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Title: Exclusive photoproduction of π 0 up to large values of Mandelstam variables s , t , and u with CLAS

Exclusive photoproduction cross sections have been measured for the process $$\gamma p \rightarrow p\pi^0(e^+e^-(\gamma))$$ with the Dalitz decay final state using tagged photon energies in the range of $$E_{\gamma} = 1.275-5.425$$ GeV. The complete angular distribution of the final state $$\pi^0$$, for the entire photon energy range up to large values of $t$ and $u$, has been measured for the first time. The data obtained show that the cross section $$d\sigma/dt$$, at mid to large angles, decreases with energy as $$s^{-6.89\pm 0.26} $$. This is in agreement with the perturbative QCD quark counting rule prediction of $$s^{-7} $$. Paradoxically, the size of angular distribution of measured cross sections is greatly underestimated by the QCD based Generalized Parton Distribution mechanism at highest available invariant energy $s=11$ GeV$^2$. At the same time, the Regge-exchange-based models for $$\pi^0$$ photoproduction are more consistent with experimental data.
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Publication Date:
Report Number(s):
JLAB-PHY-18-2673; DOE/OR/23177-4403; arXiv:1712.10314
Journal ID: ISSN 2469-9985
Grant/Contract Number:
AC05-06OR23177; SC0016583
Type:
Published Article
Journal Name:
Physical Review C
Additional Journal Information:
Journal Volume: 98; Journal Issue: 1; Journal ID: ISSN 2469-9985
Publisher:
American Physical Society (APS)
Research Org:
Thomas Jefferson National Accelerator Facility (TJNAF), Newport News, VA (United States); George Washington Univ., Washington, DC (United States)
Sponsoring Org:
USDOE Office of Science (SC), Nuclear Physics (NP) (SC-26)
Contributing Orgs:
CLAS Collaboration
Country of Publication:
United States
Language:
English
Subject:
73 NUCLEAR PHYSICS AND RADIATION PHYSICS; 72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS; nuclear structure & decays; particle interactions
OSTI Identifier:
1461599
Alternate Identifier(s):
OSTI ID: 1461455; OSTI ID: 1462020; OSTI ID: 1464055

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., Bültmann, 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., Sabatié, F., Salgado, C., Schadmand, S., Schumacher, R. A., Sharabian, Y. G., Skorodumina, Iu., Stepanyan, S., Ireland, D. G., 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.. Exclusive photoproduction of π0 up to large values of Mandelstam variables s,t, and u with CLAS. United States: N. p., Web. doi:10.1103/PhysRevC.98.015207.
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., Bültmann, 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., Sabatié, F., Salgado, C., Schadmand, S., Schumacher, R. A., Sharabian, Y. G., Skorodumina, Iu., Stepanyan, S., Ireland, D. G., 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., & Zhao, Z. W.. Exclusive photoproduction of π0 up to large values of Mandelstam variables s,t, and u with CLAS. United States. doi:10.1103/PhysRevC.98.015207.
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., Bültmann, 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., Sabatié, F., Salgado, C., Schadmand, S., Schumacher, R. A., Sharabian, Y. G., Skorodumina, Iu., Stepanyan, S., Ireland, D. G., 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.. 2018. "Exclusive photoproduction of π0 up to large values of Mandelstam variables s,t, and u with CLAS". United States. doi:10.1103/PhysRevC.98.015207.
@article{osti_1461599,
title = {Exclusive photoproduction of π0 up to large values of Mandelstam variables s,t, and u with CLAS},
author = {Kunkel, M. C. and Amaryan, M. J. and Strakovsky, I. I. and Ritman, J. and Goldstein, G. R. and Adhikari, K. P. and Adhikari, S. and Avakian, H. and Ball, J. and Balossino, I. and Barion, L. and Battaglieri, M. and Batourine, V. and Bedlinskiy, I. and Biselli, A. S. and Boiarinov, S. and Briscoe, W. J. and Brooks, W. K. and Bültmann, S. and Burkert, V. D. and Cao, F. and Carman, D. S. and Celentano, A. and Charles, G. and Chetry, T. and Ciullo, G. and Clark, L. and Cole, P. L. and Contalbrigo, M. and Cortes, O. and Crede, V. and D'Angelo, A. and Dashyan, N. and De Vita, R. and De Sanctis, E. and Degtyarenko, P. V. and Defurne, M. and Deur, A. and Djalali, C. and Dugger, M. and Dupre, R. and Egiyan, H. and El Alaoui, A. and El Fassi, L. and Elouadrhiri, L. and Eugenio, P. and Fedotov, G. and Fersch, R. and Filippi, A. and Fradi, A. and Gavalian, G. and Ghandilyan, Y. and Ghosh, S. and Gilfoyle, G. P. and Giovanetti, K. L. and Girod, F. X. and Glazier, D. I. and Gohn, W. and Golovatch, E. and Gothe, R. W. and Griffioen, K. A. and Guo, L. and Guidal, M. and Hafidi, K. and Hakobyan, H. and Harrison, N. and Hattawy, M. and Hicks, K. and Holtrop, M. and Hyde, C. E. and Ireland, D. G. and Ishkhanov, B. S. and Isupov, E. L. and Jenkins, D. and Joo, K. and Kabir, M. L. and Keller, D. and Khachatryan, G. and Khachatryan, M. and Khandaker, M. and Kim, A. and Kim, W. and Klein, A. and Klein, F. and Kubarovsky, V. and Kuhn, S. E. and Laget, J. M. and Lanza, L. and Lenisa, P. and Lersch, D. and Livingston, K. and MacGregor, I. J. D. and Markov, N. and Mbianda Njencheu, G. and McKinnon, B. and Mineeva, T. and Mokeev, V. and Montgomery, R. A. and Movsisyan, A. and Munoz Camacho, C. and Nadel-Turonski, P. and Niccolai, S. and Niculescu, G. and Osipenko, M. and Ostrovidov, A. I. and Paolone, M. and Park, K. and Pasyuk, E. and Payette, D. and Phelps, W. and Pogorelko, O. and Poudel, J. and Price, J. W. and Procureur, S. and Prok, Y. and Protopopescu, D. and Ripani, M. and Ritchie, B. G. and Rizzo, A. and Rosner, G. and Roy, A. and Sabatié, F. and Salgado, C. and Schadmand, S. and Schumacher, R. A. and Sharabian, Y. G. and Skorodumina, Iu. and Stepanyan, S. and Ireland, D. G. and Sokhan, D. and Sober, D. I. and Sparveris, N. and Strauch, S. and Taiuti, M. and Tan, J. A. and Ungaro, M. and Voskanyan, H. and Voutier, E. and Watts, D. P. and Weinstein, L. and Wei, X. and Weygand, D. P. and Zachariou, N. and Zhang, J. and Zhao, Z. W.},
abstractNote = {Exclusive photoproduction cross sections have been measured for the process $\gamma p \rightarrow p\pi^0(e^+e^-(\gamma))$ with the Dalitz decay final state using tagged photon energies in the range of $E_{\gamma} = 1.275-5.425$ GeV. The complete angular distribution of the final state $\pi^0$, for the entire photon energy range up to large values of $t$ and $u$, has been measured for the first time. The data obtained show that the cross section $d\sigma/dt$, at mid to large angles, decreases with energy as $s^{-6.89\pm 0.26} $. This is in agreement with the perturbative QCD quark counting rule prediction of $s^{-7} $. Paradoxically, the size of angular distribution of measured cross sections is greatly underestimated by the QCD based Generalized Parton Distribution mechanism at highest available invariant energy $s=11$ GeV$^2$. At the same time, the Regge-exchange-based models for $\pi^0$ photoproduction are more consistent with experimental data.},
doi = {10.1103/PhysRevC.98.015207},
journal = {Physical Review C},
number = 1,
volume = 98,
place = {United States},
year = {2018},
month = {7}
}