Nuclear equation of state for arbitrary proton fraction and temperature based on chiral effective field theory and a Gaussian process emulator

TL;DR

This paper develops a nonparametric method using Gaussian process emulators to calculate the finite-temperature equation of state of asymmetric nuclear matter with chiral effective field theory, including uncertainties and properties in beta equilibrium.

Contribution

It introduces a Gaussian process-based emulator for the nuclear equation of state, enabling efficient and uncertainty-aware calculations across arbitrary proton fractions and temperatures.

Findings

Thermal pressure decreases with increasing density.

First nonparametric calculation of finite-temperature EoS in beta equilibrium.

Quantified theoretical uncertainties from many-body and chiral expansion.

Abstract

We calculate the equation of state of asymmetric nuclear matter at finite temperature based on chiral effective field theory interactions to next-to-next-to-next-to-leading order. Our results assess the theoretical uncertainties from the many-body calculation and the chiral expansion. Using a Gaussian process emulator for the free energy, we derive the thermodynamic properties of matter through consistent derivatives and use the Gaussian process to access arbitrary proton fraction and temperature. This enables a first nonparametric calculation of the equation of state in beta equilibrium, and of the speed of sound and the symmetry energy at finite temperature. Moreover, our results show that the thermal part of the pressure decreases with increasing densities.