Many-body perturbation theory for the nuclear equation of state up to fifth order

TL;DR

This paper introduces a GPU-accelerated, automated framework for high-order many-body perturbation theory calculations of the nuclear equation of state, enabling precise, systematic studies of nuclear matter relevant to neutron stars.

Contribution

The authors develop an automated, GPU-accelerated computational framework for fifth-order MBPT in nuclear physics, including all diagrams and residual three-body contributions, advancing high-order perturbative calculations.

Findings

MBPT converges up to fifth order in neutron and symmetric nuclear matter.

The framework accurately evaluates all 840 fifth-order diagrams with controlled uncertainties.

Results provide insights into neutron star matter and asymmetric nuclear matter.

Abstract

We present an automated, GPU-accelerated framework for many-body perturbation theory (MBPT) calculations of the zero-temperature nuclear equation of state (EOS) based on chiral nucleon-nucleon (NN) and three-nucleon (3N) interactions. Automated diagram generation and evaluation enable the computation of all diagrams up to fifth order in the MBPT expansion at the normal-ordered two-body level in infinite matter, with residual three-body contributions explicitly included up to third order. Multi-GPU acceleration of 3N normal ordering, a novel Monte Carlo integrator (called PVegas), and further advances in high-performance computing enable us to evaluate all 840 fifth-order diagrams with controlled numerical uncertainties. We investigate the MBPT convergence up to fifth order in pure neutron matter (PNM) and symmetric nuclear matter (SNM) for two sets of chiral interactions, study neutron star matter, and present fourth-order results for asymmetric matter including normal-ordered 3N forces. The framework enables systematic MBPT studies with harder interactions and benchmarks against nonperturbative methods. It can be further extended to finite-temperature EOS calculations and to improved uncertainty quantification using emulation and resummation techniques.