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arXiv · 0804.3805

A systematic study of direct photon production in heavy ion collisions

Ivan Vitev·Ben-Wei Zhang
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Abstract

A theoretical derivation of photon bremsstrahlung, induced by the interactions of an energetic quark in a hot and dense quark-gluon plasma, is given in the framework of the reaction operator approach. For the physically relevant case of hard jet production, followed by few in-medium interactions, we find that the Landau-Pomeranchuk-Migdal suppression of the bremsstrahlung photon intensity is much stronger than in the previously discussed limit of on-shell quarks and a large number of soft scatterings. We present the first systematic study of direct photon production in minimum bias d+Cu and d+Au and central Cu+Cu and Au+Au heavy ion collisions at the Relativistic Heavy Ion Collider at center of mass energies of 62.4 GeV and 200 GeV. We find that the contribution of the final-state photon production at pT < 5 GeV is limited to 35%, and at high transverse momenta, the modification of the direct photon cross section is dominated by initial-state cold nuclear matter effects.

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Ivan Vitev, Ben-Wei Zhang. 2008-11-10. A systematic study of direct photon production in heavy ion collisions. https://doi.org/10.1016/j.physletb.2008.10.019

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