Nucleon isovector tensor charge from lattice QCD with physical light quarks

TL;DR

This paper reports preliminary lattice QCD calculations of the nucleon isovector tensor charge using physical light quarks, providing nonperturbative renormalization and comparison with other results.

Contribution

First lattice QCD study of nucleon tensor charge with physical light quarks using nonperturbative renormalization and large-volume ensembles.

Findings

Computed renormalized tensor charge $g_T$ at 2 GeV.

Compared $g_T$ with other lattice results.

Provided preliminary estimates of scalar charge $g_S$.

Abstract

We present preliminary results for the axial, scalar and tensor charges of the nucleon measured in 2+1 flavor QCD with the physical light quarks ($m_\pi=135$ MeV). Our simulations are carried out with gauge configurations generated by the PACS Collaboration with the stout-smeared $O(a)$ improved Wilson fermions and Iwasaki gauge action at a single lattice spacing of $0.085\ (\mathrm{fm})$. There are two lattice ensembles of the PACS gauge configurations, which have physical lattice sizes over $(10\ \mathrm{fm})^4$ and $(5\ \mathrm{fm})^4$, respectively. We compute the nucleon three-point correlation functions in the axial, scalar, and tensor channels. For the renormalization, we use the Rome-Southampton method as the intermediate scheme in order to evaluate the renormalization constants for the scalar and tensor currents in fully nonperturbative manner. We then evaluate the renormalized values of the scalar and tensor charges ($g_S$ and $g_T$) in the $\overline{\rm MS}$ scheme at the renormalization scale of 2 GeV with a help of the continuum perturbation theory for the matching between two schemes. We compare our preliminary results of $g_S$ and $g_T$ with those of other collaboration results.