Second-Order Hydrodynamics in Next-to-Leading-Order QCD.

Jacopo Ghiglieri,Derek Teaney,Guy D Moore

doi:10.1103/physrevlett.121.052302

Abstract

We compute the hydrodynamic relaxation times τ_{π} and τ_{j} for hot QCD at next-to-leading order in the coupling with kinetic theory. We show that certain dimensionless ratios of second-order to first-order transport coefficients obey bounds which apply whenever a kinetic theory description is possible; the computed values lie somewhat above these bounds. Strongly coupled theories with holographic duals strongly violate these bounds, highlighting their distance from a quasiparticle description.

Highlights

Introduction.—The quark-gluon plasma (QGP) produced at RHIC [1,2] and the LHC [3,4,5,6] appears to be an excellent fluid
In addition to finding concrete results for K and τj=Dq, we will show very general bounds on these dimensionless ratios which follow as soon as we state that a theory is well described by relativistic kinetic theory
In Ref. [14], we have introduced in great detail a linearized collision operator to “(almost) next-to-leading order (NLO),” (Corrections which lie beyond the kinetic theory picture arise at still higher order.) 2 ↔ 2 elastic scatterings and effective 1 ↔ 2 inelastic scatterings contribute to the leading order (LO) collision operator, the former taking the lion’s share

Summary

Introduction

Introduction.—The quark-gluon plasma (QGP) produced at RHIC [1,2] and the LHC [3,4,5,6] appears to be an excellent fluid. We extended previous perturbative results for the shear viscosity and baryon-number diffusion of hot QCD from leading [13] to next-to-leading order (NLO) [14]; see Fig. 1.

Results

Conclusion