Far-from-equilibrium heavy quark energy loss at strong coupling

Abstract

We study the energy loss of a heavy quark propagating through the matter produced in the collision of two sheets of energy [P. M. Chesler and L. G. Yaffe, Phys. Rev. Lett. 106, 021601 (2011) [arXiv:1011.3562 [hep-th]].]. Even though this matter is initially far-from-equilibrium we find that, when written in terms of the energy density, the equilibrium expression for heavy quark energy loss describes most qualitative features of our results well. At later times, once a plasma described by viscous hydrodynamics has formed, the equilibrium expression describes the heavy quark energy loss quantitatively. In addition to the drag force that makes it lose energy, a quark moving through the out-of-equilibrium matter feels a force perpendicular to its velocity.