Analogue surface gravity near the QCD chiral phase transition

TL;DR

This paper explores how analogue surface gravity and Hawking radiation phenomena emerge near the QCD chiral phase transition by modeling pions as a scalar field in curved spacetime, revealing diverging surface gravity at the critical point.

Contribution

It introduces a relativistic acoustic geometry framework to analyze the chiral fluid near the QCD phase transition, highlighting the formation of an analogue trapped horizon and diverging surface gravity.

Findings

Analogue trapped horizon forms near the critical temperature.

Surface gravity diverges as 1/(T_c - T) approaching the critical point.

Possible observable analogue Hawking temperature near T_c.

Abstract

Using the formalism of relativistic acoustic geometry we study the expanding chiral fluid in the regime of broken chiral symmetry near the QCD chiral phase transition temperature T_c. The dynamics of pions below T_c is described by the equation of motion for a massless scalar field propagating in curved spacetime similar to an open FRW universe. The metric tensor depends locally on the soft pion dispersion relation and the four-velocity of the fluid. In the neighborhood of the critical point an analogue trapped region forms with the analogue trapped horizon as its boundary. We show that the associated surface gravity diverges near the critical point as 1/(T_c-T). Hence, if the horizon forms close to the critical temperature the analogue Hawking temperature may be comparable with or even larger than the background fluid temperature.