paper

Formation Time of QGP from Thermal Photon Elliptic Flow

arXiv:0907.3548 · doi:10.1016/j.nuclphysa.2009.10.043

Abstract

We show that the transverse momentum dependent elliptic flow $v_{2} (p_{T})$ of thermal photons is quite sensitive to the initial formation time ( $I ¨ _{0}$ ) of Quark Gluon Plasma (QGP) for semi-central collision of gold nuclei at RHIC \cite{tau}. A smaller value of the formation time or a larger initial temperature leads to a significant increase in the thermal photon radiation from QGP phase, which has a smaller $v_{2}$ . The elliptic flow of thermal photon is dominated by the contribution from the quark matter at intermediate and high $p_{T}$ range and as a result sum $v_{2}$ decreases with smaller $I ¨ _{0}$ for $p_{T} \geq 1.5$ GeV. On the other hand we find that the elliptic flow parameter for hadrons depends only marginally on the value of $I ¨ _{0}$ .

4 pages, 3 figures - To appear in the conference proceedings for Quark Matter 2009, March 30 - April 4, Knoxville, Tennessee, v2: minor corrections