Photons: as a probe of anisotropic Quark-Gluon-Plasma

by lusaka bhattacharya (Saha Institute of Nuclear physics)

Monday 1 Nov 2010, 14:00 → 15:00 Europe/Zurich

160/1-009 (CERN)

We calculate medium photons due to Compton and annihilation processes in an anisotropic media. The effects of time-dependent momentum-space anisotropy of Quark-Gluon-Plasma (QGP) on the medium photon production are discussed. Such an anisotropy can results from the initial rapid longitudinal expansion of the matter, created in relativistic heavy ion collisions. A phenomenological model for the time-dependence of the parton hard momentum scale, $p_{hard}(\tau)$, and anisotropy parameter, $\xi(\tau)$, has been used to describe the plasma space-time evolution. We find significant dependency of photon yield on the isotropization time ($\tau_{iso}$). It is shown that the introduction of early time momentum-space anisotropy can enhance the photon production by a factor of $10~(1.5)$ (in the central rapidity region) for free streaming (collisionally-broadened) interpolating model if we assume fixed initial condition. On the other hand, enforcing the fixed final multiplicity significantly reduces the enhancement of medium photon production.