First measurement of proton-induced low-momentum dielectron radiation off cold nuclear matter
Articolo
Data di Pubblicazione:
2012
Abstract:
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.
Tipologia CRIS:
03A-Articolo su Rivista
Keywords:
VECTOR-MESONS; RHO-MESON; COLLISIONS; WIDTH
Elenco autori:
G. Agakishiev;A. Balanda;D. Belver;A. Belyaev;J.C. Berger-Chen;A. Blanco;M. Böhmer;J.L. Boyard;P. Cabanelas;S. Chernenko;A. Dybczak;E. Epple;L. Fabbietti;O. Fateev;P. Finocchiaro;P. Fonte;J. Friese;I. Fröhlich;T. Galatyuk;J.A. Garzón;R. Gernhäuser;K. Göbel;M. Golubeva;D. González-Díaz;F. Guber;M. Gumberidze;T. Heinz;T. Hennino;R. Holzmann;A. Ierusalimov;I. Iori;A. Ivashkin;M. Jurkovic;B. Kämpfer;T. Karavicheva;I. Koenig;W. Koenig;B.W. Kolb;G. Kornakov;R. Kotte;A. Krása;F. Krizek;R. Krücken;H. Kuc;W. Kühn;A. Kugler;A. Kurepin;V. Ladygin;R. Lalik;S. Lang;K. Lapidus;A. Lebedev;T. Liu;L. Lopes;M. Lorenz;L. Maier;A. Mangiarotti;J. Markert;V. Metag;B. Michalska;J. Michel;D. Mishra;C. Müntz;L. Naumann;Y.C. Pachmayer;M. Palka;Y. Parpottas;V. Pechenov;O. Pechenova;J. Pietraszko;W. Przygoda;B. Ramstein;A. Reshetin;A. Rustamov;A. Sadovsky;P. Salabura;A. Schmah;E. Schwab;J. Siebenson;Yu.G. Sobolev;S. Spataro;B. Spruck;H. Ströbele;J. Stroth;C. Sturm;A. Tarantola;K. Teilab;P. Tlusty;M. Traxler;R. Trebacz;H. Tsertos;T. Vasiliev;V. Wagner;M. Weber;C. Wendisch;J. Wüstenfeld;S. Yurevich;Y. Zanevsky
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