Trapped surfaces in a hadronic fluid

TL;DR

This paper models pion propagation in a non-uniform hadronic fluid as a scalar field in curved spacetime, revealing horizon-like structures analogous to those in general relativity and deriving an expression for surface gravity.

Contribution

It introduces a novel analogy between pion propagation in a hadronic fluid and scalar fields in curved spacetime, including horizon and surface gravity concepts.

Findings

Identification of trapping horizons in the fluid

Derivation of an analog surface gravity

Equivalence of wave equation to scalar field in curved spacetime

Abstract

Pion propagation in a hadronic fluid with a non-homogeneous relativistic flow is studied in terms of the linear sigma model. The wave equation turns out to be equivalent to the equation of motion for a massless scalar field propagating in a curved spacetime geometry. The metric tensor depends locally on the soft pion dispersion relation and the four-velocity of the fluid. For a relativistic flow in curved spacetime the apparent and trapping horizons may be defined in the same way as in general relativity. An expression for the analog surface gravity is derived.