Dielectron production in pp and dp collisions at 1.25 GeV/u with HADES

Lapidus, K.; Agakishiev, G.; Agodi, C.; Balanda, A.; Bellia, G.; Belver, D.; Belyaev, A. V.; Blanco, A.; Boehmer, M.; Boyard, J. L.; Braun Munzinger, P.; Cabanelas, P.; Castro, E.; Chernenko, S.; Christ, T.; Destefanis, MARCO GIOVANNI; Dìaz, J.; Dohrmann, F.; Dybczak, A.; Eberl, T.; Fabbietti, L.; Fateev, O. V.; Finocchiaro, P.; Fonte, P.; Friese, J.; Froehlich, I.; Galatyuk, T.; Garzòn, J. A.; Gernhaeuser, R.; Gil, A.; Gilardi, C.; Golubeva, M.; Gonzàlez Dìaz, D.; Grosse, E.; Guber, F.; Heilmann, M.; Hennino, T.; Holzmann, R.; Ierusalimov, A. P.; Iori, I.; Ivashkin, A.; Jurkovic, M.; Kaempfer, B.; Kanaki, K.; Karavicheva, T.; Kirschner, D.; Koenig, I.; Koenig, W.; Kolb, B. W.; Kotte, R.; Kozuch, A.; Kràsa, A.; Krizek, F.; Kruecken, R.; Kuehn, W.; Kugler, A.; Kurepin, A.; Lamas Valverde, J.; Lang, S.; Lange, J. S.; Lopes, L.; Lorenz, M.; Maier, L.; Mangiarotti, A.; Marìn, J.; Markert, J.; Metag, V.; Michalska, B.; Michel, J.; Mishra, D.; Morinière, E.; Mousa, J.; Muentz, C.; Naumann, L.; Novotny, R.; Otwinowski, J.; Pachmayer, Y. C.; Palka, M.; Parpottas, Y.; Pechenov, V.; Pechenova, O.; Pérez Cavalcanti, T.; Pietraszko, J.; Przygoda, W.; Ramstein, B.; Reshetin, A.; Rustamov, A.; Sadovsky, A.; Salabura, P.; Schmah, A.; Simon, R.; Sobolev, Y. u. G.; Spataro, STEFANO GIOVANNI; Spruck, B.; Stroebele, H.; Stroth, J.; Sturm, C.; Sudol, M.; Tarantola, A.; Teilab, K.; Tlusty, P.; Traxler, M.; Trebacz, R.; Tsertos, H.; Veretenkin, I.; Wagner, V.; Weber, M.; Wisniowski, M.; Wuestenfeld, J.; Yurevich, S.; Zanevsky, Y. V.; Zhou, P.; Zumbruch, P.

Inclusive production of e+e−-pairs in pp and dp collisions at a kinetic beam energy of 1.25 GeV/u has been studied with the HADES spectrometer. In the latter case, the main goal was to obtain data on pair emission in quasi-free np collisions. To select this particular reaction channel the HADES experimental setup was extended with a Forward Wall hodoscope, which allowed to register spectator protons. Here, the measured invariant mass distributions demonstrate a strong enhancement of the pair yield for M > 140 MeV/c2 in comparison to pp data.