Bochum 2009 – scientific programme
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HK: Fachverband Hadronen und Kerne
HK 23: Heavy Ion Collisions and QCD phases
HK 23.5: Talk
Tuesday, March 17, 2009, 15:30–15:45, H-ZO 10
Direct Photons in heavy-ion collisions from microscopic transport theory and fluid dynamics — •Bjørn Bäuchle1,2 and Marcus Bleicher2 — 1Frankfurt Institute for Advanced Studies — 2Institut für Theoretische Physik
Direct photons are a unique probe to get information about the early stages of a heavy-ion reaction. Due to the small rescattering cross-section they can leave the medium unperturbed.
The emission of direct photons in heavy-ion collisions is calculated within the relativistic microscopic transport model UrQMD. We compare results from the pure transport calculation to a hybrid-model calculation, where the high-density part of the evolution is replaced by an ideal 3D fluiddynamic calculation. We also compare the thermal rates from infinite matter-calculations to those used in the fluiddynamic part.
Furthermore, we study the contribution of different production channels and non-thermal collisions to the spectrum of direct photons. Detailed comparison to the measurements by experiments at CERN-SPS (WA98) are undertaken.