Measuring the isotropization time of quark-gluon plasma from direct photons at energies available at the BNL Relativistic Heavy Ion Collider (RHIC)

Abstract

We calculate transverse momentum distribution of direct photons from various sources by taking into account the initial state momentum anisotropy of {\em Quark-Gluon-Plasma} (QGP) and late stage transverse flow effects. The total photon yield, calculated for various combinations of initial conditions, transition temperatures, is then compared with the recent measurement of photon transverse momentum distribution by the PHENIX collaboration. It is shown that the presence of such an anisotropy can describe the PHENIX photon data better than the isotropic case. We show that the isotropization time thus extracted remains of the order of 1 fm/c and is almost insensitive to the initial conditions used.

12 pages, 11 eps figures

References in corpus (6)

• The transition temperature in QCD
• Measurement of direct photon production in p + p collisions at sqrt(s) = 200 GeV
• Pre-equilibrium dilepton production from an anisotropic quark-gluon plasma
• Electromagnetic radiation from nuclear collisions at RHIC energies
• Photon production from an anisotropic quark-gluon plasma
• Evolution of Anisotropy of Parton System from Relativistic Heavy-Ion Collisions