Authors

M. C. Kunkel, Old Dominion University
M. J. Amaryan, Old Dominion University
I. I. Strakovsky, The George Washington University
J. Ritman, Ruhr-Universität Bochum, Germany
G. R. Goldstein, Tufts University
K. P. Adhikari, Mississippi State University
S. Adhikari, Florida International University
H. Avakian, Thomas Jefferson National Accelerator Facility
J. Ball, Universit’e Paris-Saclay, France
I. Balossino, Istituto Nazionale di Fisica Nucleare, Italy
L. Barion, Istituto Nazionale di Fisica Nucleare, Italy
M. Battaglieri, Istituto Nazionale di Fisica Nucleare, Italy
V. Batourine, Thomas Jefferson National Accelerator Facility
I. Bedlinskiy, Institute of Theoretical and Experimental Physics, Russia
A. S. Biselli, Fairfield University
S. Boiarinov, Thomas Jefferson National Accelerator Facility
W. J. Briscoe, The George Washington University
W. K. Brooks, Universidad Técnica Federico Santa María, Chile
S. Bültmann, Old Dominion University
V. D. Burkert, Thomas Jefferson National Accelerator Facility
F. Cao, University of Connecticut
D. S. Carman, Thomas Jefferson National Accelerator Facility
A. Celentano, Istituto Nazionale di Fisica Nucleare, Italy
G. Charles, Old Dominion University
T. Chetry, Ohio University
G. Ciullo, Istituto Nazionale di Fisica Nucleare, Italy
L. Clark, University of Glasgow, UK
P. L. Cole, Idaho State University
M. Contalbrigo, Istituto Nazionale di Fisica Nucleare, Italy
O. Cortes, Idaho State University
Wesley P. Gohn, University of KentuckyFollow

Abstract

Exclusive photoproduction cross sections have been measured for the process γp 0[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 /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 = 11 GeV2. At the same time, the Regge-exchange-based models for π0 photoproduction are more consistent with experimental data.

Document Type

Article

Publication Date

7-25-2018

Notes/Citation Information

Published in Physical Review C, v. 98, issue 1, 015207, p. 1-8.

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.

Due to the large number of authors, only the first 30 and the authors affiliated with the University of Kentucky are listed in the author section above. For the complete list of authors, please download this article or visit: https://doi.org/10.1103/PhysRevC.98.015207

This group of authors is collectively known as The CLAS Collaboration.

Digital Object Identifier (DOI)

https://doi.org/10.1103/PhysRevC.98.015207

Funding Information

Funded by SCOAP3.

This work was supported in part by the Italian Istituto Nazionale di Fisica Nucleare, the French Centre National de la Recherche Scientifique and Commissariat à l’Energie Atomique, the United Kingdom’s Science and Technology Facilities Council (STFC), the US DOE and NSF, and the National Research Foundation of Korea. This material is based upon work supported by the U.S. Department of Energy, Office of Science, Office of Nuclear Physics, under Contract No. DE-AC05-06OR23177.

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