Moat Regimes in QCD and their Signatures in Heavy-Ion Collisions

TL;DR

This paper explores spatially modulated dense QCD phases called moat regimes, their signatures in heavy-ion collisions, and introduces the concept of a quantum pion liquid as a new state of matter.

Contribution

It introduces the quantum pion liquid and analyzes how moat regimes can be identified through particle spectra and correlations in heavy-ion collision experiments.

Findings

Particle production peaks at nonzero momentum in moat regimes

Particle correlations increase significantly at nonzero momentum

Moat regimes can serve as indicators of inhomogeneous QCD phases

Abstract

Dense QCD matter can exhibit spatially modulated regimes. They can be characterized by particles with a moat spectrum, where the minimum of the energy is over a sphere at nonzero momentum. Such a moat regime can either be a precursor for the formation inhomogeneous condensates, or signal a quantum pion liquid. We introduce the quantum pion liquid and discuss the underlying physics of the moat regime based on studies in low-energy models and preliminary results in QCD. Heavy-ion collisions at small beam energies have the potential to reveal the rich phase structure of QCD at low temperature and nonzero density. We show how moat regimes can be discovered through such collisions. Particle production is enhanced at the bottom of the moat, resulting in a peak at nonzero momentum, instead of zero, in the particle spectrum. Particle number correlations can even increase by several orders of magnitude at nonzero momentum in the moat regime.