Extraction of the Axial Nucleon Form Factor from Neutrino Experiments on Deuterium

Abstract

We present new parameterizations of vector and axial nucleon form factors. We maintain an excellent descriptions of the form factors at low momentum transfers ($Q^2$), where the spatial structure of the nucleon is important, and use the Nachtman scaling variable $ξ$ to relate elastic and inelastic form factors and impose quark-hadron duality constraints at high $Q^2$ where the quark structure dominates. We use the new vector form factors to re-extract updated values of the axial form factor from $\numu$ experiments on deuterium. We obtain an updated world average value from $\numu$d, $\numubar$H and pion electroproduction experiments of $M_{A}$ = $1.014 \pm 0.014 GeV/c^2$. Our parameterizations are useful in modeling $ν$ interactions at low energies (e.g. for $\numu$ oscillations experiments). The predictions for high $Q^2$ can be tested in the next generation electron and $\numu$ scattering experiments.

Presented by A. Bodek at the European Physical Society Meeting, EPS2007, Manchester, England, July 2007, 4 pages, 2 figures