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Faced with unresolved tensions between neutrino interaction measurements atfew-GeV neutrino energies, current experiments are forced to accept largesystematic uncertainties to cover discrepancies between their data and modelpredictions. In this paper, the widely used pion production model in GENIE iscompared to four MINERvA charged current pion production measurements usingNUISANCE. Tunings, ie, adjustments of model parameters, to help match GENIE toMINERvA and older bubble chamber data are presented here. We find thatscattering off nuclear targets as measured in MINERvA is not in good agreementwith scattering off nucleon (hydrogen or deuterium) targets in the bubblechamber data. An additional ad hoc correction for the low-$Q^2$ region, wherecollective effects are expected to be large, is also presented. While thesetunings and corrections improve the agreement of GENIE with the data, themodeling is imperfect. The development of these tunings within the NUISANCEframeworkallows for straightforward extensions to other neutrino eventgenerators and models, and allows omitting and including new data sets as theybecome available.

Final-state kinematic imbalances are measured in mesonless production of ν_{μ}+A→μ^{-}+p+X in the MINERvA tracker. Initial- and final-state nuclear effects are probed using the direction of the μ^{-}-p transverse momentum imbalance and the initial-state momentum of the struck neutron. Differential cross sections are compared to predictions based on current approaches to medium modeling. These models underpredict the cross section at intermediate intranuclear momentum transfers that generally exceed the Fermi momenta. As neutrino interaction models need to correctly incorporate the effect of the nucleus in order to predict neutrino energy resolution in oscillation experiments, this result points to a region of phase space where additional cross section strength is needed in current models, and demonstrates a new technique that would be suitable for use in fine-grained liquid argon detectors where the effect of the nucleus may be even larger.

We present double-differential measurements of antineutrino charged-current quasielastic scattering in the MINERvA detector. This study improves on a previous single-differential measurement by using updated reconstruction algorithms and interaction models and provides a complete description of observed muon kinematics in the form of a double-differential cross section with respect to muon transverse and longitudinal momentum. We include in our signal definition zero-meson final states arising from multinucleon interactions and from resonant pion production followed by pion absorption in the primary nucleus. We find that model agreement is considerably improved by a model tuned to MINERvA inclusive neutrino scattering data that incorporates nuclear effects such as weak nuclear screening and two-particle, two-hole enhancements.

Neutrino induced coherent charged pion production on nuclei,$\overline{\nu}_\mu A\to\mu^\pm\pi^\mp A$, is a rare inelastic interaction inwhich the four-momentum squared transfered to the nucleus is nearly zero,leaving it intact. We identify such events in the scintillator of MINERvA byreconstructing |t| from the final state pion and muon momenta and by removingevents with evidence of energetic nuclear recoil or production of other finalstate particles. We measure the total neutrino and antineutrino cross sectionsas a function of neutrino energy between 2 and 20 GeV and measure fluxintegrated differential cross sections as a function of $Q^2$, $E_\pi$ and$\theta_\pi$. The $Q^2$ dependence and equality of the neutrino andanti-neutrino cross-sections at finite $Q^2$ provide a confirmation of Adler'sPCAC hypothesis.

Single neutral pion production via muon antineutrino charged-current interactions in plastic scintillator (CH) is studied using the MINERvA detector exposed to the NuMI low-energy, wideband antineutrino beam at Fermilab. Measurement of this process constrains models of neutral pion production in nuclei, which is important because the neutral-current analog is a background for ν-e appearance oscillation experiments. The differential cross sections for π0 momentum and production angle, for events with a single observed π0 and no charged pions, are presented and compared to model predictions. These results comprise the first measurement of the π0 kinematics for this process.

Single neutral pion production via muon antineutrino charged-current interactions in plastic scintillator (CH) is studied using the MINERvA detector exposed to the NuMI low-energy, wideband antineutrino beam at Fermilab. Measurement of this process constrains models of neutral pion production in nuclei, which is important because the neutral-current analog is a background for ν-e appearance oscillation experiments. The differential cross sections for π0 momentum and production angle, for events with a single observed π0 and no charged pions, are presented and compared to model predictions. These results comprise the first measurement of the π0 kinematics for this process.

Scattering of high energy particles from nucleons probes their structure, as was done in the experiments that established the non-zero size of the proton using electron beams 1 . The use of charged leptons as scattering probes enables measuring the distribution of electric charges, which is encoded in the vector form factors of the nucleon 2 . Scattering weakly interacting neutrinos gives the opportunity to measure both vector and axial vector form factors of the nucleon, providing an additional, complementary probe of their structure. The nucleon transition axial form factor, F A , can be measured from neutrino scattering from free nucleons, ν μ n → μ - p and [Formula: see text], as a function of the negative four-momentum transfer squared (Q 2 ). Up to now, F A (Q 2 ) has been extracted from the bound nucleons in neutrino-deuterium scattering 3-9 , which requires uncertain nuclear corrections 10 . Here we report the first high-statistics measurement, to our knowledge, of the [Formula: see text] cross-section from the hydrogen atom, using the plastic scintillator target of the MINERvA 11 experiment, extracting F A from free proton targets and measuring the nucleon axial charge radius, r A , to be 0.73 ± 0.17 fm. The antineutrino-hydrogen scattering presented here can access the axial form factor without the need for nuclear theory corrections, and enables direct comparisons with the increasingly precise lattice quantum chromodynamics computations 12-15 . Finally, the tools developed for this analysis and the result presented are substantial advancements in our capabilities to understand the nucleon structure in the weak sector, and also help the current and future neutrino oscillation experiments 16-20 to better constrain neutrino interaction models., (© 2023. The Author(s).)