The gallium anomaly revisited

Abstract

The gallium anomaly, i.e. the missing electron-neutrino flux from 37Ar and 51Cr 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 3.0σ to 2.3σ. This result is compatible with the recent indication in favor of short-baseline ν¯e disappearance due to small active-sterile neutrino mixing obtained from the combined analysis of the data of the NEOS and DANSS reactor experiments. Keywords: Gallium anomaly, Charged-current cross-sections, Nuclear shell model, Neutrino-nucleus interactions