# Quark Matter 2017

5-11 February 2017
Hyatt Regency Chicago
America/Chicago timezone

## The x and scale dependence of the transport coefficient $\hat{q}$

8 Feb 2017, 08:50
20m
Regency D

### Regency D

Oral Jets and High pT Hadrons

### Speaker

Amit Kumar (Wayne State University)

### Description

We take a closer look at the single particle nuclear modification factor ($R_{AA}$) and azimuthal anisotropy ($v_{2}$) of
leading hadrons at high transverse momentum ($p_{T}$) at both RHIC and LHC collision energies. We focus on the
established reduction in the interaction measure $\hat{q}/T^{3}$ between RHIC and LHC, as discovered by the JET
collaboration. The centrality dependence of the $R_{AA}$ and $v_{2}$ at both these collision energies strongly suggests
that the reduction is not caused by a temperature dependence in the ratio of $\hat{q}/T^{3}$ but rather by an energy
dependence of $\hat{q}$.
We study this dependence by introducing an $x$ dependence in the distribution function that is integrated to obtain
$\hat{q}$. We conjecture on possible forms of a scale dependence by relating $\hat{q}$ to an object similar to a transverse
momentum dependent parton distribution function (TMDPDF). The ensuing operator product is then related to quantities
that may be estimated in lattice QCD.

Preferred Track Jets and High pT Hadrons Not applicable

### Primary author

Amit Kumar (Wayne State University)