1. Measurement of theΣbeam asymmetry for theωphotoproduction off the proton and the neutron at the GRAAL experiment
- Author
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J. P. Didelez, N. V. Rudnev, A. Fantini, G.V. Russo, Marina Manganaro, V. Vegna, P. Levi Sandri, C. Schaerf, F. Mammoliti, Francesca Curciarello, V. De Leo, R. Di Salvo, V. G. Nedorezov, Giuseppe Mandaglio, M. C. Sutera, F. Ghio, O. Bartalini, A. Turinge, C. Randieri, D. Franco, A. Giusa, Annick Lleres, A. N. Mushkarenkov, A. D'Angelo, D. Rebreyend, Marco Capogni, A. M. Lapik, G. Gervino, M. L. Sperduto, D. Moricciani, L. Casano, J.P. Boquet, B. Girolami, V. Bellini, I. Zonta, M. Castoldi, and G. Giardina
- Subjects
Physics ,Nuclear and High Energy Physics ,Particle physics ,Proton ,010308 nuclear & particles physics ,media_common.quotation_subject ,Nuclear Theory ,Photon energy ,01 natural sciences ,7. Clean energy ,Asymmetry ,Pseudoscalar meson ,Nuclear physics ,Deuterium ,0103 physical sciences ,Physics::Accelerator Physics ,High Energy Physics::Experiment ,Neutron ,Nuclear Experiment ,010306 general physics ,Nucleon ,Beam (structure) ,media_common - Abstract
We report on new measurements of the beam asymmetry for. photoproduction on protons and neutrons in hydrogen and deuterium targets from the GRAAL Collaboration. The beam asymmetry values are extracted from the reaction threshold (E-gamma = 1.1 GeV in the free nucleon kinematics) up to 1.5 GeV of incoming photon energy. For the first time both the radiative and the three-pion decay channels are simultaneously investigated on the free proton. Results from the two decay channels are in agreement, leading to the world's most precise measurements of the beam asymmetry for omega photoproduction off free protons. First experimental results on the deuteron allow the extraction of the Sigma beam asymmetry on quasifree nucleons. The beam asymmetry angular distributions obtained for the free and the quasifree kinematics show the same behavior, similar to the findings in pseudoscalar meson photoproduction reactions. First results of the beam asymmetry on the quasifree neutrons are presented, showing different strengths and angular distributions from the results on the proton target.
- Published
- 2015
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