Decoherence, matter effect, neutrino hierarchy signature in long baseline experiments

Abstract

Environmental decoherence of oscillating neutrinos of strength $\Gamma =(2.3\pm 1.1)\times 10^{-23}$ GeV can explain how maximal ${\theta }_{23}$ mixing observed at 295 km by T2K appears to be non-maximal at longer baselines. As shown recently by R. Oliveira, the MSW matter effect for neutrinos is altered by decoherence: In normal (inverted) mass hierarchy, a resonant enhancement of ${\nu }_{\mu }({\bar{\nu }}_{\mu })\to {\nu }_e({\bar{\nu }}_e)$ occurs for $6<E_{\nu }<20$ GeV. Thus decoherence at the rated strength may be detectable as an excess of charged-current ${\nu }_e$ events in the full ${\nu }_{\mu }$ exposures of MINOS+ and OPERA.

Comments: 8 pages, 2 figures Accepted for publication in PRD