Search for short baseline $\hat{I}{½}_e$ disappearance with the T2K near detector

Abstract

The T2K experiment has performed a search for $\hat{I}{½}_e$ disappearance due to sterile neutrinos using $5.9\times 10^{20}$ protons on target for a baseline of $280m$ in a neutrino beam peaked at about $500MeV$. A sample of ν_e CC interactions in the off-axis near detector has been selected with a purity of 63\% and an efficiency of 26\%. The p-value for the null hypothesis is 0.085 and the excluded region at 95\% CL is approximately $si{n}^{2}2\hat{I}{¸}_{ee}>0.3$ for $\hat{I}”m_{eff}^2>7e{V}^2/c^4$.

8 pages, 6 figures, submitted to PRD rapid communication