Physical Review C
015207 (8 pages)
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.
Original Publication Citation
CLAS Collaboration, Kunkel, M. C., Amaryan, M. J., Strakovsky, I. I., Ritman, J., Goldstein, G. R., . . . Zhao, Z. W. (2018). Exclusive photoproduction of πº 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
0000-0001-7282-8120 (Hyde), 0000-0003-2243-6836 (Kuhn), 0000-0001-5416-2900 (Weinstein)
CLAS Collaboration; Kunkel, M. C.; Amaryan, M. J.; Bültmann, S.; Charles, G.; Hyde, C. E.; Klein, A.; Kuhn, S E.; Poudel, J.; Prok, Y.; Weinstein, L. B.; and Zhao, Z. W., "Exclusive Photoproduction of πº Up to Large Values of Mandelstam Variables s, t, and u with CLAS" (2018). Physics Faculty Publications. 231.