First Double-Differential Cross Section Measurement of Neutral-Current π0 Production in Neutrino-Argon Scattering in the MicroBooNE Detector

Abstract

We report the first double-differential cross section measurement of neutral-current neutral pion (NCπ0) production in neutrino-argon scattering, as well as single-differential measurements of the same channel in terms of final states with and without protons. The kinematic variables of interest for these measurements are the π0 momentum and the π0 scattering angle with respect to the neutrino beam. A total of 4971 candidate NCπ0 events fully contained within the MicroBooNE detector are selected using data collected at a mean neutrino energy of ∼0.8 GeV from 6.4×1020 protons on target from the Booster Neutrino Beam at the Fermi National Accelerator Laboratory. After extensive data-driven model validation to ensure unbiased unfolding, the Wiener-singular-value-decomposition method is used to extract nominal flux-averaged cross sections. The results are compared to predictions from commonly used neutrino event generators, which tend to overpredict the measured NCπ0 cross section, especially in the 0.2-0.5 GeV/c π0 momentum range and at forward scattering angles. Events with at least one proton present in the final state are also underestimated. This data will help improve the modeling of NCπ0 production, which represents a major background in measurements of charge-parity violation in the neutrino sector and in searches for new physics beyond the standard model.