Particle Interferometry in a Moat Regime

TL;DR

This paper proposes that particle interferometry can detect spatially modulated phases, like the moat regime, in dense strongly interacting matter such as in heavy-ion collisions, by analyzing two-particle correlation spectra.

Contribution

It develops a field-theoretical formalism linking particle spectra to in-medium correlation functions and identifies observable signatures of the moat regime in heavy-ion collision experiments.

Findings

Two-particle spectra peak at nonzero momentum in a moat regime.

Correlation-function ratios show distinctive structures as signatures.

Proposes experimental measurement of these signatures in QCD matter.

Abstract

Dense strongly interacting matter can exhibit regimes with spatial modulations, akin to crystalline phases. In this case particles can have a moat spectrum with minimal energy at nonzero momentum. We show that particle interferometry is a sensitive probe of such a regime in heavy-ion collisions. To this end, we develop a field-theoretical formalism that relates particle spectra to in-medium real-time correlation functions of quantum fields on curved hypersurfaces of spacetime. This is then applied to the study of Bose-Einstein correlations in a moat regime in heavy-ion collisions. The resulting two-particle spectra exhibit peaks at nonzero average pair momentum, in contrast to the two-particle spectra in a normal phase, which peak at zero momentum. These peaks lead to non-trivial structures in the ratio of two-particle correlation functions, which should be experimentally measurable if the resolution in the direction of average pair momentum is sufficiently large. We propose these structures in the correlation-function ratios as clear signature of a moat regime and spatially modulated phases in quantum chromodynamics (QCD).