Photon emission in neutral current interactions at the T2K experiment

Understand

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 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 larger than 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 $\bar\nu_\mu$ fluxes have also been performed.