Weak neutral current axial form factor using (ν¯) ν -nucleon scattering and lattice QCD inputs

We present a determination of the neutral current weak axial charge GAZ(0)=−0.654(3)stat(5)sys using the strange quark axial charge GAs(0) calculated with lattice QCD. We then perform a phenomenological analysis, where we combine the strange quark electromagnetic form factor from lattice QCD with (anti)neutrino-nucleon scattering differential cross section from MiniBooNE experiments in a momentum transfer region 0.24 ≲ Q² ≲ 0.71 GeV² to determine the neutral current weak axial form factor GAZ(Q2) in the range of 0 ≲ Q² ≤ 1 GeV². This yields a phenomenological value of GAZ(0) = −0.687(89)_stat(40)_sys. The value of GAZ(0) constrained by the lattice QCD calculation of GAs(0), when compared to its phenomenological determination, provides a significant improvement in precision and accuracy and can be used to provide a constraint on the fit to GAZ(Q2) for Q²> 0. This constrained fit leads to an unambiguous determination of (anti)neutrino-nucleon neutral current elastic scattering differential cross section near Q² = 0 and can play an important role in numerically isolating nuclear effects in this region. We show a consistent description of GAZ(Q2) obtained from the (anti)neutrino-nucleon scattering cross section data requires a nonzero contribution of the strange quark electromagnetic form factor. We demonstrate the robustness of our analysis by providing a post-diction of the BNL E734 experimental data.