First Double-Differential Cross Section Measurement of Neutral-Current π^{0} Production in Neutrino-Argon Scattering...

We report the first double-differential cross section measurement of neutral-current neutral pion (NCπ^{0}) 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 π^{0} momentum and the π^{0} scattering angle with respect to the neutrino beam. A total of 4971 candidate NCπ^{0} events fully contained within the MicroBooNE detector are selected using data collected at a mean neutrino energy of ∼0.8  GeV from 6.4×10^{20} 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 NCπ^{0} cross section, especially in the 0.2-0.5  GeV/c π^{0} 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 NCπ^{0} 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.