On SUGRA description of boost-invariant conformal plasma at strong coupling

TL;DR

This paper explores the supergravity duals of expanding boost-invariant conformal plasmas at strong coupling, deriving equilibrium properties and relaxation times through late-time asymptotic expansions, and discusses singularities in the gravitational background.

Contribution

It constructs the dual supergravity background for expanding plasmas and determines key physical quantities like equation of state and shear viscosity from the absence of singularities.

Findings

Equilibrium equation of state derived from curvature regularity.

Shear viscosity obtained from late-time expansion analysis.

Relaxation time linked to absence of pole singularities.

Abstract

We study string theory duals of the expanding boost invariant conformal gauge theory plasmas at strong coupling. The dual supergravity background is constructed as an asymptotic late-time expansion, corresponding to equilibration of the gauge theory plasma. The absence of curvature singularities in the first few orders of the late-time expansion of the dual gravitational background unambiguously determines the equilibrium equation of the state, and the shear viscosity of the gauge theory plasma. While the absence of the leading pole singularities in the gravitational curvature invariants at the third order in late-time expansion determines the relaxation time of the plasma, the subleading logarithmic singularity can not be canceled within a supergravity approximation. We comment on the possible interpretations of this singularity.