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

CLAS Collaboration

Research output: Contribution to journalArticle

2 Citations (Scopus)

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

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photoproduction
cross sections
angular distribution
quantum chromodynamics
energy
photons
partons
counting
quarks
decay
predictions

ASJC Scopus subject areas

  • Nuclear and High Energy Physics

Cite this

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

In: Physical Review C, Vol. 98, No. 1, 015207, 25.07.2018.

Research output: Contribution to journalArticle

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title = "Exclusive photoproduction of π0 up to large values of Mandelstam variables s, t, and u with CLAS",
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.",
author = "{CLAS Collaboration} and Kunkel, {M. C.} and Amaryan, {M. J.} and Strakovsky, {I. I.} and J. Ritman and Goldstein, {G. R.} and Adhikari, {K. P.} and S. Adhikari and H. Avakian and J. Ball and I. Balossino and L. Barion and M. Battaglieri and V. Batourine and I. Bedlinskiy and Biselli, {A. S.} and S. Boiarinov and Briscoe, {W. J.} and Brooks, {W. K.} and S. B{\"u}ltmann and Burkert, {V. D.} and F. Cao and Carman, {D. S.} and A. Celentano and G. Charles and T. Chetry and G. Ciullo and L. Clark and Cole, {P. L.} and M. Contalbrigo and O. Cortes and V. Crede and A. D'Angelo and N. Dashyan and {De Vita}, R. and {De Sanctis}, E. and Degtyarenko, {P. V.} and M. Defurne and A. Deur and C. Djalali and Michael Dugger and R. Dupre and H. Egiyan and {El Alaoui}, A. and {El Fassi}, L. and L. Elouadrhiri and P. Eugenio and G. Fedotov and R. Fersch and A. Filippi and Barry Ritchie",
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T1 - Exclusive photoproduction of π0 up to large values of Mandelstam variables s, t, and u with CLAS

AU - CLAS Collaboration

AU - Kunkel, M. C.

AU - Amaryan, M. J.

AU - Strakovsky, I. I.

AU - Ritman, J.

AU - Goldstein, G. R.

AU - Adhikari, K. P.

AU - Adhikari, S.

AU - Avakian, H.

AU - Ball, J.

AU - Balossino, I.

AU - Barion, L.

AU - Battaglieri, M.

AU - Batourine, V.

AU - Bedlinskiy, I.

AU - Biselli, A. S.

AU - Boiarinov, S.

AU - Briscoe, W. J.

AU - Brooks, W. K.

AU - Bültmann, S.

AU - Burkert, V. D.

AU - Cao, F.

AU - Carman, D. S.

AU - Celentano, A.

AU - Charles, G.

AU - Chetry, T.

AU - Ciullo, G.

AU - Clark, L.

AU - Cole, P. L.

AU - Contalbrigo, M.

AU - Cortes, O.

AU - Crede, V.

AU - D'Angelo, A.

AU - Dashyan, N.

AU - De Vita, R.

AU - De Sanctis, E.

AU - Degtyarenko, P. V.

AU - Defurne, M.

AU - Deur, A.

AU - Djalali, C.

AU - Dugger, Michael

AU - Dupre, R.

AU - Egiyan, H.

AU - El Alaoui, A.

AU - El Fassi, L.

AU - Elouadrhiri, L.

AU - Eugenio, P.

AU - Fedotov, G.

AU - Fersch, R.

AU - Filippi, A.

AU - Ritchie, Barry

PY - 2018/7/25

Y1 - 2018/7/25

N2 - 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.

AB - 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.

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U2 - 10.1103/PhysRevC.98.015207

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