# Nucleon axial, scalar, and tensor charges using lattice QCD at the physical pion mass

## TL;DR

This paper presents lattice QCD calculations of nucleon isovector axial, scalar, and tensor charges at the physical pion mass, using multiple ensembles and analysis methods to control excited-state effects and systematic uncertainties.

## Contribution

It provides the first comprehensive lattice QCD determination of nucleon charges at the physical pion mass with detailed analysis of excited states and renormalization scheme dependencies.

## Key findings

- Tensor charge: 0.972(41) with 4% uncertainty
- Axial charge: 1.265(49) with 4% uncertainty
- Scalar charge: 0.927(303) with larger uncertainty

## Abstract

We report on lattice QCD calculations of the nucleon isovector axial, scalar, and tensor charges. Our calculations are performed on two 2+1-flavor ensembles generated using a 2-HEX-smeared Wilson-clover action at the physical pion mass and lattice spacings $a\approx$ 0.116 and 0.093 fm. We use a wide range of source-sink separations - eight values ranging from roughly 0.4 to 1.4 fm on the coarse ensemble and three values from 0.9 to 1.5 fm on the fine ensemble - which allows us to perform an extensive study of excited-state effects using different analysis and fit strategies. To determine the renormalization factors, we use the nonperturbative Rome-Southampton approach and compare RI'-MOM and RI-SMOM intermediate schemes to estimate the systematic uncertainties. Our final results are computed in the MS-bar scheme at scale 2 GeV. The tensor and axial charges have uncertainties of roughly 4%, $g_T=0.972(41)$ and $g_A=1.265(49)$. The resulting scalar charge, $g_S=0.927(303)$, has a much larger uncertainty due to a stronger dependence on the choice of intermediate renormalization scheme and on the lattice spacing.