Very-short-baseline electron neutrino disappearance

Abstract

We consider possible indications of very-short-baseline (VSBL) electron neutrino disappearance into sterile neutrinos in MiniBooNE neutrino data and Gallium radioactive source experiments. We discuss the compatibility of such a disappearance with reactor and MiniBooNE antineutrino data. We find a tension between neutrino and antineutrino data which could be due to: (1) statistical fluctuations; (2) underestimate of systematic uncertainties; (3) exclusion of our hypothesis of very-short-baseline ${\ensuremath{\nu}}_{e}$ disappearance; (4) a violation of $CPT$ symmetry. Considering the first possibility, we present the results of a combined fit of all data, which indicate that ${P}_{{\ensuremath{\nu}}_{e}\ensuremath{\rightarrow}{\ensuremath{\nu}}_{e}}<1$ with 97.04% CL. We consider also the possibility of $CPT$ violation, which leads to the best-fit value ${A}_{ee}^{CPT,\mathrm{bf}}=\ensuremath{-}0.17$ for the asymmetry of the ${\ensuremath{\nu}}_{e}$ and ${\overline{\ensuremath{\nu}}}_{e}$ survival probabilities and ${A}_{ee}^{CPT}<0$ at 99.71% CL.