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Dileptons and Photons from Coarse-Grained Microscopic Dynamics and Hydrodynamics Compared to Experimental Data

P. Huovinen·M. Belkacem·P. J. Ellis·J. I. Kapusta
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Abstract

Radiation of dileptons and photons from high energy nuclear collisions provides information on the space-time evolution of the hot dense matter produced therein. We compute this radiation using relativistic hydrodynamics and a coarse-grained version of the microscopic event generator UrQMD, both of which provide a good description of the hadron spectra. The currently most accurate dilepton and photon emission rates from perturbative QCD and from experimentally-based hadronic calculations are used. Comparisons are made to data on central Pb-Pb and Pb-Au collisions taken at the CERN SPS at a beam energy of 158 A GeV. Both hydrodynamics and UrQMD provide very good descriptions of the photon transverse momentum spectrum measured between 1 and 4 GeV, but slightly underestimate the low mass spectrum of e+e- pairs, even with greatly broadened rho and omega vector mesons. Predictions are given for the transverse momentum distribution of dileptons.

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P. Huovinen, M. Belkacem, P. J. Ellis, J. I. Kapusta. 2002-03-11. Dileptons and Photons from Coarse-Grained Microscopic Dynamics and Hydrodynamics Compared to Experimental Data. https://doi.org/10.1103/physrevc.66.014903

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