Isovector Axial Form Factor of the Nucleon from Lattice QCD

TL;DR

This paper presents a lattice QCD calculation of the nucleon's isovector axial form factor, introducing a new extraction method and providing a parameterization that aligns with previous lattice results but differs from experimental scattering data.

Contribution

A novel method to directly extract the axial form factor's z-expansion from lattice correlators is introduced, improving the analysis of nucleon structure.

Findings

Form factor parameterization up to 0.7 GeV^2 with quantified uncertainties

Agreement with previous lattice calculations

Significant discrepancy with neutrino-deuterium scattering data

Abstract

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