Signs of nonmonotonic finite-volume corrections to g A

We study finite-volume (FV) corrections to determinations of g A via lattice quantum chromodynamics (QCD) using analytic results and numerical analysis. We observe that S U ( 2 ) heavy Baryon chiral perturbation theory does not provide an unambiguous prediction for the sign of the FV correction, which is not surprising when one also considers large- N c constraints on the axial couplings. We further show that nonmonotonic FV corrections are naturally allowed when one considers either including explicit Δ -resonance degrees of freedom or one works to higher orders in the chiral expansion. We investigate the potential impact of these FV corrections with a precision study of g A using models of FV corrections that are monotonic and nonmonotonic. Using lattice QCD data that is approximately at the 1% level of precision, we do not see significant evidence of nonmonotonic corrections. Looking forward to the next phase of lattice QCD calculations, we estimate that calculations that are between the 0.1% and 1% level of precision may be sensitive to these FV artifacts. Finally, we present an update of the CalLat prediction of g A in the isospin limit with subpercent precision, g A QCD = 1.2674 ( 96 ) .