ireland DG, Isupov EL, Jo HS, Joo K, Joosten S, Keller D, Khachatryan M, Khanal A, Kim A, Kim W, Kripko A, Kubarovsky V, Kuhn SE, Lanza L, Leali M, Lee S, Lenisa P, Livingston K, MacGregor IJD, Marchand D, Markov N, Marsicano L, Mascagna V, McKinnon B, Meziani ZE, Mirazita M, Mokeev V, Movsisyan A, Munoz Camacho C, Nadel-Turonski P, Naidoo P, Nanda S, Neupane K, Niccolai S, Niculescu G, O'Connell TR, Osipenko M, Paolone M, Pappalardo LL, Paremuzyan R, Pasyuk E, Phelps W, Pogorelko O, Prok Y, Raue BA, Ripani M, Ritman J, Rizzo A, Rossi P, Rowley J, Sabatié F, Salgado C, Schmidt A, Segarra EP, Sharabian YG, Shrestha U, Sokhan D, Soto O, Sparveris N, Stepanyan S, Strakovsky II, Strauch S, Thornton A, Tyler N, Tyson R, Ungaro M, Venturelli L, Voskanyan H, Voutier E, Watts DP, Wei K, Wei X, Wood MH, Yale B, Zachariou N, and Zhang J
Abstract: The observation of beam spin asymmetries in two-pion production in semi-inclusive deep inelastic scattering off an unpolarized proton target is reported. The data presented here were taken in the fall of 2018 with the CLAS12 spectrometer using a 10.6 GeV longitudinally spin-polarized electron beam delivered by CEBAF at JLab. The measured asymmetries provide the first opportunity to extract the parton distribution function e(x), which provides information about the interaction between gluons and quarks, in a collinear framework that offers cleaner access than previous measurements. The asymmetries also constitute the first ever signal sensitive to the helicity-dependent two-pion fragmentation function G_{1}^{⊥}. A clear sign change is observed around the ρ mass that appears in model calculations and is indicative of the dependence of the produced pions on the helicity of the fragmenting quark.
Published: 2021
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25. Beam Spin Asymmetry in Semi-Inclusive Electroproduction of Hadron Pairs.

Author: Mirazita M, Avakian H, Courtoy A, Pisano S, Adhikari S, Amaryan MJ, Angelini G, Atac H, Baltzell NA, Barion L, Battaglieri M, Bedlinskiy I, Benmokhtar F, Bianconi A, Biselli AS, Bossù F, Boiarinov S, Briscoe WJ, Brooks WK, Bulumulla D, Burkert VD, Carman DS, Carvajal JC, Celentano A, Chatagnon P, Chetry T, Ciullo G, Clary B, Cole PL, Contalbrigo M, Crede V, D'Angelo A, Dashyan N, De Vita R, Defurne M, Deur A, Diehl S, Dilks C, Djalali C, Dupre R, Egiyan H, Ehrhart M, Alaoui AE, Fassi LE, Eugenio P, Fegan S, Fersch R, Filippi A, Forest TA, Ghandilyan Y, Gavalian G, Gilfoyle GP, Giovanetti KL, Girod FX, Glazier DI, Golovatch E, Gothe RW, Griffioen KA, Guidal M, Guo L, Hafidi K, Hakobyan H, Hattawy M, Hayward TB, Heddle D, Hicks K, Hobart A, Holtrop M, Huang Q, Ilieva Y, Ireland DG, Ishkhanov BS, Isupov EL, Jenkins D, Jo HS, Joo K, Keller D, Khanal A, Khandaker M, Kim CW, Kim W, Klein FJ, Kubarovsky V, Kuhn SE, Lanza L, Leali M, Lenisa P, Livingston K, MacGregor IJD, Marchand D, Markov N, Marsicano L, Mascagna V, McKinnon B, Milner RG, Mineeva T, Mokeev V, Mullen C, Camacho CM, Neupane K, Niculescu G, O'Connell T, Osipenko M, Paolone M, Pappalardo LL, Paremuzyan R, Park K, Pasyuk E, Phelps W, Pocanic D, Pogorelko O, Poudel J, Prok Y, Raue BA, Ripani M, Ritman J, Rizzo A, Rossi P, Sabatié F, Salgado C, Schmidt A, Schumacher RA, Sharabian YG, Shrestha U, Soto O, Sparveris N, Stepanyan S, Strakovsky II, Strauch S, Tyler N, Ungaro M, Venturelli L, Voskanyan H, Vossen A, Voutier E, Watts D, Wei K, Wei X, Wood MH, Yale B, Zachariou N, Zhang J, and Zhao ZW
Abstract: A first measurement of the longitudinal beam spin asymmetry A_{LU} in the semi-inclusive electroproduction of pairs of charged pions is reported. A_{LU} is a higher-twist observable and offers the cleanest access to the nucleon twist-3 parton distribution function e(x). Data have been collected in the Hall-B at Jefferson Lab by impinging a 5.498-GeV electron beam on a liquid-hydrogen target, and reconstructing the scattered electron and the pion pair with the CLAS detector. One-dimensional projections of the A_{LU}^{sinϕ_{R}} moments are extracted for the kinematic variables of interest in the valence quark region. The understanding of dihadron production is essential for the interpretation of observables in single-hadron production in semi-inclusive DIS, and pioneering measurements of single-spin asymmetries in dihadron production open a new avenue in studies of QCD dynamics.
Published: 2021
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26. Extraction of Beam-Spin Asymmetries from the Hard Exclusive π^{+} Channel off Protons in a Wide Range of Kinematics.

Author: Diehl S, Joo K, Kim A, Avakian H, Kroll P, Park K, Riser D, Semenov-Tian-Shansky K, Tezgin K, Adhikari KP, Adhikari S, Amaryan MJ, Angelini G, Asryan G, Atac H, Barion L, Battaglieri M, Bedlinskiy I, Benmokhtar F, Bianconi A, Biselli AS, Bossù F, Boiarinov S, Briscoe WJ, Brooks WK, Bulumulla D, Burkert VD, Carman DS, Carvajal JC, Celentano A, Chatagnon P, Chetry T, Ciullo G, Clark L, Cole PL, Contalbrigo M, Crede V, D'Angelo A, Dashyan N, De Vita R, Defurne M, Deur A, Dilks C, Djalali C, Dupre R, Egiyan H, Ehrhart M, El Alaoui A, El Fassi L, Eugenio P, Filippi A, Forest TA, Ghandilyan Y, Gilfoyle GP, Giovanetti KL, Girod FX, Glazier DI, Golovatch E, Gothe RW, Griffioen KA, Guidal M, Guo L, Hakobyan H, Harrison N, Hattawy M, Hayward TB, Heddle D, Hicks K, Holtrop M, Ilieva Y, Ireland DG, Ishkhanov BS, Isupov EL, Jenkins D, Jo HS, Joosten S, Keller D, Khachatryan M, Khanal A, Khandaker M, Kim CW, Kim W, Kubarovsky V, Kuhn SE, Lanza L, Leali M, Lenisa P, Livingston K, MacGregor IJD, Marchand D, Markov N, Marsicano L, Mascagna V, McKinnon B, Meziani ZE, Mineeva T, Mirazita M, Mokeev V, Munoz Camacho C, Nadel-Turonski P, Niculescu G, Osipenko M, Paolone M, Pappalardo LL, Pasyuk E, Phelps W, Pogorelko O, Price JW, Prok Y, Raue BA, Ripani M, Rizzo A, Rossi P, Rowley J, Sabatié F, Salgado C, Schmidt A, Schumacher RA, Sharabian YG, Shrestha U, Soto O, Sparveris N, Stepanyan S, Stoler P, Strakovsky II, Strauch S, Tan JA, Tyler N, Ungaro M, Venturelli L, Voskanyan H, Voutier E, Watts DP, Wei X, Wood MH, Zachariou N, Zhang J, and Zhao ZW
Abstract: We have measured beam-spin asymmetries to extract the sinϕ moment A_{LU}^{sinϕ} from the hard exclusive e[over →]p→e^{'}nπ^{+} reaction above the resonance region, for the first time with nearly full coverage from forward to backward angles in the center of mass. The A_{LU}^{sinϕ} moment has been measured up to 6.6 GeV^{2} in -t, covering the kinematic regimes of generalized parton distributions (GPD) and baryon-to-meson transition distribution amplitudes (TDA) at the same time. The experimental results in very forward kinematics demonstrate the sensitivity to chiral-odd and chiral-even GPDs. In very backward kinematics where the TDA framework is applicable, we found A_{LU}^{sinϕ} to be negative, while a sign change was observed near 90° in the center of mass. The unique results presented in this Letter will provide critical constraints to establish reaction mechanisms that can help to further develop the GPD and TDA frameworks.
Published: 2020
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27. Exploring the Structure of the Bound Proton with Deeply Virtual Compton Scattering.

Author: Hattawy M, Baltzell NA, Dupré R, Bültmann S, De Vita R, El Alaoui A, El Fassi L, Egiyan H, Girod FX, Guidal M, Hafidi K, Jenkins D, Liuti S, Perrin Y, Stepanyan S, Torayev B, Voutier E, Adhikari S, Angelini G, Ayerbe Gayoso C, Barion L, Battaglieri M, Bedlinskiy I, Biselli AS, Bossù F, Brooks W, Cao F, Carman DS, Celentano A, Chatagnon P, Chetry T, Ciullo G, Clark L, Cole PL, Contalbrigo M, Crede V, D'Angelo A, Dashyan N, De Sanctis E, Defurne M, Deur A, Diehl S, Djalali C, Ehrhart M, Eugenio P, Fegan S, Filippi A, Forest TA, Fradi A, Garçon M, Gavalian G, Gevorgyan N, Gilfoyle GP, Giovanetti KL, Golovatch E, Gothe RW, Griffioen KA, Harrison N, Hauenstein F, Hayward TB, Heddle D, Hicks K, Holtrop M, Ilieva Y, Ireland DG, Isupov EL, Jo HS, Johnston S, Keller D, Khachatryan G, Khachatryan M, Khanal A, Khandaker M, Kim CW, Kim W, Klein FJ, Kubarovsky V, Kuhn SE, Lanza L, L Kabir M, Lenisa P, Livingston K, MacGregor IJD, Marchand D, Markov N, Mayer M, McKinnon B, Meziani ZE, Mineeva T, Mirazita M, Montgomery RA, Munoz Camacho C, Nadel-Turonski P, Niccolai S, Ostrovidov AI, Pappalardo LL, Paremuzyan R, Pasyuk E, Pogorelko O, Poudel J, Prok Y, Protopopescu D, Ripani M, Riser D, Rizzo A, Rosner G, Rossi P, Sabatié F, Salgado C, Schumacher RA, Sharabian YG, Skorodumina I, Sokhan D, Soto O, Sparveris N, Strauch S, Taiuti M, Tan JA, Tyler N, Ungaro M, Voskanyan H, Wang R, Watts DP, Wei X, Weinstein LB, Wood MH, Zachariou N, Zhang J, and Zhao ZW
Abstract: In the past two decades, deeply virtual Compton scattering of electrons has been successfully used to advance our knowledge of the partonic structure of the free proton and investigate correlations between the transverse position and the longitudinal momentum of quarks inside the nucleon. Meanwhile, the structure of bound nucleons in nuclei has been studied in inclusive deep-inelastic lepton scattering experiments off nuclear targets, showing a significant difference in longitudinal momentum distribution of quarks inside the bound nucleon, known as the EMC effect. In this Letter, we report the first beam spin asymmetry (BSA) measurement of exclusive deeply virtual Compton scattering off a proton bound in ^{4}He. The data used here were accumulated using a 6 GeV longitudinally polarized electron beam incident on a pressurized ^{4}He gaseous target placed within the CLAS spectrometer in Hall-B at the Thomas Jefferson National Accelerator Facility. The azimuthal angle (ϕ) dependence of the BSA was studied in a wide range of virtual photon and scattered proton kinematics. The Q^{2}, x_{B}, and t dependencies of the BSA on the bound proton are compared with those on the free proton. In the whole kinematical region of our measurements, the BSA on the bound proton is smaller by 20% to 40%, indicating possible medium modification of its partonic structure.
Published: 2019
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28. Direct Observation of Proton-Neutron Short-Range Correlation Dominance in Heavy Nuclei.

Author: Duer M, Schmidt A, Pybus JR, Segarra EP, Hrnjic A, Denniston AW, Weiss R, Hen O, Piasetzky E, Weinstein LB, Barnea N, Korover I, Cohen EO, Hakobyan H, Adhikari S, Angelini G, Battaglieri M, Beck A, Bedlinskiy I, Biselli AS, Boiarinov S, Brooks W, Burkert VD, Cao F, Carman DS, Celentano A, Chetry T, Ciullo G, Clark L, Cole PL, Contalbrigo M, Cortes O, Crede V, Cruz Torres R, D'Angelo A, Dashyan N, De Sanctis E, De Vita R, Deur A, Diehl S, Djalali C, Dupre R, Duran B, Egiyan H, El Alaoui A, El Fassi L, Eugenio P, Filippi A, Forest TA, Gilfoyle GP, Giovanetti KL, Girod FX, Golovatch E, Gothe RW, Griffioen KA, Guo L, Hafidi K, Hanretty C, Harrison N, Hattawy M, Hauenstein F, Hayward TB, Heddle D, Hicks K, Holtrop M, Ilieva Y, Ireland DG, Ishkhanov BS, Isupov EL, Jo HS, Joo K, Kabir ML, Keller D, Khachatryan M, Khanal A, Khandaker M, Kim W, Klein FJ, Kubarovsky V, Kuhn SE, Lanza L, Laskaris G, Lenisa P, Livingston K, MacGregor IJD, Marchand D, Markov N, McKinnon B, Mey-Tal Beck S, Mirazita M, Mokeev V, Montgomery RA, Movsisyan A, Munoz Camacho C, Mustapha B, Nadel-Turonski P, Niccolai S, Niculescu G, Osipenko M, Ostrovidov AI, Paolone M, Paremuzyan R, Park K, Pasyuk E, Patsyuk M, Phelps W, Pogorelko O, Prok Y, Protopopescu D, Ripani M, Rizzo A, Rosner G, Rossi P, Sabatié F, Schmookler BA, Schumacher RA, Sharabian Y, Skorodumina I, Sokhan D, Sparveris N, Stepanyan S, Strauch S, Taiuti M, Tan JA, Tyler N, Ungaro M, Voskanyan H, Voutier E, Wang R, Wei X, Wood MH, Zachariou N, Zhang J, Zhao ZW, and Zheng X
Abstract: We measured the triple coincidence A(e,e^{'}np) and A(e,e^{'}pp) reactions on carbon, aluminum, iron, and lead targets at Q^{2}>1.5 (GeV/c)^{2}, x_{B}>1.1 and missing momentum >400 MeV/c. This was the first direct measurement of both proton-proton (pp) and neutron-proton (np) short-range correlated (SRC) pair knockout from heavy asymmetric nuclei. For all measured nuclei, the average proton-proton (pp) to neutron-proton (np) reduced cross-section ratio is about 6%, in agreement with previous indirect measurements. Correcting for single-charge exchange effects decreased the SRC pairs ratio to ∼3%, which is lower than previous results. Comparisons to theoretical generalized contact formalism (GCF) cross-section calculations show good agreement using both phenomenological and chiral nucleon-nucleon potentials, favoring a lower pp to np pair ratio. The ability of the GCF calculation to describe the experimental data using either phenomenological or chiral potentials suggests possible reduction of scale and scheme dependence in cross-section ratios. Our results also support the high-resolution description of high-momentum states being predominantly due to nucleons in SRC pairs.
Published: 2019
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29. Center of Mass Motion of Short-Range Correlated Nucleon Pairs studied via the A(e,e^{'}pp) Reaction.

Author: Cohen EO, Hen O, Piasetzky E, Weinstein LB, Duer M, Schmidt A, Korover I, Hakobyan H, Adhikari S, Akbar Z, Amaryan MJ, Avakian H, Ball J, Barion L, Battaglieri M, Beck A, Bedlinskiy I, Biselli AS, Boiarinov S, Briscoe W, Burkert VD, Cao F, Carman DS, Celentano A, Charles G, Chatagnon P, Chetry T, Ciullo G, Clary BA, Contalbrigo M, Crede V, Cruz Torres R, D'Angelo A, Dashyan N, De Vita R, De Sanctis E, Defurne M, Deur A, Diehl S, Djalali C, Duer M, Dupre R, Egiyan H, Ehrhart M, El Alaoui A, Fassi LE, Eugenio P, Fedotov G, Fersch R, Filippi A, Ghandilyan Y, Giovanetti KL, Girod FX, Golovatch E, Gothe RW, Griffioen KA, Hafidi K, Harrison N, Hauenstein F, Heddle D, Hicks K, Holtrop M, Ireland DG, Ishkhanov BS, Isupov EL, Jenkins D, Jo HS, Johnston S, Kabir ML, Keller D, Khachatryan G, Khachatryan M, Khandaker M, Kim A, Kim W, Klein A, Klein FJ, Korover I, Kubarovsky V, Kuhn SE, Lanza L, Lenisa P, Livingston K, MacGregor IJD, Marchand D, McKinnon B, Mey-Tal Beck S, Meyer CA, Mirazita M, Mokeev V, Montgomery RA, Movsisyan A, Munoz Camacho C, Mustapha B, Nadel-Turonski P, Niccolai S, Niculescu G, Osipenko M, Ostrovidov AI, Paolone M, Paremuzyan R, Pasyuk E, Pogorelko O, Price JW, Prok Y, Protopopescu D, Ripani M, Riser D, Rizzo A, Rosner G, Rossi P, Sabatié F, Schmookler BA, Schumacher RA, Sharabian YG, Sokhan D, Sparveris N, Stepanyan S, Strauch S, Taiuti M, Tan JA, Ungaro M, Voskanyan H, Voutier E, Wang R, Watts DP, Wei X, Wood MH, Zachariou N, Zhang J, Zheng X, and Zhao ZW
Abstract: Short-range correlated (SRC) nucleon pairs are a vital part of the nucleus, accounting for almost all nucleons with momentum greater than the Fermi momentum (k_{F}). A fundamental characteristic of SRC pairs is having large relative momenta as compared to k_{F}, and smaller center of mass (c.m.) which indicates a small separation distance between the nucleons in the pair. Determining the c.m. momentum distribution of SRC pairs is essential for understanding their formation process. We report here on the extraction of the c.m. motion of proton-proton (pp) SRC pairs in carbon and, for the first time in heavier and ansymetric nuclei: aluminum, iron, and lead, from measurements of the A(e,e^{'}pp) reaction. We find that the pair c.m. motion for these nuclei can be described by a three-dimensional Gaussian with a narrow width ranging from 140 to 170 MeV/c, approximately consistent with the sum of two mean-field nucleon momenta. Comparison with calculations appears to show that the SRC pairs are formed from mean-field nucleons in specific quantum states.
Published: 2018
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30. Measurement of the Q^{2} Dependence of the Deuteron Spin Structure Function g_{1} and its Moments at Low Q^{2} with CLAS.

Author: Adhikari KP, Deur A, El Fassi L, Kang H, Kuhn SE, Ripani M, Slifer K, Zheng X, Adhikari S, Akbar Z, Amaryan MJ, Avakian H, Ball J, Balossino I, Barion L, Battaglieri M, Bedlinskiy I, Biselli AS, Bosted P, Briscoe WJ, Brock J, Bültmann S, Burkert VD, Thanh Cao F, Carlin C, Carman DS, Celentano A, Charles G, Chen JP, Chetry T, Choi S, Ciullo G, Clark L, Cole PL, Contalbrigo M, Crede V, D'Angelo A, Dashyan N, De Vita R, De Sanctis E, Defurne M, Djalali C, Dodge GE, Drozdov V, Dupre R, Egiyan H, El Alaoui A, Elouadrhiri L, Eugenio P, Fedotov G, Filippi A, Ghandilyan Y, Gilfoyle GP, Golovatch E, Gothe RW, Griffioen KA, Guidal M, Guler N, Guo L, Hafidi K, Hakobyan H, Hanretty C, Harrison N, Hattawy M, Heddle D, Hicks K, Holtrop M, Hyde CE, Ilieva Y, Ireland DG, Isupov EL, Jenkins D, Jo HS, Johnston SC, Joo K, Joosten S, Kabir ML, Keith CD, Keller D, Khachatryan G, Khachatryan M, Khandaker M, Kim W, Klein A, Klein FJ, Konczykowski P, Kovacs K, Kubarovsky V, Lanza L, Lenisa P, Livingston K, Long E, MacGregor IJD, Markov N, Mayer M, McKinnon B, Meekins DG, Meyer CA, Mineeva T, Mirazita M, Mokeev V, Movsisyan A, Munoz Camacho C, Nadel-Turonski P, Niculescu G, Niccolai S, Osipenko M, Ostrovidov AI, Paolone M, Pappalardo L, Paremuzyan R, Park K, Pasyuk E, Payette D, Phelps W, Phillips SK, Pierce J, Pogorelko O, Poudel J, Price JW, Prok Y, Protopopescu D, Raue BA, Rizzo A, Rosner G, Rossi P, Sabatié F, Salgado C, Schumacher RA, Sharabian YG, Shigeyuki T, Simonyan A, Skorodumina I, Smith GD, Sparveris N, Sokhan D, Stepanyan S, Strakovsky II, Strauch S, Sulkosky V, Taiuti M, Tan JA, Ungaro M, Voutier E, Wei X, Weinstein LB, Zhang J, and Zhao ZW
Abstract: We measured the g_{1} spin structure function of the deuteron at low Q^{2}, where QCD can be approximated with chiral perturbation theory (χPT). The data cover the resonance region, up to an invariant mass of W≈1.9 GeV. The generalized Gerasimov-Drell-Hearn sum, the moment Γ_{1}^{d} and the spin polarizability γ_{0}^{d} are precisely determined down to a minimum Q^{2} of 0.02 GeV^{2} for the first time, about 2.5 times lower than that of previous data. We compare them to several χPT calculations and models. These results are the first in a program of benchmark measurements of polarization observables in the χPT domain.
Published: 2018
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31. First Exclusive Measurement of Deeply Virtual Compton Scattering off ^{4}He: Toward the 3D Tomography of Nuclei.

Author: Hattawy M, Baltzell NA, Dupré R, Hafidi K, Stepanyan S, Bültmann S, De Vita R, El Alaoui A, El Fassi L, Egiyan H, Girod FX, Guidal M, Jenkins D, Liuti S, Perrin Y, Torayev B, Voutier E, Adhikari KP, Adhikari S, Adikaram D, Akbar Z, Amaryan MJ, Anefalos Pereira S, Armstrong WR, Avakian H, Ball J, Bashkanov M, Battaglieri M, Batourine V, Bedlinskiy I, Biselli AS, Boiarinov S, Briscoe WJ, Brooks WK, Burkert VD, Thanh Cao F, Carman DS, Celentano A, Charles G, Chetry T, Ciullo G, Clark L, Colaneri L, Cole PL, 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 JA, Forest TA, Fradi A, Garçon M, Gevorgyan N, Ghandilyan Y, Gilfoyle GP, Giovanetti KL, Gleason C, Gohn W, Golovatch E, Gothe RW, Griffioen KA, Guo L, Hakobyan H, Hanretty C, Harrison N, Heddle D, Hicks K, Holtrop M, Hughes SM, Ireland DG, Ishkhanov BS, Isupov EL, Jiang H, Joo K, Joosten S, Keller D, Khachatryan G, Khachatryan M, Khandaker M, Kim A, Kim W, Klein A, Klein FJ, Kubarovsky V, Kuhn SE, Kuleshov SV, Lanza L, Lenisa P, Livingston K, Lu HY, MacGregor IJD, Markov N, Mayer M, McCracken ME, McKinnon B, Meyer CA, Meziani ZE, Mineeva T, Mirazita M, Mokeev V, Montgomery RA, Moutarde H, Movsisyan A, Munoz Camacho C, Nadel-Turonski P, Net LA, Niccolai S, Niculescu G, Niculescu I, Osipenko M, Ostrovidov AI, Paolone M, Paremuzyan R, Park K, Pasyuk E, Phelps E, Phelps W, Pisano S, Pogorelko O, Price JW, Prok Y, Protopopescu D, Ripani M, Ritchie BG, Rizzo A, Rosner G, Rossi P, Sabatié F, Salgado C, Schumacher RA, Seder E, Sharabian YG, Simonyan A, Skorodumina I, Smith GD, Sokhan D, Sparveris N, Strauch S, Taiuti M, Ungaro M, Voskanyan H, Walford NK, Watts DP, Wei X, Weinstein LB, Wood MH, Zachariou N, Zana L, Zhang J, and Zhao ZW
Abstract: We report on the first measurement of the beam-spin asymmetry in the exclusive process of coherent deeply virtual Compton scattering off a nucleus. The experiment uses the 6 GeV electron beam from the Continuous Electron Beam Accelerator Facility (CEBAF) accelerator at Jefferson Lab incident on a pressurized ^{4}He gaseous target placed in front of the CEBAF Large Acceptance Spectrometer (CLAS). The scattered electron is detected by CLAS and the photon by a dedicated electromagnetic calorimeter at forward angles. To ensure the exclusivity of the process, a specially designed radial time projection chamber is used to detect the recoiling ^{4}He nuclei. We measure beam-spin asymmetries larger than those observed on the free proton in the same kinematic domain. From these, we are able to extract, in a model-independent way, the real and imaginary parts of the only ^{4}He Compton form factor, 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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32. 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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33. 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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34. 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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35. 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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36. Measurement of the neutron F2 structure function via spectator tagging with CLAS.

Author: Baillie N, Tkachenko S, Zhang J, Bosted P, Bültmann S, Christy ME, Fenker H, Griffioen KA, Keppel CE, Kuhn SE, Melnitchouk W, Tvaskis V, Adhikari KP, Adikaram D, Aghasyan M, Amaryan MJ, Anghinolfi M, Arrington J, Avakian H, Baghdasaryan H, Battaglieri M, Biselli AS, Branford D, Briscoe WJ, Brooks WK, Burkert VD, Carman DS, Celentano A, Chandavar S, Charles G, Cole PL, 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, El Alaoui A, El Fassi L, Elouadrhiri L, Eugenio P, Fedotov G, Fegan S, Fradi A, Gabrielyan MY, Gevorgyan N, Gilfoyle GP, Giovanetti KL, Girod FX, Gohn W, Golovatch E, Gothe RW, Graham L, Guegan B, Guidal M, Guler N, Guo L, Hafidi K, Heddle D, Hicks K, Holtrop M, Hungerford E, Hyde CE, Ilieva Y, Ireland DG, Ispiryan M, Isupov EL, Jawalkar SS, Jo HS, Kalantarians N, Khandaker M, Khetarpal P, Kim A, Kim W, King PM, Klein A, Klein FJ, Klimenko A, Kubarovsky V, Kuleshov SV, Kvaltine ND, Livingston K, Lu HY, MacGregor IJ, 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 AI, Pappalardo L, Park K, Park S, Pasyuk E, Anefalos Pereira S, Pisano S, Pozdniakov S, Price JW, Procureur S, Prok Y, Protopopescu D, Raue BA, Ricco G, Rimal D, Ripani M, Rosner G, Rossi P, Sabatié F, Saini MS, Salgado C, Schott D, Schumacher RA, Seder E, Sharabian YG, Sober DI, Sokhan D, Stepanyan S, Stepanyan SS, Stoler P, Strauch S, Taiuti M, Tang W, Ungaro M, Vineyard MF, Voutier E, Watts DP, Weinstein LB, Weygand DP, Wood MH, Zana L, and Zhao B
Abstract: We report on the first measurement of the F(2) structure function of the neutron from the 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/c and their angles to ≳100° relative to the momentum transfer allows an interpretation of the process in terms of scattering from nearly on-shell neutrons. The F(2)(n) data collected cover the nucleon-resonance and deep-inelastic regions over a wide range of Bjorken x for 0.65
Published: 2012
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37. Measurement of single- and double-spin asymmetries in deep inelastic pion electroproduction with a longitudinally polarized target.

Author: Avakian H, Bosted P, Burkert VD, Elouadrhiri L, Adhikari KP, Aghasyan M, Amaryan M, Anghinolfi M, Baghdasaryan H, Ball J, Battaglieri M, Bedlinskiy I, Biselli AS, Branford D, Briscoe WJ, Brooks W, Carman DS, Casey L, Cole PL, Collins P, Crabb D, Crede V, D'Angelo A, Daniel A, Dashyan N, De Vita R, De Sanctis E, Deur A, Dey B, Dhamija S, Dickson R, Djalali C, Dodge G, Doughty D, Dupre R, El Alaoui A, Eugenio P, Fegan S, Fersch R, Forest TA, Fradi A, Gabrielyan MY, Gavalian G, Gevorgyan N, Gilfoyle GP, Giovanetti KL, Girod FX, Gohn W, Gothe RW, Griffioen KA, Guidal M, Guler N, Guo L, Hafidi K, Hakobyan H, Hanretty C, Hassall N, Heddle D, Hicks K, Holtrop M, Ilieva Y, Ireland DG, Isupov EL, Jawalkar SS, Jo HS, Joo K, Keller D, Khandaker M, Khetarpal P, Kim W, Klein A, Klein FJ, Konczykowski P, Kubarovsky V, Kuhn SE, Kuleshov SV, Kuznetsov V, Livingston K, Lu HY, Markov N, Mayer M, Martinez D, McAndrew J, McCracken ME, McKinnon B, Meyer CA, Mineeva T, Mirazita M, Mokeev V, Moreno B, Moriya K, Morrison B, Moutarde H, Munevar E, Nadel-Turonski P, Nasseripour R, Niccolai S, Niculescu G, Niculescu I, Niroula MR, Osipenko M, Ostrovidov AI, Paremuzyan R, Park K, Park S, Pasyuk E, Pereira SA, Perrin Y, Pisano S, Pogorelko O, Price JW, Procureur S, Prok Y, Protopopescu D, Raue BA, Ricco G, Ripani M, Rosner G, Rossi P, Sabatié F, Saini MS, Salamanca J, Salgado C, Schumacher RA, Seder E, Seraydaryan H, Sharabian YG, Sober DI, Sokhan D, Stepanyan SS, Stepanyan S, Stoler P, Strauch S, Suleiman R, Taiuti M, Tedeschi DJ, Tkachenko S, Ungaro M, Vernarsky B, Vineyard MF, Voutier E, Watts DP, Weinstein LB, Weygand DP, Wood MH, Zhang J, Zhao B, and Zhao ZW
Abstract: We report the first measurement of the transverse momentum dependence of double-spin asymmetries in semi-inclusive production of pions in deep-inelastic scattering off the longitudinally polarized proton. Data have been obtained using a polarized electron beam of 5.7 GeV with the CLAS detector at the Jefferson Lab (JLab). Modulations of single spin asymmetries over the azimuthal angle between lepton scattering and hadron production planes ϕ have been measured over a wide kinematic range in Bjorken x and virtual photon squared four-momentum Q2. A significant nonzero sin2ϕ single spin asymmetry was observed for the first time indicating strong spin-orbit correlations for transversely polarized quarks in the longitudinally polarized proton.
Published: 2010
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38. Tensor correlations measured in 3He(e,e' pp)n.

Author: Baghdasaryan H, Weinstein LB, Laget JM, Adhikari KP, Aghasyan M, Amarian M, Anghinolfi M, Avakian H, Ball J, Battaglieri M, Bedlinskiy I, Bennett RP, Berman BL, Biselli AS, Bookwalter C, Briscoe WJ, Brooks WK, Bültmann S, Burkert VD, Carman DS, Crede V, D'Angelo A, Daniel A, Dashyan N, De Vita R, De Sanctis E, Deur A, Dey B, Dickson R, Djalali C, Dodge GE, Doughty D, Dupre R, Egiyan H, El Alaoui A, El Fassi L, Eugenio P, Fegan S, Gabrielyan MY, Gilfoyle GP, Giovanetti KL, Gohn W, Gothe RW, Griffioen KA, Guidal M, Guo L, Gyurjyan V, Hakobyan H, Hanretty C, Hyde CE, Hicks K, Holtrop M, Ilieva Y, Ireland DG, Joo K, Keller D, Khandaker M, Khetarpal P, Kim A, Kim W, Klein A, Klein FJ, Konczykowski P, Kubarovsky V, Kuhn SE, Kuleshov SV, Kuznetsov V, Kvaltine ND, Livingston K, Lu HY, Macgregor IJ, Markov N, Mayer M, McAndrew J, McKinnon B, Meyer CA, Mikhailov K, Mokeev V, Moreno B, Moriya K, Morrison B, Moutarde H, Munevar E, Nadel-Turonski P, Nepali C, Niccolai S, Niculescu G, Niculescu I, Osipenko M, Ostrovidov AI, Paremuzyan R, Park K, Park S, Pasyuk E, Pereira SA, Pisano S, Pogorelko O, Pozdniakov S, Price JW, Procureur S, Protopopescu D, Ricco G, Ripani M, Rosner G, Rossi P, Sabatié F, Salgado C, Schumacher RA, Seraydaryan H, Smith GD, Sober DI, Sokhan D, Stepanyan SS, Stepanyan S, Stoler P, Strauch S, Taiuti M, Tang W, Taylor CE, Tedeschi DJ, Ungaro M, Vineyard MF, Voutier E, Watts DP, Weygand DP, Wood MH, Zhao B, and Zhao ZW
Abstract: We have measured the 3He(e,e' pp)n reaction at an incident energy of 4.7 GeV over a wide kinematic range. We identified spectator correlated pp and pn nucleon pairs by using kinematic cuts and measured their relative and total momentum distributions. This is the first measurement of the ratio of pp to pn pairs as a function of pair total momentum p(tot). For pair relative momenta between 0.3 and 0.5 GeV/c, the ratio is very small at low p(tot) and rises to approximately 0.5 at large p(tot). This shows the dominance of tensor over central correlations at this relative momentum.
Published: 2010
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39. Measurement of the differential cross section for the reaction gamman-->pi- p from deuterium.

Author: Chen W, Mibe T, Dutta D, Gao H, Laget JM, Mirazita M, Rossi P, Stepanyan S, Strakovsky II, Amaryan MJ, Anghinolfi M, Bagdasaryan H, Battaglieri M, Bellis M, Berman BL, Biselli AS, Bookwalter C, Branford D, Briscoe WJ, Brooks WK, Burkert VD, Careccia SL, Carman DS, Casey L, Cole PL, Collins P, Crede V, Daniel A, Dashyan N, De Vita R, De Sanctis E, Deur A, Dhamija S, Dickson R, Djalali C, Dodge GE, Doughty D, Egiyan H, Eugenio P, Fedotov G, Fradi A, Garçon M, Gilfoyle GP, Giovanetti KL, Girod FX, Gohn W, Gothe RW, Griffioen KA, Guidal M, Hakobyan H, Hanretty C, Hassall N, Heddle D, Hicks K, Holtrop M, Hyde CE, Ilieva Y, Ireland DG, Ishkhanov BS, Isupov EL, Jo HS, Johnstone JR, Joo K, Keller D, Khandaker M, Khetarpal P, Kim W, Klein A, Klein FJ, Kramer LH, Kubarovsky V, Kuhn SE, Kuleshov SV, Kuznetsov V, Livingston K, Lu HY, Markov N, McCracken ME, McKinnon B, Meyer CA, Mineeva T, Mokeev V, Moreno B, Moriya K, Nadel-Turonski P, Nasseripour R, Niccolai S, Niculescu I, Niroula MR, Osipenko M, Ostrovidov AI, Park K, Park S, Pereira SA, Pogorelko O, Pozdniakov S, Price JW, Procureur S, Protopopescu D, Raue BA, Ricco G, Ripani M, Ritchie BG, Rosner G, Sabatié F, Saini MS, Salamanca J, Salgado C, Schumacher RA, Sharabian YG, Sober DI, Sokhan D, Stepanyan SS, Strauch S, Taiuti M, Tedeschi DJ, Tkachenko S, Ungaro M, Vineyard MF, Watts DP, Weinstein LB, Weygand DP, Wood MH, Yegneswaran A, Zhang J, and Zhao B
Abstract: We report a measurement of the differential cross section for the gamman-->pi- p process from the CLAS detector at Jefferson Laboratory in Hall B for photon energies between 1.0 and 3.5 GeV and pion center-of-mass (c.m.) angles (thetac.m.) between 50 degrees and 115 degrees. We confirm a previous indication of a broad enhancement around a c.m. energy ([sqrt]s) of 2.1 GeV at thetac.m.=90 degrees in the scaled differential cross section s7dsigma/dt and a rapid falloff in a center-of-mass energy region of about 400 MeV following the enhancement. Our data show an angular dependence of this enhancement as the suggested scaling region is approached for thetac.m. from 70 degrees to 105 degrees.
Published: 2009
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40. Precise measurement of the neutron magnetic form factor G(M)n in the few-GeV2 region.

Author: Lachniet J, Afanasev A, Arenhövel H, Brooks WK, Gilfoyle GP, Higinbotham D, Jeschonnek S, Quinn B, Vineyard MF, Adams G, Adhikari KP, Amaryan MJ, Anghinolfi M, Asavapibhop B, Asryan G, Avakian H, Bagdasaryan H, Baillie N, Ball JP, Baltzell NA, Barrow S, Batourine V, Battaglieri M, Beard K, Bedlinskiy I, Bektasoglu M, Bellis M, Benmouna N, Berman BL, Biselli AS, Bonner BE, Bookwalter C, Bouchigny S, Boiarinov S, Bradford R, Branford D, Briscoe WJ, Bültmann S, Burkert VD, Calarco JR, Careccia SL, Carman DS, Casey L, Cheng L, Cole PL, Coleman A, Collins P, Cords D, Corvisiero P, Crabb D, Crede V, Cummings JP, Dale D, Daniel A, Dashyan N, De Masi R, De Vita R, De Sanctis E, Degtyarenko PV, Denizli H, Dennis L, Deur A, Dhamija S, Dharmawardane KV, Dhuga KS, Dickson R, Djalali C, Dodge GE, Doughty D, Dragovitsch P, Dugger M, Dytman S, Dzyubak OP, Egiyan H, Egiyan KS, El Fassi L, Elouadrhiri L, Empl A, Eugenio P, Fatemi R, Fedotov G, Fersch R, Feuerbach RJ, Forest TA, Fradi A, Gabrielyan MY, Garçon M, Gavalian G, Gevorgyan N, Giovanetti KL, Girod FX, Goetz JT, Gohn W, Golovatch E, Gothe RW, Graham L, Griffioen KA, Guidal M, Guillo M, Guler N, Guo L, Gyurjyan V, Hadjidakis C, Hafidi K, Hakobyan H, Hanretty C, Hardie J, Hassall N, Heddle D, Hersman FW, Hicks K, Hleiqawi I, Holtrop M, Hu J, Huertas M, Hyde-Wright CE, Ilieva Y, Ireland DG, Ishkhanov BS, Isupov EL, Ito MM, Jenkins D, Jo HS, Johnstone JR, Joo K, Juengst HG, Kageya T, Kalantarians N, Keller D, Kellie JD, Khandaker M, Khetarpal P, Kim KY, Kim K, Kim W, Klein A, Klein FJ, Klusman M, Konczykowski P, Kossov M, Kramer LH, Kubarovsky V, Kuhn J, Kuhn SE, Kuleshov SV, Kuznetsov V, Laget JM, Langheinrich J, Lawrence D, Lima AC, Livingston K, Lowry M, Lu HY, Lukashin K, Maccormick M, Malace S, Manak JJ, Markov N, Mattione P, McAleer S, McCracken ME, McKinnon B, McNabb JW, Mecking BA, Mestayer MD, Meyer CA, Mibe T, Mikhailov K, Mineeva T, Minehart R, Mirazita M, Miskimen R, Mokeev V, Moreno B, Moriya K, Morrow SA, Moteabbed M, Mueller J, Munevar E, Mutchler GS, Nadel-Turonski P, Nasseripour R, Niccolai S, Niculescu G, Niculescu I, Niczyporuk BB, Niroula MR, Niyazov RA, Nozar M, O'Rielly GV, Osipenko M, Ostrovidov AI, Park K, Park S, Pasyuk E, Paterson C, Pereira SA, Philips SA, Pierce J, Pivnyuk N, Pocanic D, Pogorelko O, Polli E, Popa I, Pozdniakov S, Preedom BM, Price JW, Prok Y, Protopopescu D, Qin LM, Raue BA, Riccardi G, Ricco G, Ripani M, Ritchie BG, Rosner G, Rossi P, Rowntree D, Rubin PD, Sabatié F, Saini MS, Salamanca J, Salgado C, Sandorfi A, Santoro JP, Sapunenko V, Schott D, Schumacher RA, Serov VS, Sharabian YG, Sharov D, Shaw J, Shvedunov NV, Skabelin AV, Smith ES, Smith LC, Sober DI, Sokhan D, Starostin A, Stavinsky A, Stepanyan S, Stepanyan SS, Stokes BE, Stoler P, Stopani KA, Strakovsky II, Strauch S, Suleiman R, Taiuti M, Taylor S, Tedeschi DJ, Thompson R, Tkabladze A, Tkachenko S, Ungaro M, Vlassov AV, Watts DP, Wei X, Weinstein LB, Weygand DP, Williams M, Wolin E, Wood MH, Yegneswaran A, Yun J, Yurov M, Zana L, Zhang J, Zhao B, and Zhao ZW
Abstract: The neutron elastic magnetic form factor was extracted from quasielastic electron scattering on deuterium over the range Q;{2}=1.0-4.8 GeV2 with the CLAS detector at Jefferson Lab. High precision was achieved with a ratio technique and a simultaneous in situ calibration of the neutron detection efficiency. Neutrons were detected with electromagnetic calorimeters and time-of-flight scintillators at two beam energies. The dipole parametrization gives a good description of the data.
Published: 2009
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41. Measurement of direct f0(980) photoproduction on the proton.

Author: Battaglieri M, De Vita R, Szczepaniak AP, Adhikari KP, Aghasyan M, Amaryan MJ, Ambrozewicz P, Anghinolfi M, Asryan G, Avakian H, Bagdasaryan H, Baillie N, Ball JP, Baltzell NA, Batourine V, Bedlinskiy I, Bellis M, Benmouna N, Berman BL, Bibrzycki L, Biselli AS, Bookwalter C, Bouchigny S, Boiarinov S, Bradford R, Branford D, Briscoe WJ, Brooks WK, Bültmann S, Burkert VD, Calarco JR, Careccia SL, Carman DS, Casey L, Chen S, Cheng L, Clinton E, Cole PL, Collins P, Crabb D, Crannell H, Crede V, Cummings JP, Dale D, Daniel A, Dashyan N, De Masi R, De Sanctis E, Degtyarenko PV, Deur A, Dhamija S, Dharmawardane KV, Dickson R, Djalali C, Dodge GE, Donnelly J, Doughty D, Dugger M, Dzyubak OP, Egiyan H, Egiyan KS, El Fassi L, Elouadrhiri L, Eugenio P, Fedotov G, Fersch R, Forest TA, Fradi A, Gabrielyan MY, Gan L, Garçon M, Gasparian A, Gavalian G, Gevorgyan N, Gilfoyle GP, Giovanetti KL, Girod FX, Glamazdin O, Goett J, Goetz JT, Gohn W, Golovatch E, Gordon CI, Gothe RW, Graham L, Griffioen KA, Guidal M, Guler N, Guo L, Gyurjyan V, Hadjidakis C, Hafidi K, Hakobyan H, Hakobyan RS, Hanretty C, Hardie J, Hassall N, Heddle D, Hersman FW, Hicks K, Hleiqawi I, Holtrop M, Hyde CE, Ilieva Y, Ireland DG, Ishkhanov BS, Isupov EL, Ito MM, Jenkins D, Jo HS, Johnstone JR, Joo K, Juengst HG, Kageya T, Kalantarians N, Keller D, Kellie JD, Khandaker M, Khetarpal P, Kim W, Klein A, Klein FJ, Klimenko AV, Konczykowski P, Kossov M, Krahn Z, Kramer LH, Kubarovsky V, Kuhn J, Kuhn SE, Kuleshov SV, Kuznetsov V, Lachniet J, Laget JM, Langheinrich J, Lawrence D, Lee T, Lesniak L, Li J, Livingston K, Lowry M, Lu HY, Maccormick M, Malace S, Markov N, Mattione P, McCracken ME, McKinnon B, Mecking BA, Melone JJ, Mestayer MD, Meyer CA, Mibe T, Mikhailov K, Mineeva T, Minehart R, Mirazita M, Miskimen R, Mochalov V, Mokeev V, Moreno B, Moriya K, Morrow SA, Moteabbed M, Munevar E, Mutchler GS, Nadel-Turonski P, Nakagawa I, Nasseripour R, Niccolai S, Niculescu G, Niculescu I, Niczyporuk BB, Niroula MR, Niyazov RA, Nozar M, Osipenko M, Ostrovidov AI, Park K, Park S, Pasyuk E, Paris M, Paterson C, Pereira SA, Pierce J, Pivnyuk N, Pocanic D, Pogorelko O, Pozdniakov S, Price JW, Prok Y, Protopopescu D, Raue BA, Riccardi G, Ricco G, Ripani M, Ritchie BG, Rosner G, Rossi P, Sabatié F, Saini MS, Salamanca J, Salgado C, Sandorfi A, Santoro JP, Sapunenko V, Schott D, Schumacher RA, Serov VS, Sharabian YG, Sharov D, Shvedunov NV, Smith ES, Smith LC, Sober DI, Sokhan D, Starostin A, Stavinsky A, Stepanyan S, Stepanyan SS, Stokes BE, Stoler P, Stopani KA, Strakovsky II, Strauch S, Taiuti M, Tedeschi DJ, Teymurazyan A, Tkabladze A, Tkachenko S, Todor L, Tur C, Ungaro M, Vineyard MF, Vlassov AV, Watts DP, Wei X, Weinstein LB, Weygand DP, Williams M, Wolin E, Wood MH, Yegneswaran A, Yurov M, Zana L, Zhang J, Zhao B, and Zhao ZW
Abstract: We report on the results of the first measurement of exclusive f_{0}(980) meson photoproduction on protons for E_{gamma}=3.0-3.8 GeV and -t=0.4-1.0 GeV2. Data were collected with the CLAS detector at the Thomas Jefferson National Accelerator Facility. The resonance was detected via its decay in the pi;{+}pi;{-} channel by performing a partial wave analysis of the reaction gammap-->ppi;{+}pi;{-}. Clear evidence of the f_{0}(980) meson was found in the interference between P and S waves at M_{pi;{+}pi;{-}} approximately 1 GeV. The S-wave differential cross section integrated in the mass range of the f_{0}(980) was found to be a factor of about 50 smaller than the cross section for the rho meson. This is the first time the f_{0}(980) meson has been measured in a photoproduction experiment.
Published: 2009
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42. Search for the photoexcitation of exotic mesons in the pi+pi+pi- system.

Author: Nozar M, Salgado C, Weygand DP, Guo L, Adams G, Li J, Eugenio P, Amaryan MJ, Anghinolfi M, Asryan G, Avakian H, Bagdasaryan H, Baillie N, Ball JP, Baltzell NA, Barrow S, Battaglieri M, Bedlinskiy I, Bektasoglu M, Bellis M, Benmouna N, Berman BL, Biselli AS, Blaszczyk L, Bonner BE, Bouchigny S, Boiarinov S, Bradford R, Branford D, Briscoe WJ, Brooks WK, Bültmann S, Burkert VD, Butuceanu C, Calarco JR, Careccia SL, Carman DS, Carnahan B, Casey L, Cazes A, Chen S, Cheng L, Cole PL, Collins P, Coltharp P, Cords D, Corvisiero P, Crabb D, Crannell H, Crede V, Cummings JP, Dale D, Dashyan N, De Masi R, De Vita R, De Sanctis E, Degtyarenko PV, Denizli H, Dennis L, Deur A, Dharmawardane KV, Dhuga KS, Dickson R, Djalali C, Dodge GE, Doughty D, Dugger M, Dytman S, Dzyubak OP, Egiyan H, Egiyan KS, El Fassi L, Elouadrhiri L, Fatemi R, Fedotov G, Feuerbach RJ, Forest TA, Fradi A, Funsten H, Garçon M, Gavalian G, Gevorgyan N, Gilfoyle GP, Giovanetti KL, Girod FX, Goetz JT, Gothe RW, Griffioen KA, Guidal M, Guillo M, Guler N, Gyurjyan V, Hadjidakis C, Hafidi K, Hakobyan H, Hanretty C, Hardie J, Hassall N, Heddle D, Hersman FW, Hicks K, Hleiqawi I, Holtrop M, Hyde-Wright CE, Ilieva Y, Ireland DG, Ishkhanov BS, Isupov EL, Ito MM, Jenkins D, Jo HS, Johnstone JR, Joo K, Juengst HG, Kalantarians N, Kellie JD, Khandaker M, Kim W, Klein A, Klein FJ, Kossov M, Krahn Z, Kramer LH, Kubarovsky V, Kuhn J, Kuhn SE, Kuleshov SV, Kuznetsov V, Lachniet J, Laget JM, Langheinrich J, Lawrence D, Livingston K, Lu HY, Maccormick M, Markov N, Mattione P, McAleer S, McKinnon B, McNabb JW, Mecking BA, Mehrabyan S, Mestayer MD, Meyer CA, Mibe T, Mikhailov K, Mirazita M, Miskimen R, Mokeev V, Moreno B, Moriya K, Morrow SA, Moteabbed M, Mueller J, Munevar E, Mutchler GS, Nadel-Turonski P, Nasseripour R, Niccolai S, Niculescu G, Niculescu I, Niczyporuk BB, Niroula MR, Niyazov RA, O'Rielly GV, Osipenko M, Ostrovidov AI, Park K, Pasyuk E, Paterson C, Anefalos Pereira S, Philips SA, Pierce J, Pivnyuk N, Pocanic D, Pogorelko O, Polli E, Popa I, Pozdniakov S, Preedom BM, Price JW, Prok Y, Protopopescu D, Qin LM, Raue BA, Riccardi G, Ricco G, Ripani M, Ritchie BG, Ronchetti F, Rosner G, Rossi P, Rubin PD, Sabatié F, Salamanca J, Santoro JP, Sapunenko V, Schumacher RA, Serov VS, Sharabian YG, Sharov D, Shvedunov NV, Skabelin AV, Smith ES, Smith LC, Sober DI, Sokhan D, Stavinsky A, Stepanyan SS, Stepanyan S, Stokes BE, Stoler P, Strakovsky II, Strauch S, Taiuti M, Tedeschi DJ, Thoma U, Tkabladze A, Tkachenko S, Todor L, Ungaro M, Vineyard MF, Vlassov AV, Watts DP, Weinstein LB, Williams M, Wolin E, Wood MH, Yegneswaran A, Zana L, Zhang J, Zhao B, and Zhao ZW
Abstract: A search for exotic mesons in the pi;{+}pi;{+}pi;{-} system photoproduced by the charge exchange reaction gammap-->pi;{+}pi;{+}pi;{-}(n) was carried out by the CLAS Collaboration at Jefferson Lab. A tagged-photon beam with energies in the 4.8 to 5.4 GeV range, produced through bremsstrahlung from a 5.744 GeV electron beam, was incident on a liquid-hydrogen target. A partial wave analysis was performed on a sample of 83 000 events, the highest such statistics to date in this reaction at these energies. The main objective of this study was to look for the photoproduction of an exotic J;{PC}=1;{-+} resonant state in the 1 to 2 GeV mass range. Our partial wave analysis shows production of the a_{2}(1320) and the pi_{2}(1670) mesons, but no evidence for the a_{1}(1260), nor the pi_{1}(1600) exotic state at the expected levels. An upper limit of 13.5 nb is determined for the exotic pi_{1}(1600) cross section, less than 2% of the a_{2}(1320) production.
Published: 2009
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43. Measurement of deeply virtual compton scattering beam-spin asymmetries.

Author: Girod FX, Niyazov RA, Avakian H, Ball J, Bedlinskiy I, Burkert VD, De Masi R, Elouadrhiri L, Garçon M, Guidal M, Jo HS, Joo K, Kubarovsky V, Kuleshov SV, MacCormick M, Niccolai S, Pogorelko O, Sabatié F, Stepanyan S, Stoler P, Ungaro M, Zhao B, Amaryan MJ, Ambrozewicz P, Anghinolfi M, Asryan G, Bagdasaryan H, Baillie N, Ball JP, Baltzell NA, Batourine V, Battaglieri M, Bellis M, Benmouna N, Berman BL, Biselli AS, Blaszczyk L, Bouchigny S, Boiarinov S, Bradford R, Branford D, Briscoe WJ, Brooks WK, Bültmann S, Butuceanu C, Calarco JR, Careccia SL, Carman DS, Casey L, Chen S, Cheng L, Cole PL, Collins P, Coltharp P, Crabb D, Crede V, Dashyan N, De Sanctis E, De Vita R, Degtyarenko PV, Deur A, Dharmawardane KV, Dickson R, Djalali C, Dodge GE, Donnelly J, Doughty D, Dugger M, Dzyubak OP, Egiyan H, Egiyan KS, El Fassi L, Eugenio P, Fedotov G, Feldman G, Funsten H, Gavalian G, Gilfoyle GP, Giovanetti KL, Goetz JT, Gonenc A, Gothe RW, Griffioen KA, Guler N, Guo L, Gyurjyan V, Hafidi K, Hakobyan H, Hanretty C, Hersman FW, Hicks K, Hleiqawi I, Holtrop M, Hyde CE, Ilieva Y, Ireland DG, Ishkhanov BS, Isupov EL, Ito MM, Jenkins D, Johnstone JR, Juengst HG, Kalantarians N, Kellie JD, Khandaker M, Kim W, Klein A, Klein FJ, Klimenko AV, Kossov M, Krahn Z, Kramer LH, Kuhn J, Kuhn SE, Lachniet J, Laget JM, Langheinrich J, Lawrence D, Lee T, Livingston K, Lu HY, Markov N, Mattione P, Mazouz M, McKinnon B, Mecking BA, Mestayer MD, Meyer CA, Mibe T, Michel B, Mikhailov K, Mirazita M, Miskimen R, Mokeev V, Moriya K, Morrow SA, Moteabbed M, Munevar E, Mutchler GS, Nadel-Turonski P, Nasseripour R, Niculescu G, Niculescu I, Niczyporuk BB, Niroula MR, Nozar M, Osipenko M, Ostrovidov AI, Park K, Pasyuk E, Paterson C, Anefalos Pereira S, Pierce J, Pivnyuk N, Pocanic D, Pozdniakov S, Price JW, Procureur S, Prok Y, Protopopescu D, Raue BA, Ricco G, Ripani M, Ritchie BG, Rosner G, Rossi P, Salamanca J, Salgado C, Santoro JP, Sapunenko V, Schumacher RA, Serov VS, Sharabian YG, Sharov D, Shvedunov NV, Smith ES, Smith LC, Sober DI, Sokhan D, Stavinsky A, Stepanyan SS, Stokes BE, Strakovsky II, Strauch S, Taiuti M, Tedeschi DJ, Tkabladze A, Tkachenko S, Tur C, Vineyard MF, Vlassov AV, Voutier E, Watts DP, Weinstein LB, Weygand DP, Williams M, Wolin E, Wood MH, Yegneswaran A, Zana L, Zhang J, and Zhao ZW
Abstract: The beam-spin asymmetries in the hard exclusive electroproduction of photons on the proton (e p-->epgamma) were measured over a wide kinematic range and with high statistical accuracy. These asymmetries result from the interference of the Bethe-Heitler process and of deeply virtual Compton scattering. Over the whole kinematic range (x(B) from 0.11 to 0.58, Q2 from 1 to 4.8 GeV2, -t from 0.09 to 1.8 GeV2), the azimuthal dependence of the asymmetries is compatible with expectations from leading-twist dominance, A approximately a sinphi/(1+c cosphi). This extensive set of data can thus be used to constrain significantly the generalized parton distributions of the nucleon in the valence quark sector.
Published: 2008
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44. Search for medium modifications of the rho meson.

Author: Nasseripour R, Wood MH, Djalali C, Weygand DP, Tur C, Mosel U, Muehlich P, Adams G, Amaryan MJ, Ambrozewicz P, Anghinolfi M, Asryan G, Avakian H, Bagdasaryan H, Baillie N, Ball JP, Baltzell NA, Barrow S, Battaglieri M, Bedlinskiy I, Bektasoglu M, Bellis M, Benmouna N, Berman BL, Biselli AS, Blaszczyk L, Bouchigny S, Boiarinov S, Bradford R, Branford D, Briscoe WJ, Brooks WK, Bültmann S, Burkert VD, Butuceanu C, Calarco JR, Careccia SL, Carman DS, Carnahan B, Casey L, Chen S, Cole PL, Collins P, Coltharp P, Crabb D, Crannell H, Crede V, Cummings JP, Dashyan N, De Masi R, De Vita R, De Sanctis E, Degtyarenko PV, Denizli H, Dennis L, Deur A, Dharmawardane KV, Dickson R, Dodge GE, Doughty D, Dugger M, Dytman S, Dzyubak OP, Egiyan H, Egiyan KS, El Fassi L, Elouadrhiri L, Eugenio P, Fedotov G, Feldman G, Feuerbach RJ, Funsten H, Garçon M, Gavalian G, Gilfoyle GP, Giovanetti KL, Girod FX, Goetz JT, Gordon CI, Gothe RW, Griffioen KA, Guidal M, Guler N, Guo L, Gyurjyan V, Hadjidakis C, Hafidi K, Hakobyan H, Hakobyan RS, Hanretty C, Hardie J, Hersman FW, Hicks K, Hleiqawi I, Holtrop M, Hyde-Wright CE, Ilieva Y, Ireland DG, Ishkhanov BS, Isupov EL, Ito MM, Jenkins D, Jo HS, Johnstone JR, Joo K, Juengst HG, Kalantarians N, Kellie JD, Khandaker M, Kim W, Klein A, Klein FJ, Klimenko AV, Kossov M, Krahn Z, Kramer LH, Kubarovsky V, Kuhn J, Kuhn SE, Kuleshov SV, Lachniet J, Laget JM, Langheinrich J, Lawrence D, Li J, Livingston K, Lu HY, Maccormick M, Markov N, Mattione P, McAleer S, McKinnon B, McNabb JW, Mecking BA, Mehrabyan S, Melone JJ, Mestayer MD, Meyer CA, Mibe T, Mikhailov K, Minehart R, Mirazita M, Miskimen R, Mokeev V, Moriya K, Morrow SA, Moteabbed M, Mueller J, Munevar E, Mutchler GS, Nadel-Turonski P, Niccolai S, Niculescu G, Niculescu I, Niczyporuk BB, Niroula MR, Niyazov RA, Nozar M, Osipenko M, Ostrovidov AI, Park K, Pasyuk E, Paterson C, Anefalos Pereira S, Pierce J, Pivnyuk N, Pocanic D, Pogorelko O, Pozdniakov S, Preedom BM, Price JW, Prok Y, Protopopescu D, Raue BA, Riccardi G, Ricco G, Ripani M, Ritchie BG, Ronchetti F, Rosner G, Rossi P, Sabatié F, Salamanca J, Salgado C, Santoro JP, Sapunenko V, Schumacher RA, Serov VS, Sharabian YG, Sharov D, Shvedunov NV, Smith ES, Smith LC, Sober DI, Sokhan D, Stavinsky A, Stepanyan SS, Stepanyan S, Stokes BE, Stoler P, Strakovsky II, Strauch S, Taiuti M, Tedeschi DJ, Tkabladze A, Tkachenko S, Todor L, Ungaro M, Vineyard MF, Vlassov AV, Watts DP, Weinstein LB, Williams M, Wolin E, Yegneswaran A, Zana L, Zhang B, Zhang J, Zhao B, and Zhao ZW
Abstract: The photoproduction of vector mesons on various nuclei has been studied using the CLAS detector at Jefferson Laboratory. The vector mesons, rho, omega, and varphi, are observed via their decay to e;{+}e;{-}, in order to reduce the effects of final-state interactions in the nucleus. Of particular interest are possible in-medium effects on the properties of the rho meson. The rho mass spectrum is extracted from the data on various nuclei, 2H, C, Fe, and Ti. We observe no significant mass shift and some broadening consistent with expected collisional broadening for the rho meson.
Published: 2007
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45. Experimental study of exclusive 2H(e,e'p)n reaction mechanisms at high Q2.

Author: Egiyan KS, Asryan G, Gevorgyan N, Griffioen KA, Laget JM, Kuhn SE, Adams G, Amaryan MJ, Ambrozewicz P, Anghinolfi M, Audit G, Avakian H, Bagdasaryan H, Baillie N, Ball JP, Baltzell NA, Barrow S, Batourine V, Battaglieri M, Bedlinskiy I, Bektasoglu M, Bellis M, Benmouna N, Berman BL, Biselli AS, Blaszczyk L, Bouchigny S, Boiarinov S, Bradford R, Branford D, Briscoe WJ, Brooks WK, Bültmann S, Burkert VD, Butuceanu C, Calarco JR, Careccia SL, Carman DS, Cazes A, Chen S, Cole PL, Collins P, Coltharp P, Cords D, Corvisiero P, Crabb D, Crede V, Cummings JP, Dashyan N, De Masi R, De Vita R, De Sanctis E, Degtyarenko PV, Denizli H, Dennis L, Deur A, Dharmawardane KV, Dickson R, Djalali C, Dodge GE, Donnelly J, Doughty D, Dugger M, Dytman S, Dzyubak OP, Egiyan H, El Fassi L, Elouadrhiri L, Eugenio P, Fatemi R, Fedotov G, Feldman G, Feuerbach RJ, Fersch R, Garçon M, Gavalian G, Gilfoyle GP, Giovanetti KL, Girod FX, Goetz JT, Gonenc A, Gordon CI, Gothe RW, Guidal M, Guillo M, Guler N, Guo L, Gyurjyan V, Hadjidakis C, Hafidi K, Hakobyan H, Hakobyan RS, Hanretty C, Hardie J, Hersman FW, Hicks K, Hleiqawi I, Holtrop M, Hyde-Wright CE, Ilieva Y, Ireland DG, Ishkhanov BS, Isupov EL, Ito MM, Jenkins D, Jo HS, Joo K, Juengst HG, Kalantarians N, Kellie JD, Khandaker M, Kim W, Klein A, Klein FJ, Klimenko AV, Kossov M, Krahn Z, Kramer LH, Kubarovsky V, Kuhn J, Kuleshov SV, Lachniet J, Langheinrich J, Lawrence D, Li J, Livingston K, Lu HY, Maccormick M, Marchand C, Markov N, Mattione P, McAleer S, McKinnon B, McNabb JW, Mecking BA, Mehrabyan S, Melone JJ, Mestayer MD, Meyer CA, Mibe T, Mikhailov K, Minehart R, Mirazita M, Miskimen R, Mokeev V, Moriya K, Morrow SA, Moteabbed M, Mueller J, Munevar E, Mutchler GS, Nadel-Turonski P, Nasseripour R, Niccolai S, Niculescu G, Niculescu I, Niczyporuk BB, Niroula MR, Niyazov RA, Nozar M, O'Rielly GV, Osipenko M, Ostrovidov AI, Park K, Pasyuk E, Paterson C, Anefalos Pereira S, Pierce J, Pivnyuk N, Pocanic D, Pogorelko O, Pozdniakov S, Preedom BM, Price JW, Prok Y, Protopopescu D, Raue BA, Riccardi G, Ricco G, Ripani M, Ritchie BG, Ronchetti F, Rosner G, Rossi P, Sabatié F, Salamanca J, Salgado C, Santoro JP, Sapunenko V, Schumacher RA, Serov VS, Sharabian YG, Shvedunov NV, Skabelin AV, Smith ES, Smith LC, Sober DI, Sokhan D, Stavinsky A, Stepanyan SS, Stepanyan S, Stokes BE, Stoler P, Strauch S, Taiuti M, Tedeschi DJ, Thoma U, Tkabladze A, Tkachenko S, Todor L, Tur C, Ungaro M, Vineyard MF, Vlassov AV, Watts DP, Weinstein LB, Weygand DP, Williams M, Wolin E, Wood MH, Yegneswaran A, Zana L, Zhang J, Zhao B, and Zhao ZW
Abstract: The reaction 2H(e,e'p)n has been studied with full kinematic coverage for photon virtuality 1.75NN transition is the primary contribution at higher momenta.
Published: 2007
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46. Measurement of the N-->Delta(+)(1232) transition at high-momentum transfer by pi(0) electroproduction.

Author: Ungaro M, Stoler P, Aznauryan I, Burkert VD, Joo K, Smith LC, Adams G, Amarian M, Ambrozewicz P, Anghinolfi M, Asryan G, Audit G, Avakian H, Bagdasaryan H, Ball JP, Baltzell NA, Barrow S, Batourine V, Battaglieri M, Bedliski I, Bektasoglu M, Bellis M, Benmouna N, Berman BL, Biselli AS, Bonner BE, Bouchigny S, Boiarinov S, Bradford R, Branford D, Briscoe WJ, Brooks WK, Bültmann S, Butuceanu C, Calarco JR, Careccia SL, Carman DS, Cazes A, Chen S, Cole PL, Coltharp P, Cords D, Corvisiero P, Crabb D, Cummings JP, Sanctis ED, Devita R, Degtyarenko PV, Denizli H, Dennis L, Deur A, Dharmawardane KV, Djalali C, Dodge GE, Donnelly J, Doughty D, Dugger M, Dytman S, Dzyubak OP, Egiyan H, Egiyan KS, Elouadrhiri L, Eugenio P, Fatemi R, Fedotov G, Feldman G, Feuerbach RJ, Funsten H, Garçon M, Gavalian G, Gilfoyle GP, Giovanetti KL, Girod FX, Goetz J, Gordon CI, Gothe RW, Griffioen KA, Guidal M, Guillo M, Guler N, Guo L, Gyurjyan V, Hadjidakis C, Hakobyan RS, Hardie J, Heddle D, Hersman FW, Hleiqawi I, Holtrop M, Hicks K, Hyde-Wright CE, Ilieva Y, Ireland DG, Ishkhanov BS, Ito MM, Jenkins D, Jo HS, Juengst HG, Kellie JD, Khandaker M, Kim W, Klein A, Klein FJ, Klimenko AV, Kossov M, Kramer LH, Kubarovsky V, Kuhn J, Kuhn SE, Lachniet J, Laget JM, Langheinrich J, Lawrence D, Lee T, Li J, Livingston K, Marchand C, Markov N, McAleer S, McKinnon B, McNabb JW, Mecking BA, Mehrabyan S, Melone JJ, Mestayer MD, Meyer CA, Mikhailov K, Minehart R, Mirazita M, Miskimen R, Mokeev V, Morand L, Morrow SA, Mueller J, Mutchler GS, Napolitano J, Nasseripour R, Niccolai S, Niculescu G, Niculescu I, Niczyporuk BB, Niroula M, Niyazov RA, Nozar M, O'rielly GV, Osipenko M, Ostrovidov AI, Park K, Pasyuk E, Philips SA, Pivnyuk N, Pocanic D, Pogorelko O, Polli E, Pozdniakov S, Preedom BM, Price JW, Prok Y, Protopopescu D, Qin LM, Raue BA, Riccardi G, Ricco G, Ripani M, Ritchie BG, Ronchetti F, Rosner G, Rossi P, Rubin PD, Sabatié F, Salgado C, Santoro JP, Sapunenko V, Schumacher RA, Serov VS, Sharabian YG, Skabelin AV, Smith ES, Sober DI, Stavinsky A, Stepanyan SS, Stepanyan S, Stokes BE, Strakovsky II, Strauch S, Taiuti M, Tedeschi DJ, Thoma U, Tkabladze A, Todor L, Tkachenko S, Tur C, Vineyard MF, Vlassov AV, Weinstein LB, Weygand DP, Williams M, Wolin E, Wood MH, Yegneswaran A, Zana L, Zhang B, Zhang J, and Zhao B
Abstract: We report a new measurement of the exclusive electroproduction reaction gamma(*)p-->pi(0)p to explore the evolution from soft nonperturbative physics to hard processes via the Q(2) dependence of the magnetic (M(1+)), electric (E(1+)), and scalar (S(1+)) multipoles in the N-->Delta transition. 9000 differential cross section data points cover W from threshold to 1.4 GeV/c(2), 4pi center-of-mass solid angle, and Q(2) from 3 to 6 GeV(2)/c(2), the highest yet achieved. It is found that the magnetic form factor G(M)(*) decreases with Q(2) more steeply than the proton magnetic form factor, the ratio E(1+)/M(1+) is small and negative, indicating strong helicity nonconservation, and the ratio S(1+)/M(1+) is negative, while its magnitude increases with Q(2).
Published: 2006
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47. Search for Theta++ pentaquarks in the exclusive reaction gammap-->K+K-p.

Author: Kubarovsky V, Battaglieri M, De Vita R, Goett J, Guo L, Mutchler GS, Stoler P, Weygand DP, Ambrozewicz P, Anghinolfi M, Asryan G, Avakian H, Bagdasaryan H, Baillie N, Ball JP, Baltzell NA, Batourine V, Bedlinskiy I, Bellis M, Benmouna N, Berman BL, Biselli AS, Bouchigny S, Boiarinov S, Bradford R, Branford D, Briscoe WJ, Brooks WK, Bültmann S, Burkert VD, Butuceanu C, Calarco JR, Careccia SL, Carman DS, Chen S, Clinton E, Cole PL, Collins P, Coltharp P, Crabb D, Crannell H, Crede V, Cummings JP, De Masi R, Dale D, De Sanctis E, Degtyarenko PV, Deur A, Dharmawardane KV, Djalali C, Dodge GE, Donnelly J, Doughty D, Dugger M, Dzyubak OP, Egiyan H, Egiyan KS, Elouadrhiri L, Eugenio P, Fedotov G, Funsten H, Gabrielyan MY, Gan L, Garçon M, Gasparian A, Gavalian G, Gilfoyle GP, Giovanetti KL, Girod FX, Glamazdin O, Goetz JT, Golovach E, Gonenc A, Gordon CI, Gothe RW, Griffioen KA, Guidal M, Guler N, Gyurjyan V, Hadjidakis C, Hafidi K, Hakobyan RS, Hardie J, Hersman FW, Hicks K, Hleiqawi I, Holtrop M, Hyde-Wright CE, Ilieva Y, Ireland DG, Ishkhanov BS, Isupov EL, Ito MM, Jenkins D, Jo HS, Joo K, Juengst HG, Kellie JD, Khandaker M, Kim W, Klein A, Klein FJ, Klimenko AV, Kossov M, Kramer LH, Kuhn J, Kuhn SE, Kuleshov SV, Lachniet J, Laget JM, Langheinrich J, Lawrence D, Lee T, Li J, Livingston K, Lu H, MacCormick M, Markov N, McKinnon B, Mecking BA, Melone JJ, Mestayer MD, Meyer CA, Mibe T, Mikhailov K, Minehart R, Mirazita M, Miskimen R, Mochalov V, Mokeev V, Morand L, Morrow SA, Moteabbed M, Nadel-Turonski P, Nakagawa I, Nasseripour R, Niccolai S, Niculescu G, Niculescu I, Niczyporuk BB, Niroula MR, Niyazov RA, Nozar M, Osipenko M, Ostrovidov AI, Park K, Pasyuk E, Paterson C, Pierce J, Pivnyuk N, Pocanic D, Pogorelko O, Pozdniakov S, Price JW, Prok Y, Protopopescu D, Raue BA, Riccardi G, Ricco G, Ripani M, Ritchie BG, Ronchetti F, Rosner G, Rossi P, Sabatié F, Salgado C, Santoro JP, Sapunenko V, Schumacher RA, Serov VS, Sharabian YG, Shvedunov NV, Smith ES, Smith LC, Sober DI, Stavinsky A, Stepanyan SS, Stepanyan S, Stokes BE, Strakovsky II, Strauch S, Taiuti M, Tedeschi DJ, Teymurazyan A, Thoma U, Tkabladze A, Tkachenko S, Todor L, Tur C, Ungaro M, Vineyard MF, Vlassov AV, Weinstein LB, Williams M, Wolin E, Wood MH, Yegneswaran A, Zana L, Zhang J, and Zhao B
Abstract: The reaction gammap --> pK+K- was studied at Jefferson Lab with photon energies from 1.8 to 3.8 GeV using a tagged photon beam. The goal was to search for a Theta++ pentaquark, a narrow, doubly charged baryon state having strangeness S=+1 and isospin I=1, in the pK+ invariant mass spectrum. No statistically significant evidence of a Theta++ was found. Upper limits on the total and differential cross section for the reaction gammap --> K-Theta++ were obtained in the mass range from 1.5 to 2.0 GeV/c2, with an upper limit for a narrow resonance with a mass M(Theta++) = 1.54 GeV/c2 of about 0.15 nb, 95% C.L.. This result places a stringent upper limit on the Theta++ width Gamma(Theta++) <0.1 MeV/c2.
Published: 2006
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48. Measurement of deeply virtual compton scattering with a polarized-proton target.

Author: Chen S, Avakian H, Burkert VD, Eugenio P, Adams G, Amarian M, Ambrozewicz P, Anghinolfi M, Asryan G, Bagdasaryan H, Baillie N, Ball JP, Baltzell NA, Barrow S, Batourine V, Battaglieri M, Beard K, Bedlinskiy I, Bektasoglu M, Bellis M, Benmouna N, Berman BL, Biselli AS, Bonner BE, Bouchigny S, Boiarinov S, Bosted P, Bradford R, Branford D, Briscoe WJ, Brooks WK, Bültmann S, Butuceanu C, Calarco JR, Careccia SL, Carman DS, Carnahan B, Cazes A, Cole PL, Collins P, Coltharp P, Cords D, Corvisiero P, Crabb D, Crannell H, Crede V, Cummings JP, DeMasi R, DeVita R, De Sanctis E, Degtyarenko PV, Denizli H, Dennis L, Deur A, Dharmawardane KV, Dhuga KS, Djalali C, Dodge GE, Donnelly J, Doughty D, Dugger M, Dytman S, Dzyubak OP, Egiyan H, Egiyan KS, El Fassi L, Elouadrhiri L, Fatemi R, Fedotov G, Feldman G, Feuerbach RJ, Forest TA, Funsten H, Garçon M, Gavalian G, Gilfoyle GP, Giovanetti KL, Girod FX, Goetz JT, Golovatch E, Gonenc A, Gothe RW, Griffioen KA, Guidal M, Guillo M, Guler N, Guo L, Gyurjyan V, Hadjidakis C, Hafidi K, Hakobyan H, Hakobyan RS, Hardie J, Heddle D, Hersman FW, Hicks K, Hleiqawi I, Holtrop M, Huertas M, Hyde-Wright CE, Ilieva Y, Ireland DG, Ishkhanov BS, Isupov EL, Ito MM, Jenkins D, Jo HS, Joo K, Juengst HG, Keith C, Kellie JD, Khandaker M, Kim KY, Kim K, Kim W, Klein A, Klein FJ, Klusman M, Kossov M, Kramer LH, Kubarovsky V, Kuhn J, Kuhn SE, Kuleshov SV, Lachniet J, Laget JM, Langheinrich J, Lawrence D, Li J, Lima AC, Livingston K, Lu H, Lukashin K, MacCormick M, Markov N, McAleer S, McKinnon B, McNabb JW, Mecking BA, Mestayer MD, Meyer CA, Mibe T, Mikhailov K, Minehart R, Mirazita M, Miskimen R, Mokeev V, Morand L, Morrow SA, Moteabbed M, Mueller J, Mutchler GS, Nadel-Turonski P, Napolitano J, Nasseripour R, Natasha N, Niccolai S, Niculescu G, Niculescu I, Niczyporuk BB, Niroula MR, Niyazov RA, Nozar M, O'Rielly GV, Osipenko M, Ostrovidov AI, Park K, Pasyuk E, Paterson C, Philips SA, Pierce J, Pivnyuk N, Pocanic D, Pogorelko O, Polli E, Popa I, Pozdniakov S, Preedom BM, Price JW, Prok Y, Protopopescu D, Qin LM, Raue BA, Riccardi G, Ricco G, Ripani M, Ritchie BG, Ronchetti F, Rosner G, Rossi P, Rowntree D, Rubin PD, Sabatié F, Salgado C, Santoro JP, Sapunenko V, Schumacher RA, Serov VS, Sharabian YG, Shaw J, Shvedunov NV, Skabelin AV, Smith ES, Smith LC, Sober DI, Stavinsky A, Stepanyan SS, Stepanyan S, Stokes BE, Stoler P, Strakovsky II, Strauch S, Suleiman R, Taiuti M, Tedeschi DJ, Thoma U, Tkabladze A, Tkachenko S, Todor L, Tur C, Ungaro M, Vanderhaeghen M, Vineyard MF, Vlassov AV, Watts DP, Weinstein LB, Weygand DP, Williams M, Wolin E, Wood MH, Yegneswaran A, Yun J, Zana L, Zhang J, Zhao B, and Zhao Z
Abstract: The longitudinal target-spin asymmetry AUL for the exclusive electroproduction of high-energy photons was measured for the first time in ep-->e;'pgamma. The data have been accumulated at JLab with the CLAS spectrometer using 5.7 GeV electrons and a longitudinally polarized NH3 target. A significant azimuthal angular dependence was observed, resulting from the interference of the deeply virtual Compton scattering and Bethe-Heitler processes. The amplitude of the sinvarphi moment is 0.252+/-0.042stat+/-0.020sys. Theoretical calculations are in good agreement with the magnitude and the kinematic dependence of the target-spin asymmetry, which is sensitive to the generalized parton distributions H and H.
Published: 2006
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49. Search for the Theta+ Pentaquark in the gammad--> DeltanK+ reaction measured with the CLAS spectrometer.

Author: Niccolai S, Mirazita M, Rossi P, Baltzell NA, Carman DS, Hicks K, McKinnon B, Mibe T, Stepanyan S, Tedeschi DJ, Adams G, Ambrozewicz P, Anefalos Pereira S, Anghinolfi M, Asryan G, Avakian H, Bagdasaryan H, Baillie N, Ball JP, Batourine V, Battaglieri M, Bedlinskiy I, Bektasoglu M, Bellis M, Benmouna N, Berman BL, Biselli AS, Boiarinov S, Bouchigny S, Bradford R, Branford D, Briscoe WJ, Brooks WK, Bültmann S, Burkert VD, Butuceanu C, Calarco JR, Careccia SL, Carnahan B, Chen S, Cole PL, Collins P, Coltharp P, Crabb D, Crannell H, Crede V, Cummings JP, Dashyan N, Degtyarenko PV, De Masi R, Deppman A, De Sanctis E, Deur A, Devita R, Dharmawardane KV, Djalali C, Dodge GE, Donnelly J, Doughty D, Dugger M, Dzyubak OP, Egiyan H, Egiyan KS, El Fassi L, Elouadrhiri L, Eugenio P, Fedotov G, Feldman G, Funsten H, Garçon M, Gavalian G, Gilfoyle GP, Giovanetti KL, Girod FX, Goetz JT, Gonenc A, Gordon CI, Gothe RW, Griffioen KA, Guidal M, Guler N, Guo L, Gyurjyan V, Hadjidakis C, Hafidi K, Hakobyan H, Hakobyan RS, Hardie J, Hersman FW, Hleiqawi I, Holtrop M, Hyde-Wright CE, Ilieva Y, Ireland DG, Ishkhanov BS, Isupov EL, Ito MM, Jenkins D, Jo HS, Joo K, Juengst HG, Kellie JD, Khandaker M, Kim W, Klein A, Klein FJ, Klimenko AV, Kossov M, Kramer LH, Kubarovsky V, Kuhn J, Kuhn SE, Kuleshov SV, Lachniet J, Langheinrich J, Lawrence D, Lee T, Li J, Livingston K, Lu H, MacCormick M, Markov N, Mecking BA, Mellor J, Melone JJ, Mestayer MD, Meyer CA, Mikhailov K, Minehart R, Miskimen R, Mokeev V, Morand L, Morrow SA, Moteabbed M, Mutchler GS, Nadel-Turonski P, Napolitano J, Nasseripour R, Niculescu G, Niculescu I, Niczyporuk BB, Niroula MR, Niyazov RA, Nozar M, de Oliveira Echeimberg J, Osipenko M, Ostrovidov AI, Park K, Pasyuk E, Paterson C, Pierce J, Pivnyuk N, Pocanic D, Pogorelko O, Pozdniakov S, Preedom BM, Price JW, Prok Y, Protopopescu D, Raue BA, Riccardi G, Ricco G, Ripani M, Ritchie BG, Ronchetti F, Rosner G, Sabatié F, Salgado C, Santoro JP, Sapunenko V, Schumacher RA, Serov VS, Sharabian YG, Shvedunov NV, Smith ES, Smith LC, Sober DI, Stavinsky A, Stepanyan SS, Stokes BE, Stoler P, Strakovsky II, Strauch S, Taiuti M, Thoma U, Tkabladze A, Tkachenko S, Todor L, Tur C, Ungaro M, Vineyard MF, Vlassov AV, Watts DP, Weinstein LB, Weygand DP, Williams M, Wolin E, Wood MH, Yegneswaran A, Zana L, Zhang J, Zhao B, and Zhao Z
Abstract: For the first time, the reaction gammad-->DeltanK+ has been analyzed in order to search for the exotic pentaquark baryon Theta+(1540). The data were taken at Jefferson Laboratory, using the Hall-B tagged-photon beam of energy between 0.8 and 3.6 GeV and the CEBAF Large Acceptance Spectrometer (CLAS). No statistically significant structures were observed in the nK+ invariant-mass distribution. The upper limit on the gammad-->DeltaTheta+ integrated cross section has been calculated and found to be between 5 and 25 nb, depending on the production model assumed. The upper limit on the differential cross section is also reported.
Published: 2006
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50. Search for the Theta+ pentaquark in the reaction gammad --> pK-K+n.

Author: McKinnon B, Hicks K, Baltzell NA, Carman DS, Mestayer MD, Mibe T, Mirazita M, Niccolai S, Rossi P, Stepanyan S, Tedeschi DJ, Ambrozewicz P, Anghinolfi M, Asryan G, Avakian H, Bagdasaryan H, Baillie N, Ball JP, Batourine V, Battaglieri M, Bedlinskiy I, Bellis M, Benmouna N, Berman BL, Biselli AS, Bouchigny S, Boiarinov S, Bradford R, Branford D, Briscoe WJ, Brooks WK, Bültmann S, Burkert VD, Butuceanu C, Calarco JR, Careccia SL, Chen S, Cole PL, Collins P, Coltharp P, Crabb D, Crede V, Dale D, De Masi R, DeVita R, De Sanctis E, Degtyarenko PV, Deur A, Djalali C, Dodge GE, Donnelly J, Doughty D, Dugger M, Dzyubak OP, Egiyan H, Egiyan KS, Elouadrhiri L, Eugenio P, Fedotov G, Feldman G, Funsten H, Gabrielyan M, Gan L, Garçon M, Gasparian A, Gavalian G, Gilfoyle GP, Giovanetti KL, Girod FX, Goetz JT, Gonenc A, Gothe RW, Griffioen KA, Guidal M, Guler N, Guo L, Gyurjyan V, Hakobyan RS, Hersman FW, Hleiqawi I, Holtrop M, Hyde-Wright CE, Ilieva Y, Ireland DG, Ishkhanov BS, Ito MM, Jenkins D, Jo HS, Joo K, Juengst HG, Kellie JD, Khandaker M, Kim W, Klein A, Klein FJ, Kossov M, Kramer LH, Kubarovsky V, Kuhn J, Kuhn SE, Kuleshov SV, Lachniet J, Langheinrich J, Lawrence D, Livingston K, Lu H, MacCormick M, Mecking BA, Meyer CA, Mikhailov K, Miskimen R, Mokeev V, Morrow SA, Moteabbed M, Mutchler GS, Nakagawa I, Nadel-Turonski P, Nasseripour R, Niculescu G, Niculescu I, Niczyporuk BB, Niroula MR, Niyazov RA, Nozar M, Osipenko M, Ostrovidov AI, Park K, Pasyuk E, Paterson C, Pierce J, Pivnyuk N, Pogorelko O, Pozdniakov S, Price JW, Prok Y, Protopopescu D, Raue BA, Ricco G, Ripani M, Ritchie BG, Ronchetti F, Rosner G, Sabatié F, Salgado C, Santoro JP, Sapunenko V, Schumacher RA, Serov VS, Sharabian YG, Smith ES, Smith LC, Sober DI, Stavinsky A, Stepanyan SS, Stokes BE, Stoler P, Strakovsky II, Strauch S, Taiuti M, Teymurazyan A, Thoma U, Tkabladze A, Tkachenko S, Tur C, Ungaro M, Vineyard MF, Vlassov AV, Weinstein LB, Weygand DP, Williams M, Wolin E, Wood MH, Yegneswaran A, Zana L, Zhang J, Zhao B, and Zhao Z
Abstract: A search for the Theta+ in the reaction gammad --> pK-K+n was completed using the CLAS detector at Jefferson Lab. A study of the same reaction, published earlier, reported the observation of a narrow Theta+ resonance. The present experiment, with more than 30 times the integrated luminosity of our earlier measurement, does not show any evidence for a narrow pentaquark resonance. The angle-integrated upper limit on Theta+ production in the mass range of 1.52-1.56 GeV/c2 for the gammad --> pK-Theta+ reaction is 0.3 nb (95% C.L.). This upper limit depends on assumptions made for the mass and angular distribution of Theta+ production. Using Lambda(1520) production as an empirical measure of rescattering in the deuteron, the cross section upper limit for the elementary gamman --> K-Theta+ reaction is estimated to be a factor of 10 higher, i.e., approximately 3 nb (95% C.L.).
Published: 2006
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