Pion Production in High-Energy Neutrino Reactions with Nuclei

Abstract: [Background] A quantitative understanding of neutrino interactions with nuclei is needed for precision era neutrino long baseline experiments (MINOS, NOvA, DUNE) which all use nuclear targets. Pion production is the dominant reaction channel at the energies of these experiments. [Purpose] Investigate the influence of nuclear effects on neutrino-induced pion production cross sections and compare predictions for pion-production with available data. [Method] The Giessen Boltzmann--Uehling--Uhlenbeck (GiBUU) model is used for the description of all incohrent channels in neutrino-nucleus reactions. [Results] Differential cross sections for charged and neutral pion production for the MINER$\nu$A neutrino and antineutrino flux are calculated. An estimate for the coherent cross section is obtained from a comparison of data with theoretical results. The invariant mass ($W$) distribution of the $\Delta$ resonances produced is analyzed. [Conclusions] Final state interactions affect the pion kinetic energy spectra significantly. The data for charged pion production at MINER$\nu$A are compatible with the results of calculations using elementary data taken from an old Argonne National Laboratory experiment. Remaining differences can be attributed to coherent production; the data for antineutrino induced neutral pion production, where no coherent contribution is present, are reproduced quite well. In contrast, the MiniBooNE data, taken at a lower energy, are consistently higher than the theoretical description. The analysis of $W$-distributions shows that experimental cuts on this quantity lead to shape distortions for nuclear targets.