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

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.

24 pages, 13 figures, 9 tables. v2: added references. v3: additional discussion of systematics and summary plot showing calculations by other groups

References in corpus (7)

• Adaptive multigrid algorithm for the lattice Wilson-Dirac operator
• Nucleon isovector couplings from $N_f=2$ lattice QCD
• Massless correlators of vector, scalar and tensor currents in position space at orders alpha_s^3 and alpha_s^4: explicit analytical results
• RI'/SMOM scheme amplitudes for quark currents at two loops
• Fourier Accelerated Conjugate Gradient Lattice Gauge Fixing
• Chiral Corrections to Nucleon Two- and Three-Point Correlation Functions
• Chiral perturbation theory and nucleon-pion-state contaminations in lattice QCD

Cited by in corpus (3)

• CP violating effects in ${}^{210}$Fr and prospects for new physics beyond the Standard Model
• Excited states in nucleon structure calculations
• Off-shell quark bilinear operator Green's functions at two loops