Exploring Three-Nucleon Forces in Lattice QCD

TL;DR

This study uses lattice QCD simulations to explore three-nucleon forces, revealing short-range repulsion in the triton channel, and introduces a computationally efficient method for such investigations.

Contribution

First exploratory lattice QCD calculation of three-nucleon forces in a linear configuration using NBS wave functions.

Findings

Identified short-range repulsive three-nucleon forces in the triton channel.

Utilized a simplified linear configuration to reduce computational costs.

Discussed systematic errors affecting the results.

Abstract

Three-nucleon forces (3NF) are investigated from two-flavor lattice QCD simulations. We utilize the Nambu-Bethe-Salpeter (NBS) wave function to determine two-nucleon forces (2NF) and 3NF in the same framework. As a first exploratory study, we extract 3NF in which three nucleons are aligned linearly with an equal spacing. This is the simplest geometrical configuration which reduces the huge computational cost of calculating the NBS wave function. Quantum numbers of the three-nucleon system are chosen to be (I, J^P)=(1/2,1/2^+) (the triton channel). Lattice QCD simulations are performed using N_f=2 dynamical clover fermion configurations at the lattice spacing of a = 0.156 fm on a 16^3 x 32 lattice with a large quark mass corresponding to m_\pi= 1.13 GeV. We find repulsive 3NF at short distance in the triton channel. Several sources of systematic errors are also discussed.