This title appears in the Scientific Report :
2018
Please use the identifier:
http://dx.doi.org/10.1103/PhysRevC.98.015207 in citations.
Please use the identifier: http://hdl.handle.net/2128/19462 in citations.
Exclusive photoproduction of π 0 up to large values of Mandelstam variables s , t , and u with CLAS
Exclusive photoproduction of π 0 up to large values of Mandelstam variables s , t , and u with CLAS
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 value...
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Please use the identifier: http://hdl.handle.net/2128/19462 in citations.
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. |