Formation Time of QGP from Thermal Photon Elliptic Flow

Abstract

We show that the transverse momentum dependent elliptic flow ν 2 ( p T ) of thermal photons is quite sensitive to the initial formation time ( τ 0 ) of Quark Gluon Plasma (QGP) for semi-central collision of gold nuclei at RHIC [R. Chatterjee and D. K. Srivastava, Phys. Rev. C 79, 021901(R) (2009)]. 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 ν 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 ν 2 decreases with smaller τ 0 for p T ⩾ 1.5 GeV . On the other hand we find that the elliptic flow parameter for hadrons depends only marginally on the value of τ 0 .