(English) Measurement of the Σ beam asymmetry for the ω photo-production off the proton and the neutron at the GRAAL experiment

We report on new measurements of the beam asymmetry for ω photo-production on proton and neutron in Hydrogen and Deuterium targets from the GRAAL collaboration. The beam asymmetry values are extracted from the reaction threshold (E = 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 and provide important constraints for the determination of resonant state contributions to the ω production mechanism. First experimental results on the deuteron allow the extraction of the _ beam asymmetry on quasi-free nucleons. Comparison of the results for free and quasi-free kinematics on the proton shows a generally reasonable agreement, similar to the findings in pseudo-scalar meson photo-production reactions. For the first time measurements on quasi-free neutrons are available, showing that both the strength and the angular distributions of the beam asymmetry are sensibly different from the results on the proton target.


V. Vegna, A. D’Angelo, O. Bartalini, V. Bellini, J. P. Boquet, M. Capogni, L. E. Casano, M. Castoldi, F. Curciarello, V. De Leo, J. P. Didelez, R. Di Salvo, A. Fantini, D. Franco, G. Gervino, F. Ghio, G. Giardina, B. Girolami, A. Giusa, A. Lapik, P. Levi Sandri, A. Lleres, F. Mammoliti, G. Mandaglio, M. Manganaro, D. Moricciani, A. Mushkarenkov, V. Nedorezov, C. Randieri, D. Rebreyend, N. Rudnev, G. Russo, C. Schaerf, M. L. Sperduto, M. C. Sutera, A. Turinge, I. Zonta (2013) 

Physical Review C – June 2015, Vol. 91, Issue 6, pp. 065207-1-065207-13, doi: 10.1103/PhysRevC.91.065207.


Physical Review C (PRC) contains research articles reporting experimental and theoretical results in all aspects of nuclear physics, including the nucleon-nucleon interaction, few-body systems, nuclear structure, nuclear reactions, relativistic nuclear collisions, hadronic physics and QCD, electroweak interaction, symmetries, and nuclear astrophysics.

Cristian Randieri

Cristian Randieri is a brilliant intelligent and great proactivity person and an effective communicator and visionary. He has built a strong (and deserved) reputation as someone with vision, diligence and honour. Cristian is not a simple engineer but he is a real Scientist. His knowledge is not restricted to the area it covers, but its impressive passion for all the technical topics led him to acquire great skills even in areas far from his original studies. Cristian is able to address and solve complex technical problems with excellent results. He is a valuable writer with great scientific background formed with more than 15 years of active research on experimental Nuclear Physics performed in the most famous international research laboratories such as CERN, ESRF, INF. He write about HI-Tech solutions topics and advanced research study applied to industry. With more than 150 scientific & technical publications, he is also, a technical and famous writer in Italy due to his interviews released to the most famous Industrial Italian magazines. Actually, he is the President & CEO of Intellisystem Technologies an Italian Research & Developments company committed to develop and sell innovative and advanced solutions.

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