QCD constraints on isospin-dense matter and the nuclear equation of state

TL;DR

This paper uses lattice QCD calculations to explore the equation of state of dense isospin matter, providing new non-perturbative bounds relevant for understanding nuclear matter in astrophysical objects.

Contribution

It offers the first rigorous non-perturbative QCD bounds on the nuclear matter equation of state across a wide density range using isospin chemical potential calculations.

Findings

Agreement with chiral perturbation theory at low chemical potential

Estimation of the superconducting gap at high chemical potential

Provision of non-perturbative bounds on nuclear matter equation of state

Abstract

Understanding the behavior of dense hadronic matter is a central goal in nuclear physics as it governs the nature and dynamics of astrophysical objects such as supernovae and neutron stars. Because of the non-perturbative nature of quantum chromodynamics (QCD), little is known rigorously about hadronic matter in these extreme conditions. Here, lattice QCD calculations are used to compute thermodynamic quantities and the equation of state of QCD over a wide range of isospin chemical potentials with controlled systematic uncertainties. Agreement is seen with chiral perturbation theory when the chemical potential is small. Comparison to perturbative QCD at large chemical potential allows for an estimate of the gap in the superconducting phase, and this quantity is seen to agree with perturbative determinations. Since the partition function for an isospin chemical potential, $\mu_I$, bounds the partition function for a baryon chemical potential $\mu_B=3\mu_I/2$, these calculations also provide rigorous non-perturbative QCD bounds on the symmetric nuclear matter equation of state over a wide range of baryon densities for the first time.