  Gallium radioactive source experiments have reported a neutrino-induced event
rate about 20\% lower than expected with a high statistical significance. We
present an explanation of this observation assuming quantum decoherence of the
neutrinos in the gallium detectors at a scale of 2~m. This explanation is
consistent with global data on neutrino oscillations, including solar
neutrinos, if decoherence effects decrease quickly with energy, for instance
with a power law $E_\nu^{-r}$ with $r\simeq 12$. Our proposal does not require
the presence of sterile neutrinos but implies a modification of the standard
quantum mechanical evolution equations for active neutrinos.

High Energy Physics - Phenomenology;High Energy Physics - Experiment