Direct photon emission from hadronic sources: hydrodynamics vs. transport theory
Abstract
Direct photon emission in heavy-ion collisions is calculated within the relativistic microscopic transport model UrQMD. We compare the results from the pure transport calculation to a hybrid-model calculation, where the high-density part of the evolution is replaced by an ideal 3-dimensional fluid-dynamic calculation. The effects of viscosity, present in the transport model but neglected in ideal fluid dynamics, are examined. We study the contribution of different production channels and non-thermal collisions to the spectrum of direct photons. Detailed comparisons to the measurements by the WA 98 collaboration are undertaken.
- Publication:
-
European Physical Journal C
- Pub Date:
- July 2009
- DOI:
- 10.1140/epjc/s10052-009-0987-1
- arXiv:
- arXiv:0810.0488
- Bibcode:
- 2009EPJC...62...75B
- Keywords:
-
- Photon Spectrum;
- Direct Photon;
- Transverse Momentum Spectrum;
- Super Proton Synchrotron;
- Fractional Photon;
- Nuclear Theory
- E-Print:
- 6 pages, 4 figures. Contribution to Hot Quarks 2008