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

Kunkel, M. C. et al. (2018) Exclusive photoproduction of π0 up to large values of Mandelstam variables s,t, and u with CLAS. Physical Review C, 98(1), 015207. (doi: 10.1103/PhysRevC.98.015207)

Abstract

Exclusive photoproduction cross sections have been measured for the process γ p → p π 0 [ e + e − ( γ ) ] with the Dalitz decay final state using tagged photon energies in the range of E γ = 1.275 – 5.425 GeV. The complete angular distribution of the final state π 0 , for the entire photon energy range up to large values of t and u , has been measured for the first time. The data obtained show that the cross section d σ / d t , at mid to large angles, decreases with energy as s − 6.89 ± 0.26 . This is in agreement with the perturbative QCD quark counting rule prediction of s − 7 . Paradoxically, the size of angular distribution of measured cross sections is greatly underestimated by the QCD-based generalized parton distribution mechanism at highest available invariant energy s = 11 GeV 2 . At the same time, the Regge-exchange-based models for π 0 photoproduction are more consistent with experimental data.

• Item Type: Articles
• Status: Published
• Refereed: Yes
• Glasgow Author(s) Enlighten ID: Sokhan, Dr Daria and Glazier, Dr Derek and Protopopescu, Dr Dan and MacGregor, Professor Douglas and McKinnon, Dr Bryan and Clark, Ms Louise and Livingston, Dr Kenneth and Montgomery, Dr Rachel and Ireland, Professor David and Rosner, Professor Guenther
• Authors: 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, I., 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.
• College/School: College of Science and Engineering > School of Physics and Astronomy
• Journal Name: Physical Review C
• Publisher: American Physical Society
• ISSN: 2469-9985
• ISSN (Online): 2469-9993
• Published Online: 25 July 2018
• Copyright Holders: Copyright © 2018 American Physical Society
• First Published: First published in Physical Review C 98(1): 015207
• Publisher Policy: Reproduced under a Creative Commons License