Nucleon structure from 2+1f dynamical DWF lattice QCD at nearly physical pion mass

TL;DR

This paper reports on nucleon structure calculations using 2+1-flavor dynamical DWF lattice QCD at near-physical pion masses, analyzing form factors and structure functions with large volumes and controlled chiral symmetry breaking.

Contribution

It provides new lattice QCD results at near-physical pion masses with large volumes, confirming finite-size effects in isovector axial form factors.

Findings

Finite-size effects observed in axial charge

Agreement with previous heavier pion mass results

Large volume reduces finite-size artifacts

Abstract

Current status of nucleon structure calculations with joint RBC and UKQCD 2+1-flavor dynamical domain-wall fermions (DWF) lattice QCD is reported: Two ensembles with pion mass of about (m_\pi=170) MeV and 250 MeV are used. The lattice cutoff is set at about 1.4 GeV, allowing a large spatial volume of about (L=4.6) fm across while maintaining a sufficiently small residual breaking of chiral symmetry with the dislocation-suppressing-determinant-ratio (DSDR) gauge action. We calculate all the isovector form factors and some low moments of isovector structure functions. We confirm the finite-size effect in isovector axialvector-current form factors, in particular the deficit in the axial charge and its scaling in terms of (m_\pi L), that we reported from our earlier calculation at heavier pion masses.