Abstract: Title: Reaction operator approach to medium-induced photon bremsstrahlung:theory and phenomenology
Authors: Ivan Vitev and Ben-Wei Zhang
Abstract: Theoretical derivation of the 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 operation 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 it was argued
to be in the limit of on-quark quarks and large number of soft scatterings. We then
present the first systematic study of direct photon production in minimum bias d+Au and d+Cu and
central Au+Au and Cu+Cu heavy ion collisions at RHIC at center of mass energies and
62.4GeV. We find that the contribution of the final-state photon production at $p_T<5$GeV is limited to
less than 50% and at high transverse momenta the modification of direct photon production is dominated
by initial-state cold nuclear matter effects.