Transport near the chiral critical point

TL;DR

This paper investigates how fluctuations near the QCD chiral critical point affect transport properties and soft pion production in heavy ion collisions, providing explanations for experimental excesses.

Contribution

It introduces stochastic hydrodynamic equations to model fluctuation effects near the critical point and estimates their impact on observable particle yields.

Findings

Enhanced fluctuations modify transport coefficients.

Critical fluctuations can explain excess soft pions.

Provides a framework for connecting critical phenomena to experimental data.

Abstract

The evolution of a heavy ion collision passes close to the O(4) critical point of QCD, where fluctuations of the order parameter are expected to be enhanced. Using the appropriate stochastic hydrodynamic equations in mean field near the the pseudo-critical point, we compute how these enhanced fluctuations modify the transport coefficients of QCD. Finally, we estimate the expected critical enhancement of soft pion yields, which provides a plausible explanation for the excess seen in experiment relative to ordinary hydrodynamic computations.