Tripling Fluctuations and Peaked Sound Speed in Fermionic Matter

TL;DR

This paper investigates a three-fermion cluster crossover in dense matter, revealing how tripling fluctuations influence the equation of state and sound speed, with implications for neutron star physics.

Contribution

It introduces a novel analysis of tripling fluctuations and their effects on dense fermionic matter, connecting cluster formation to observable astrophysical phenomena.

Findings

Non-monotonic momentum distributions of baryon-like clusters

Peaked sound speed at finite densities

Relevance to neutron star equations of state

Abstract

A crossover involving three-fermion clusters is relevant to the hadron-quark crossover, which, if occurring in a neutron star, could naturally reproduce the dense-matter equation of state recently deduced from simultaneous observations of neutron-star masses and radii. To understand the crossover mechanism, we examine the role of tripling fluctuations induced by the formation of three-fermion clusters. The phase-shift representation of fluctuations manifests an interplay of bound and scattering states, leading to non-monotonic momentum distributions of baryon-like clusters and peaked sound speed at finite densities. We demonstrate them by applying our approach to a nonrelativistic system of one-dimensional three-color fermions analogous to the hadron-quark matter.