Eur. Phys. J. C (2011) 71: 1615
https://doi.org/10.1140/epjc/s10052-011-1615-4

Regular Article - Theoretical Physics

Dilepton production in p+p, Cu+Cu and Au+Au collisions at GeV

¹ Institut für Theoretische Physik, Universität Giessen, 35392, Giessen, Germany
² Institut für Theoretische Physik, Universität Frankfurt, 60054, Frankfurt, Germany

^* e-mail: Mannisenjaakko@gmail.com

Received: 1 July 2010
Revised: 7 December 2010
Published online: 8 April 2011

Abstract

We study dilepton production in proton–proton, Cu+Cu as well as in Au+Au collisions at the center-of-mass energy  GeV per participating nucleon pair within an extended statistical hadronization model. In extension to earlier studies we incorporate transport calculations for an estimate of uncorrelated e ⁺ e ⁻ -pairs from semileptonic D meson decays. While the invariant mass spectrum of dielectrons is well understood in the p+p collisions, severe discrepancies among different model scenarios based on hadronic degrees of freedom and recent data from the PHENIX Collaboration are found in heavy-ion collisions in the low-mass region from 0.15 to 0.6 GeV as well as in the intermediate mass regime from 1.1 to 3 GeV when employing the standard dilepton sources. We investigate, furthermore, the background from correlated dileptons that are not emitted as a pair from a parent hadron but emerge from semileptonic decays of two correlated daughter hadrons. Our calculations suggest a sizeable contribution of such sources in central heavy-ion collisions in the low-mass region. However, even the upper limits of our calculations are found to be far below the dilepton mass spectra of the PHENIX Collaboration.