Title: SINGLE CHARGED PION PRODUCTION BY MUON NEUTRINOS IN THE MINERVA DETECTOR USING THE NUMI BEAM

Abstract: The next generation of long-baseline neutrino oscillation experiments (DUNE, Hyper-K) aims to conclusively answer the outstanding questions in neutrino oscillation physics, including the nature of lepton CP-symmetry violation and the validity of the three-neutrino paradigm. The success of this program relies on excellent beam flux simulation and precisely-known cross sections for all neutrino-nucleus scattering processes. Currently, uncertainties on these models are large, and experiments such as MINERvA, located in the NuMI neutrino beamline at Fermilab, are dedicated to reducing them. This thesis makes improvements both to flux simulation models — via reduction in hadron focusing uncertainties in the G4NuMI simulation — and to cross section knowledge via a pion production cross section measurement in the critical “transition region” between quasi-elastic and deep inelastic scattering. The cross section measurement performed is of muon neutrino charged current single charged pion production on hydrocarbon in the MINERvA detector and at mean neutrino energy of 6 GeV. The cross section is high statistics, minimally-model dependent, and measured as a function of several muon, pion, and event-wide variables, including the first measurement of the invariant hadronic mass-like variable, "W experimental", in the positive pion channel. Results are compared to the GENIE event generator and found to broadly agree, though outstanding discrepancies remain in low four-momentum transfer squared and in pion kinematics.