We have applied a microscopic model for single photon emission in neutral current interactions on nucleons and nuclei to determine the number and distributions of such events at the Super-Kamiokande detector, for the flux and beam exposure of the T2K experiment in neutrino mode. These reactions represent an effectively irreducible background in electron-(anti)neutrino appearance measurements aimed at a precise measurement of mixing angle ${\theta }_{13}$ and the $CP$ violating phase. We have obtained a total number of photon events that is twice as large as the one from the NEUT event generator (version 5.1.4.2) used in the analysis of T2K data. Detailed comparisons of energy and angular distributions for the ${\nu }_{\mu }$ and ${\overline{\nu }}_{\mu }$ fluxes have also been performed.

• Received 16 July 2015

DOI:https://doi.org/10.1103/PhysRevD.92.053005