Deuterium target data for precision neutrino-nucleus cross sections

Amplitudes derived from scattering data on elementary targets are basic inputs to neutrino-nucleus cross section predictions. A prominent example is the isovector axial nucleon form factor, F-A(q(2)), which controls charged current signal processes at accelerator-based neutrino oscillation experiments. Previous extractions of F-A from neutrino-deuteron scattering data rely on a dipole shape assumption that introduces an unquantified error. A new analysis of world data for neutrino-deuteron scattering is performed using a model-independent, and systematically improvable, representation of FA. A complete error budget for the nucleon isovector axial radius leads to r(A)(2) = 0.46(22) m(2), with a much larger uncertainty than determined in the original analyses. The quasielastic neutrino-neutron cross section is determined as sigma(v(mu)n -> mu(-)p)vertical bar E-nu=1 GeV = 10.1(0.9) x 10(-39) cm(2). The propagation of nucleon-level constraints and uncertainties to nuclear cross sections is illustrated using MINERvA data and the GENIE event generator. These techniques can be readily extended to other amplitudes and processes.