Neutron matter at finite temperature

TL;DR

This paper computes the neutron matter equation of state at finite temperature using low-momentum nuclear interactions, comparing results with virial and variational calculations to inform astrophysical models.

Contribution

It introduces a loop expansion approach around Hartree-Fock energy for finite-temperature neutron matter with low-momentum interactions, including normal and anomalous diagrams.

Findings

Good agreement with virial EOS at low density

Provides estimates for theoretical uncertainties

Applicable for densities below saturation and T <= 10 MeV

Abstract

We calculate the neutron matter equation of state at finite temperature based on low-momentum two- and three-nucleon interactions. The free energy is obtained from a loop expansion around the Hartree-Fock energy, including contributions from normal and anomalous diagrams. We focus on densities below saturation density with temperatures T <= 10 MeV and compare our results to the model-independent virial equation of state and to variational calculations. Good agreement with the virial equation of state is found at low density. We provide simple estimates for the theoretical error, important for extrapolations to astrophysical conditions.