Dilepton production in nucleus-nucleus collisions at top CERN Super Proton Synchrotron energy of 158A GeV within the parton-hadron-string dynamics transport approach
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Dilepton production in In+In collisions at 158A GeV is studied within the microscopic parton-hadron-string dynamics (PHSD) transport approach that incorporates explicit partonic degrees of freedom and dynamical hadronization as well as the more familiar hadronic dynamics in the final reaction stages. A comparison to the data of the NA60 Collaboration shows that the measured dilepton yield is well described by including the collisional broadening of vector mesons, while simultaneously accounting for the electromagnetic radiation of the strongly coupled quark-gluon plasma (sQGP) via off-shell quark-antiquark annihilation, quark annihilation with additional gluon bremsstrahlung, and the gluon-Compton scattering mechanisms. In particular, the spectra in the intermediate mass range (1 GeV M2.5 GeV) are dominated by quark-antiquark annihilation in the nonperturbative QGP. Also, the observed softening of the transverse mass spectra at intermediate masses (1 GeV M2.5 GeV) is approximately reproduced. Furthermore, for dileptons of low masses (M<0.6 GeV), we find a sizable contribution from the quark annihilation with additional gluon bremsstrahlung, thus providing another possible window for probing the properties of the sQGP. 2011 American Physical Society.
author list (cited authors)
Linnyk, O., Bratkovskaya, E. L., Ozvenchuk, V., Cassing, W., & Ko, C. M.
complete list of authors
Linnyk, O||Bratkovskaya, EL||Ozvenchuk, V||Cassing, W||Ko, CM