Publications Repository - Helmholtz-Zentrum Dresden-Rossendorf

Study of hadron properties in cold nuclear matter with HADES

Tlusty, P.; Agakishiev, G.; Belver, D.; Belyaev, A.; Berger-Chen, J. C.; Blanco, A.; Böhmer, M.; Cabanelas, P.; Dybczak, A.; Epple, E.; Fabbietti, L.; Fonte, P.; Friese, J.; Fröhlich, I.; Galatyuk, T.; Garzón, J. A.; Golubeva, M.; González-Díaz, D.; Guber, F.; Gumberidze, M.; Hennino, T.; Holzmann, R.; Huck, P.; Ierusalimov, A.; Ivashkin, A.; Jurkovic, M.; Kämpfer, B.; Karavicheva, T.; Koenig, I.; Koenig, W.; Kolb, B. W.; Korcyl, G.; Kornakov, G.; Kotte, R.; Krása, A.; Krizek, F.; Kuc, H.; Kugler, A.; Kurepin, A.; Kurilkin, A.; Kurilkin, P.; Ladygin, V.; Lalik, R.; Lang, S.; Lapidus, K.; Liu, T.; Lopes, L.; Lorenz, M.; Maier, L.; Mangiarotti, A.; Markert, J.; Metag, V.; Michel, J.; Müntz, C.; Münzer, R.; Naumann, L.; Palka, M.; Parpottas, Y.; Pechenov, V.; Pechenova, O.; Pietraszko, J.; Przygoda, W.; Ramstein, B.; Reshetin, A.; Rustamov, A.; Sadovsky, A.; Salabura, P.; Siebenson, J.; Sobolev, Y. G.; Spataro, S.; Ströbele, H.; Stroth, J.; Sturm, C.; Tarantola, A.; Teilab, K.; Traxler, M.; Tsertos, H.; Vasiliev, T.; Wagner, V.; Weber, M.; Wüstenfeld, J.; Yurevich, S.; Zanevsky, Y.

Results of a study of dielectron and pion production in p + Nb collisions at incident proton beam energy 3.5 GeV are presented. The data are taken by the High Acceptance Di-Electron Spectrometer (HADES) at GSI Darmstadt.
The dielectron invariant mass distributions are compared to data from elementary p+p reactions at the same beam energy. At this energy above the light vector meson production threshold, the omega peak is clearly identified. The collected statistics and high acceptance for pair momenta within the interval 50-2000 MeV/c allow for a study of momentum dependence of the omega yield and spectral shape. The strongest medium modification in the line shape is expected for low momenta mesons decaying inside the nuclear matter. Comparing the measured p+Nb data with the p+p reference experiment results, the signifficant change in yield of low momenta dielectron pairs in the vector meson mass region is observed.
Data on charged pi meson emission, which are related to neutral pions representing a dominant contribution to the dielectron yield, are shown as well. They contribute to the results from systematic studies of the pion production in the proton-nucleus collisions, which point to a transition of the pion source from simple NN collisions to emission of thermalized pions from a fireball, when increasing the atomic number of the target nucleus. The data also serve as a reliable tool for normalization of the dielectron data.

  • Open Access Logo Proceedings of Science (2012), Pos(Bormio2012)019

Publ.-Id: 16990