A Systematic Study on Direct Photon Production from Central Heavy Ion Collisions

Understand

We investigate the production of direct photons in central Au-Au collisions at the relativistic Heavy-Ion Collider (RHIC) at 200 GeV per nucleon, considering all possible sources.

• We treat thermal photons emitted from a quark-gluon plasma and from a hadron gas, based on a realistic thermodynamic expansion.
• Hard photons from elementary nucleon-nucleon scatterings are included: primordial elementary scatterings are certainly dominant at large transverse momenta, but also secondary photons from jet fragmentation and jet-photon conversion cannot be ignored.
• In both cases we study the effect of energy loss, and we also consider photons emitted from bremsstrahlung gluons via fragmentation.