The isovector axial form factor of the nucleon from lattice QCD

Abstract

The isovector axial form factor of the nucleon plays a key role in interpreting data from long-baseline neutrino oscillation experiments. We perform a lattice-QCD based calculation of this form factor, introducing a new method to directly extract its $z$-expansion from lattice correlators. Our final parametrization of the form factor, which extends up to spacelike virtualities of $0.7{\mathrm{GeV}}^2$ with fully quantified uncertainties, agrees with previous lattice calculations but is significantly less steep than neutrino-deuterium scattering data suggests.

Comments: 6 pages + 6 pages supplementary material; (3+6) figures; 2 tables in suppl.mat