A New Class of Three Nucleon Forces and their Implications

TL;DR

This paper introduces a novel class of three-nucleon forces in low-energy nuclear effective theory, showing they can significantly impact nuclear and neutron matter properties, with implications for nuclear physics and astrophysics.

Contribution

It identifies a new class of three-nucleon forces arising from pion interactions, highlighting their potential importance and the need for experimental constraints.

Findings

New three-nucleon forces can rival leading-order forces in magnitude.

The force strength depends on pion coupling to two nucleons.

Implications for nuclear structure and neutron star matter are discussed.

Abstract

We identify a new class of three-nucleon forces that arises in the low-energy effective theory of nuclear interactions including pions. We estimate their contribution to the energy of neutron and nuclear matter and find that it can be as important as the leading-order three-nucleon forces previously considered in the literature. The magnitude of this force is set by the strength of the coupling of pions to two nucleons and is presently not well constrained by experiments. The implications for nuclei, nuclear matter, and the equation of state of neutron matter are briefly discussed.