1. Exclusive photoproduction of π 0 up to large values of Mandelstam variables s , t , and u with CLAS
- Author
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Kunkel, Michael C., Amaryan, M. J., Barion, L., Nadel-Turonski, P., Niccolai, S., Niculescu, G., Osipenko, M., Ostrovidov, A. I., Paolone, M., Park, K., Pasyuk, E., Payette, D., Phelps, W., Battaglieri, M., Pogorelko, O., Poudel, J., Price, J. W., Procureur, S., Prok, Y., Protopopescu, D., Ripani, M., Ritchie, B. G., Rizzo, A., Rosner, G., Batourine, V., Roy, A., Sabatié, F., Salgado, C., Schadmand, S., Schumacher, R. A., Sharabian, Y. G., Skorodumina, Iu., Stepanyan, S., Ireland, D. G., Sokhan, D., Bedlinskiy, I., Sober, D. I., Sparveris, N., Strauch, S., Taiuti, M., Tan, J. A., Ungaro, M., Voskanyan, H., Voutier, E., Watts, D. P., Weinstein, L., Biselli, A. S., Wei, X., Weygand, D. P., Zachariou, N., Zhang, J., Zhao, Z. W., Boiarinov, S., Briscoe, W. J., Brooks, W. K., Bültmann, S., Burkert, V. D., Strakovsky, I. I., Cao, F., Carman, D. S., Celentano, A., Charles, G., Chetry, T., Ciullo, G., Clark, L., Cole, P. L., Contalbrigo, M., Cortes, O., Ritman, J., Crede, V., D'Angelo, A., Dashyan, N., De Vita, R., De Sanctis, E., Degtyarenko, P. V., Defurne, M., Deur, A., Djalali, C., Dugger, M., Goldstein, G. R., Dupre, R., Egiyan, H., El Alaoui, A., El Fassi, L., Elouadrhiri, L., Eugenio, P., Fedotov, G., Fersch, R., Filippi, A., Fradi, A., Adhikari, K. P., 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., Adhikari, S., Griffioen, K. A., Guo, L., Guidal, M., Hafidi, K., Hakobyan, H., Harrison, N., Hattawy, M., Hicks, K., Holtrop, M., Hyde, C. E., Avakian, H., Ishkhanov, B. S., Isupov, E. L., Jenkins, D., Joo, K., Kabir, M. L., Keller, D., Khachatryan, G., Khachatryan, M., Khandaker, M., Ball, J., Kim, A., Kim, W., Klein, A., Klein, F., Kubarovsky, V., Kuhn, S. E., Laget, J. M., Lanza, L., Lenisa, P., Lersch, D., Balossino, I., Livingston, K., MacGregor, I. J. D., Markov, N., Mbianda Njencheu, G., McKinnon, B., Mineeva, T., Mokeev, V., Montgomery, R. A., Movsisyan, A., and Munoz Camacho, C.
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High Energy Physics::Experiment ,ddc:530 - Abstract
Exclusive photoproduction cross sections have been measured for the process γp→pπ0[e+e−(γ)] with the Dalitz decay final state using tagged photon energies in the range of Eγ=1.275–5.425 GeV. The complete angular distribution of the final state π0, 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 dσ/dt, 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=11GeV2. At the same time, the Regge-exchange-based models for π0 photoproduction are more consistent with experimental data.
- Published
- 2018
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