Nuclear binding near a quantum phase transition

TL;DR

This paper presents evidence from lattice simulations that nuclear binding involves a quantum phase transition between an alpha-particle gas and a nuclear liquid, influenced by nucleon interactions, with implications for nuclear physics and astrophysics.

Contribution

It reveals a first-order quantum phase transition in nuclei and links alpha clustering to universal bosonic physics, enhancing understanding of nuclear structure.

Findings

Identified a zero-temperature first-order phase transition in nuclei.

Showed the transition depends on alpha-alpha interaction strength.

Connected nuclear states to universal bosonic physics at large scattering length.

Abstract

How do protons and neutrons bind to form nuclei? This is the central question of ab initio nuclear structure theory. While the answer may seem as simple as the fact that nuclear forces are attractive, the full story is more complex and interesting. In this work we present numerical evidence from ab initio lattice simulations showing that nature is near a quantum phase transition, a zero-temperature transition driven by quantum fluctuations. Using lattice effective field theory, we perform Monte Carlo simulations for systems with up to twenty nucleons. For even and equal numbers of protons and neutrons, we discover a first-order transition at zero temperature from a Bose-condensed gas of alpha particles (4He nuclei) to a nuclear liquid. Whether one has an alpha-particle gas or nuclear liquid is determined by the strength of the alpha-alpha interactions, and we show that the alpha-alpha interactions depend on the strength and locality of the nucleon-nucleon interactions. This insight should be useful in improving calculations of nuclear structure and important astrophysical reactions involving alpha capture on nuclei. Our findings also provide a tool to probe the structure of alpha cluster states such as the Hoyle state responsible for the production of carbon in red giant stars and point to a connection between nuclear states and the universal physics of bosons at large scattering length.