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

CLAS Collaboration

Research output: Contribution to journalArticle

4 Scopus citations

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.

Original languageEnglish (US)
Article number015207
JournalPhysical Review C
Volume98
Issue number1
DOIs
StatePublished - Jul 25 2018

ASJC Scopus subject areas

  • Nuclear and High Energy Physics

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