Photon production in an expanding and chemically equilibrating gluon-enriched plasma

Abstract

Forschungszentrum Rossendorf e.V.case of a weakly first-order confinement transition. OCR Output from deconiined matter dominates for conditions, estimated to be achieved at RHIC, in an equation of state with reduced latent heat. The photon yield in the region E > 1 GeV due to transverse expansion, of photons from hadron matter is shown to be reduced for evolution of matter through mixed and hadron phases. The transverse momentum kick, equilibration, despite of faster cooling. For an assumed fast equilibration we follow the Medium-energy photons with E ~ 1 GeV are more frequently produced in case of faster insensitive to chemical equilibration and depend mainly on the initial thermalized state.ons is followed by rate equations. The yields of hard photons with E 2 2 GeV are initially little quark admixture is considered. Chemical equilibration of quarks and glu Photon production in a longitudinally and transversely expanding gluon plasma with Photon production in an expanding and chemically equilibrating to the standard bag model equation of state) and the transverse momentum kick of the OCR Output latent heat in the confinement transition the transverse expansion is reduced (compared kick which the photons experience from the later hadronic stage. We show that for small for the transverse expansion we discuss in the Appendix also the transverse momentum processes. The summary can be found in section 4. Besides the global hydrodynamics find that the photon yield is not very sensitive to the details of the chemical equilibration gluon phase space saturation achieved depends strongly on the reaction cross sections, we section 3 to analyze the photon yield from the equilibrating plasma. While the quark global hydrodynamical scheme (presented in detail in Appendix). We use the results in scaling hydrodynamics and transverse expansion. The latter one is treated within a new gluon equilibration processes by using rate equations solved together with boost invariant Our paper is organized as follows. In section 2 we consider the chemical quark and refinements probably will allow for an identification of thermal photons.indicate that the photon spectra are dominated by hadronic decays [13]. But experimental The NA34 and WASO photon measurements at previous SPS oxygen and sulphur runs quantified.the relation of thermal photons from deconnned matter to such ones from hadron can be the evolution of equilibrated matter through a mixed phase into hadron matter. Therefore, model, which includes longitudinal and transverse expansion till freeze-out, we can follow chemical equilibration process can affect the photon yields. Since we employ a complete equations [8, 12] The large gluon-gluon cross section helps to thermalize quickly the gluon system. ln a admixed [2,3]. Present parton cascade models support such a picture [4,5, 6, 7, 8].heavy-ion collisions probably a gluon plasma is initially created with only a few quarks quark-quark or quark-gluon scatterings. This fact seems to imply that in ultra-relativistic QCD. Perturbati...

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