Equilibration and hydrodynamics at strong and weak coupling

Abstract

We give an updated overview of both weak and strong coupling methods to describe the approach to a plasma described by viscous hydrodynamics, a process now called hydrodynamisation. At weak coupling the very first moments after a heavy ion collision is described by the colour-glass condensate framework, but quickly thereafter the mean free path is long enough for kinetic theory to become applicable. Recent simulations indicate thermalization in a time $t\sim 40(\eta /s{)}^{4/3}/T$ [1], with $T$ the temperature at that time and $\eta /s$ the shear viscosity divided by the entropy density. At (infinitely) strong coupling it is possible to mimic heavy ion collisions by using holography, which leads to a dual description of colliding gravitational shock waves. The plasma formed hydrodynamises within a time of $0.41/T$. A recent extension found corrections to this result for finite values of the coupling, when $\eta /s$ is bigger than the canonical value of $1/4\pi$, which leads to $t\sim (0.41+1.6(\eta /s-1/4\pi ))/T$ [2]. Future improvements include the inclusion of the effects of the running coupling constant in QCD.

7 pages, 4 figures, talk presented at Quark Matter 2017 (Chicago)

References in corpus (6)

• Horizon formation and far-from-equilibrium isotropization in supersymmetric Yang-Mills plasma
• Holography and colliding gravitational shock waves in asymptotically AdS_5 spacetime
• Particle spectra and HBT radii for simulated central nuclear collisions of C+C, Al+Al, Cu+Cu, Au+Au, and Pb+Pb from Sqrt(s)=62.4-2760 GeV
• Paths to equilibrium in non-conformal collisions
• Broken boost invariance in the Glasma via finite nuclei thickness
• Time evolution of linearized gauge field fluctuations on a real-time lattice

Cited by in corpus (2)

• Black hole scrambling from hydrodynamics
• The Cosmological Heavy Ion Collider: Fast Thermalization after Cosmic Inflation