Hyperon Puzzle: Hints from Quantum Monte Carlo Calculations

TL;DR

This paper uses Quantum Monte Carlo calculations to explore how hyperons affect neutron star properties, highlighting the importance of three-body forces and the need for better constraints to resolve the hyperon puzzle.

Contribution

It demonstrates the critical role of three-body hyperon-nucleon interactions in neutron star equations of state using Quantum Monte Carlo methods.

Findings

Three-body hyperon-nucleon interactions significantly influence neutron star maximum mass.

Different models of three-body forces yield contrasting maximum mass predictions.

Results suggest hyperons may not be incompatible with massive neutron stars.

Abstract

The onset of hyperons in the core of neutron stars and the consequent softening of the equation of state have been questioned for a long time. Controversial theoretical predictions and recent astrophysical observations of neutron stars are the grounds for the so-called hyperon puzzle. We calculate the equation of state and the neutron star mass-radius relation of an infinite systems of neutrons and $\Lambda$ particles by using the auxiliary field diffusion Monte Carlo algorithm. We find that the three-body hyperon-nucleon interaction plays a fundamental role in the softening of the equation of state and for the consequent reduction of the predicted maximum mass. We have considered two different models of three-body force that successfully describe the binding energy of medium mass hypernuclei. Our results indicate that they give dramatically different results on the maximum mass of neutron stars, not necessarily incompatible with the recent observation of very massive neutron stars. We conclude that stronger constraints on the hyperon-neutron force are necessary in order to properly assess the role of hyperons in neutron stars.