Tuning the GENIE Pion Production Model with MINERvA Data

Faced with unresolved tensions between neutrino interaction measurements at few-GeV neutrino energies, current experiments are forced to accept large systematic uncertainties to cover discrepancies between their data and model predictions. In this paper, the widely used pion production model in GENIE is compared to four MINERvA charged current pion production measurements using NUISANCE. Tunings, ie, adjustments of model parameters, to help match GENIE to MINERvA and older bubble chamber data are presented here. We find that scattering off nuclear targets as measured in MINERvA is not in good agreement with scattering off nucleon (hydrogen or deuterium) targets in the bubble chamber data. An additional ad hoc correction for the low-$Q^2$ region, where collective effects are expected to be large, is also presented. While these tunings and corrections improve the agreement of GENIE with the data, the modeling is still far from perfect. The development of these tunings within the NUISANCE framework means that they can easily be extended to other neutrino event generator models in the future, and compared with, or adapted to include, new datasets very easily.