First measurement of proton-induced low-momentum dielectron radiation off cold nuclear matter

Publication Type
Journal Article
Year of Publication
Agakishiev, G.
Balanda, A.
Belver, D.
Belyaev, A.
Berger-Chen, J. C.
Blanco, A.
Bohmer, M.
Boyard, J. L.
Cabanelas, P.
Chernenko, S.
Dybczak, A.
Epple, E.
Fabbietti, L.
Fateev, O.
Finocchiaro, P.
Fonte, P.
Friese, J.
Frohlich, I.
Galatyuk, T.
Garzon, J. A.
Gernhauser, R.
Gobelg, K.
Golubeva, M.
Gonzalez-Diaz, D.
Guber, F.
Gumberidze, M.
Heinz, T.
Hennino, T.
Holzmann, R.
Ierusalimov, A.
Iori, I.
Jurkovic, M.
Kampfer, B.
Karavicheva, T.
Koenig, I.
Koenig, W.
Kolb, B. W.
Kornakov, G.
Kotte, R.
Krasa, A.
Krizek, F.
Krucken, R.
Kuc, H.
Kuhn, 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.
Muntz, C.
Naumann, L.
Pachmayer, Y. C.
Palka, M.
Parpottas, Y.
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. G.
Spataro, S.
Spruck, B.
Strobele, H.
Stroth, J.
Sturm, C.
Tarantola, A.
Teilab, K.
Tlusty, P.
Traxler, M.
Trebacz, R.
Tsertos, H.
Vasiliev, T.
Wagner, V.
Weber, M.
Wendisch, C.
Wustenfeld, J.
Yurevich, S.
Zanevsky, Y.
Collaboration, Hades
Name of Publication
Physics Letters B
Date Published
Short Title
First measurement of proton-induced low-momentum dielectron radiation off cold nuclear matter
Accession Number
ISBN Number

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 rho-like contribution and a decrease of omega yield. These opposite trends are tentatively interpreted as a strong coupling of the rho meson to baryonic resonances and an absorption of the omega meson, which are two aspects of in-medium modification of vector mesons. (c) 2012 Elsevier B.V. All rights reserved.