Search for neutral-current induced single photon production at the ND280 near detector in T2K

Understand

Neutrino neutral-current induced single photon production is a sub-leading order process for accelerator-based neutrino beam experiments including T2K.

• It is, however, an important process to understand because it is a background for electron (anti)neutrino appearance oscillation experiments.
• Here, we performed the first search of this process below 1 GeV using the fine-grained detector at the T2K ND280 off-axis near detector.
• By reconstructing single photon kinematics from electron-positron pairs, we achieved 95\% pure gamma ray sample from 5.738$\times 10^{20}$ protons-on-targets neutrino mode data.