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Search for Electron Antineutrino Appearance in a Long-Baseline Muon Antineutrino Beam
1University of Tokyo, Institute for Cosmic Ray Research, Kamioka Observatory, Kamioka, Japan.
Abstract:
Electron antineutrino appearance is measured by the T2K experiment in an accelerator-produced antineutrino beam, using additional neutrino beam operation to constrain parameters of the Pontecorvo-Maki-Nakagawa-Sakata (PMNS) mixing matrix. T2K observes 15 candidate electron antineutrino events with a background expectation of 9.3 events. Including information from the kinematic distribution of observed events, the hypothesis of no electron antineutrino appearance is disfavored with a significance of 2.40σ and no discrepancy between data and PMNS predictions is found. A complementary analysis that introduces an additional free parameter which allows non-PMNS values of electron neutrino and antineutrino appearance also finds no discrepancy between data and PMNS predictions.
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Alpha (α) decay is the emission of an α particle from the nucleus. For example, polonium-210 undergoes α decay:

