Sensitivity of the Jet Quenching Observables to the Temperature Dependence of the Energy Loss

Abstract

The quenching of minijet (particles with $p_T>> T, \Lambda_{QCD}$) in ultra-relativistic heavy-ion collisions has been one of the main prediction and discovery at RHIC. We analyze the correlation between different observables like the nuclear modification factor $\Rapt$, the elliptic flow and the ratio of quark to gluon suppressions. We show that the temperature (or entropy density) dependence of the in-medium energy loss strongly affects the relation among these observables. In particular the large elliptic flow and the nearly equal $\Rapt$ of quarks and gluons can be accounted for only if the energy loss occurs mainly around $T_c$ and the $q\leftrightarrow g$ conversion is significant. The use of an equation of state fitted to lattice QCD calculations, slowing down the cooling as $T \to T_c$, seems to contribute to both the enhancement of $v_2$ and the efficiency of the conversion mechanism.