The fate of nonlinear perturbations near the QCD critical point

TL;DR

This paper investigates how the QCD critical point influences nonlinear wave propagation in hydrodynamics, revealing significant damping effects that could serve as experimental signals of the critical endpoint.

Contribution

It introduces a framework incorporating the QCD critical point into second-order causal dissipative hydrodynamics to study nonlinear wave behavior near the critical point.

Findings

Nonlinear waves are significantly damped near the critical point.

Damping may cause the disappearance of Mach cone effects.

Enhanced fluctuations in flow coefficients are observed near the critical point.

Abstract

The impact of the QCD critical point on the propagation of nonlinear waves has been studied. The effects have been investigated within the scope of second-order causal dissipative hydrodynamics by incorporating the critical point into the equation of state, and the scaling behaviour of transport coefficients and of thermodynamic response functions. Near the critical point, the nonlinear waves are found to be significantly damped which may result in the disappearance of the Mach cone effects of the away side jet. Such damping may lead to enhancement in the fluctuations of elliptic and higher flow coefficients. Therefore, the disappearance of Mach cone effects and the enhancement of fluctuations in flow harmonics in the event-by-event analysis may be considered as signals of the critical endpoint.