Exclusive Photoproduction of πº Up to Large Values of Mandelstam Variables s, t, and u with CLAS

Authors

CLAS Collaboration
M. C. Kunkel, Old Dominion University
M. J. Amaryan, Old Dominion UniversityFollow
S. Bültmann, Old Dominion UniversityFollow
G. Charles, Old Dominion University
C. E. Hyde, Old Dominion UniversityFollow
A. Klein, Old Dominion UniversityFollow
S E. KuhnFollow
J. Poudel, Old Dominion University
Y. Prok, Old Dominion UniversityFollow
L. B. Weinstein, Old Dominion UniversityFollow
Z. W. Zhao, Old Dominion University

Document Type

Article

Publication Date

2018

DOI

10.1103/PhysRevC.98.015207

Publication Title

Physical Review C

Volume

98

Issue

1

Pages

015207 (8 pages)

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 E_γ= 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.

Comments

Published by the American Physical Society under the terms of the Creative Commons Attribution 4.0 International license. Further distribution of this work must maintain attribution to the author(s) and the published article's title, journal citation, and DOI. Funded by SCOAP³.

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

ORCID

0000-0001-7282-8120 (Hyde), 0000-0003-2243-6836 (Kuhn), 0000-0001-5416-2900 (Weinstein)

Repository Citation

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.
https://digitalcommons.odu.edu/physics_fac_pubs/231