Chiral effective field theory on the lattice at next-to-leading order

TL;DR

This study applies chiral effective field theory on the lattice at next-to-leading order to analyze nucleon-nucleon scattering, demonstrating model independence and accuracy of the approach at this order.

Contribution

It introduces a lattice implementation of chiral EFT at NLO, comparing two different LO actions to test model independence and accuracy.

Findings

Next-to-leading order results are accurate within expected higher-order corrections.

Model independence is confirmed between two different LO lattice actions.

Phase shifts and mixing angles are successfully extracted from lattice simulations.

Abstract

We study nucleon-nucleon scattering on the lattice at next-to-leading order in chiral effective field theory. We determine phase shifts and mixing angles from the properties of two-nucleon standing waves induced by a hard spherical wall in the center-of-mass frame. At fixed lattice spacing we test model independence of the low-energy effective theory by computing next-to-leading-order corrections for two different leading-order lattice actions. The first leading-order action includes instantaneous one-pion exchange and same-site contact interactions. The second leading-order action includes instantaneous one-pion exchange and Gaussian-smeared interactions. We find that in each case the results at next-to-leading order are accurate up to corrections expected at higher order.