Holographic Bjorken flow of a hot and dense fluid in the vicinity of a critical point

Abstract

In this paper we use the gauge/gravity duality to perform the first systematic study of the onset of hydrodynamic behavior in a hot and dense far-from-equilibrium strongly coupled relativistic fluid with a critical point. By employing a top-down holographic construction that stems from string theory, we numerically obtain the full nonlinear evolution of the far-from-equilibrium system undergoing a Bjorken expansion and address the following question: how does hydrodynamic behavior emerge in the vicinity of a critical point in the phase diagram? For the top-down holographic system analyzed in the present work, we find that the approach to hydrodynamics is strongly affected by the presence of the critical point: the closer the ratio between the chemical potential and the temperature is to its critical value, the longer it takes for the system to be well described by the equations of viscous hydrodynamics.

Figures (2)

• Figure 1: Holographic results for the Bjorken flow evolution of far-from-equilibrium 1RCBH backgrounds ($x_c\equiv(\mu/T)_c=\pi/\sqrt{2}$ is the critical point DeWolfe:2011tsFinazzo:2016psxCritelli:2017euk). (a) Pressure anisotropy as function of $w^{(\varepsilon)}$(dashed curves are the corresponding Navier-Stokes results). (b) Pressure anisotropy as function of $w^{(\Lambda)}$ (c) Charge density. (d) Scalar condensate.
• Figure 2: Variation of the hydrodynamization time with respect to the vanishing chemical potential case, as defined in Eq. \ref{['eq:Delta_whydro']} (the vertical asymptote indicates the location of the critical point, $x_c\equiv(\mu/T)_c=\pi/\sqrt{2}$). Results using a tolerance $tol$ of (a) $1\%$ and (b) $10\%$ in Eq. \ref{['eq:hydrodynamization']}.