First measurement of proton-induced low-momentum dielectron radiation off cold nuclear matter
Date
2012Author
Krücken, R.Agakishiev, G.
Bałanda, A.
Belver, D.
Belyaev, A.
Berger-Chen, J. C.
Blanco, A.
Böhmer, M.
Boyard, J. L.
Cabanelas, Pablo
Chernenko, S.
Dybczak, A.
Epple, E.
Fabbietti, L.
Fateev, O.
Finocchiaro, P.
Fonte, P.
Friese, J.
Fröhlich, I.
Galatyuk, T.
Garzón, J. A.
Gernhäuser, R.
Göbel, K.
Golubeva, M.
González-Díaz, D.
Guber, F.
Gumberidze, M.
Heinz, T.
Hennino, T.
Holzmann, R.
Ierusalimov, A.
Iori, I.
Ivashkin, A.
Jurkovic, M.
Kämpfer, B.
Karavicheva, T.
Koenig, I.
Koenig, W.
Kolb, B. W.
Kornakov, G.
Kotte, R.
Krása, Antonín
Krizek, F.
Kuc, H.
Kühn, W.
Kugler, A.
Kurepin, A.
Ladygin, V.
Lalik, R.
Lang, S.
Lapidus, K.
Lebedev, A.
Liu, T.
Lopes, L.
Lorenz, M.
Maier, L.
Mangiarotti, A.
Markert, J.
Metag, V.
Michalska, B.
Michel, J.
Mishra, D.
Müntz, C.
Naumann, L.
Pachmayer, Y. C.
Palka, M.
Parpottas, Yiannis
Pechenov, V.
Pechenova, O.
Pietraszko, J.
Przygoda, W.
Ramstein, B.
Reshetin, A.
Rustamov, A.
Sadovsky, A.
Salabura, P.
Schmah, A.
Schwab, E.
Siebenson, J.
Sobolev, Y.
Spataro, S.
Spruck, B.
Ströbele, H.
Stroth, J.
Sturm, C.
Tarantola, A.
Teilab, K.
Tlusty, P.
Traxler, M.
Trebacz, R.
Tsertos, Haralambos
Vasiliev, T.
Wagner, V.
Weber, M.
Wendisch, C.
Wüstenfeld, J.
Yurevich, S.
Zanevsky, Y.
Source
Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy PhysicsVolume
715Issue
4-5Pages
304-309Google Scholar check
Metadata
Show full item recordAbstract
We present data on dielectron emission in proton induced reactions on a Nb target at 3.5 GeV kinetic beam energy measured with HADES installed at GSI. The data represent the first high statistics measurement of proton-induced dielectron radiation from cold nuclear matter in a kinematic regime, where strong medium effects are expected. Combined with the good mass resolution of 2%, it is the first measurement sensitive to changes of the spectral functions of vector mesons, as predicted by models for hadrons at rest or small relative momenta. Comparing the e +e - invariant mass spectra to elementary p+p data, we observe for e +e - momenta P ee<0.8 GeV/c a strong modification of the shape of the spectrum, which we attribute to an additional ρ-like contribution and a decrease of ω yield. These opposite trends are tentatively interpreted as a strong coupling of the ρ meson to baryonic resonances and an absorption of the ω meson, which are two aspects of in-medium modification of vector mesons. © 2012 Elsevier B.V.