The gallium anomaly revisited

Abstract

The gallium anomaly, i.e. the missing electron-neutrino flux from ${}^{37}$Ar and ${}^{51}$Cr electron-capture decays as measured by the GALLEX and SAGE solar-neutrino detectors, has been among us already for about two decades. We present here a new estimate of the significance of this anomaly based on cross-section calculations using nuclear shell-model wave functions obtained by exploiting recently developed two-nucleon interactions. The gallium anomaly of the GALLEX and SAGE experiments is found to be smaller than that obtained in previous evaluations, decreasing the significance from 3.0$\sigma$ to 2.3$\sigma$. This result is compatible with the recent indication in favor of short-baseline ${\bar{\nu }}_e$ disappearance due to small active-sterile neutrino mixing obtained from the combined analysis of the data of the NEOS and DANSS reactor experiments.