Bochum 2009 – wissenschaftliches Programm
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HK: Fachverband Hadronen und Kerne
HK 33: Heavy Ion Collisions and QCD phases
HK 33.4: Vortrag
Dienstag, 17. März 2009, 17:45–18:00, H-ZO 10
Finite lifetime effects on the photon emission from a quark gluon plasma — •Frank Michler1, Björn Schenke1,2, and Carsten Greiner1 — 1Institut für theoretische Physik, Johann Wolfgang Goethe Universität Frankfurt am Main, Max von Laue Straße 1, 60438 Frankfurt am Main, Germany — 2Department of Physics, McGill University, H3A 2T8, Montreal, Quebec, Canada
Photons play an important role as electromagnetic probes from a quark gluon plasma created in heavy ion collisions. After being once produced, the leave the medium undisturbed an thus provide direct insight into the early stage of the collision. Here the question arises how non equilibrium effects such as a finite creation time influences the resulting photon spectra. One main result has been the occurrence of first order contributions that dominate over higher order equilibrium contributions for large photon momenta.
Describing this phenomenon in the real time Keldysh formalism is mainly accompanied by two problems, namely the correct treatment of the virtual photon cloud in the vacuum and to get the resulting photon spectra convergent in the ultraviolet domain. We provide an ansatz allowing for the unambiguous identification and thus renormalization of the virtual photon cloud of the vacuum. Furthermore, it renders the spectrum of emitted photons UV-finite if the time evolution of the medium is simulated in a suitable manner.