Darmstadt 2016 – scientific programme
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HK: Fachverband Physik der Hadronen und Kerne
HK 10: Heavy Ion Collision and QCD Phases III
HK 10.4: Talk
Monday, March 14, 2016, 17:30–17:45, S1/01 A01
Polarization of exclusive dilepton production in pion-nucleon collisions — •Enrico Speranza1,2, Miklós Zétényi3, and Bengt Friman1 — 1GSI Helmholtzzentrum für Schwerionenforschung, Darmstadt — 2Technische Universität Darmstadt — 3Wigner Research Centre for Physics, Budapest, Hungary
A study of the polarization of the virtual photon in the process π N → Ne+ e− is presented [1]. Effective interactions describing only the physical degrees of freedom for baryon resonances up to spin-5/2 are employed to compute the spin-anisotropy coefficient for isolated intermediate baryon resonances. It is shown that a given spin state of the intermediate resonance exhibits a characteristic angular dependence of the spin-anisotropy coefficient. Furthermore, the anisotropy coefficient resulting from the interference between resonances with different spin is presented. Our results show that the polarization of the photon provides information that is useful for disentangling the resonance contributions to elementary dilepton production processes [2]. Moreover, it is argued that the study of polarization observables can provide information on the production process and equilibration mechanism in heavy-ion collisions.
E. Speranza, M. Zétényi, and B. Friman (to be published)
W. Przygoda (HADES Collaboration), talk presented at The 10th International Workshop on the Physics of Excited Nucleons, NSTAR2015, 25-28 May 2015, Osaka