1202.2737 (Navid Abbasi et al.)

Moving Quark in a Viscous Fluid    [PDF]

Navid Abbasi, Ali Davody

To study the rate of energy and momentum loss of a heavy quark in QGP,
specifically in the hydrodynamic regime, we use fluid/gravity duality and
construct a perturbative procedure to find the string solution in gravity side.
We show that by this construction, the position of the world-sheet horizon and
thereby the drag force exerted on the quark can be computed perturbatively,
order by order in a boundary derivative expansion, for a wide range of quark
velocities. At ideal order, our result is just the localized expression of the
drag force exerted on a moving quark in thermal plasma, while for a quark whose
velocity does not belong to the mentioned range, we predict a nonlocal drag
force. Furthermore, we apply this procedure to a transverse quark in Bjorken
flow and compute the first-derivative corrections, namely viscous corrections,
to the drag force. We show that the diffusion time depends on the initial
momentum of the transverse quark and can be about 4fm for a high energy quark
which has been created sufficiently late.

View original: http://arxiv.org/abs/1202.2737