Short-Baseline Electron Neutrino Disappearance, Tritium Beta Decay and Neutrinoless Double-Beta Decay

TL;DR

This paper investigates short-baseline electron neutrino disappearance through 3+1 neutrino mixing models, analyzing anomalies from MiniBooNE, Gallium experiments, and reactor data, and explores implications for beta-decay and neutrinoless double-beta decay.

Contribution

It provides a combined fit of multiple neutrino oscillation data sets within 3+1 schemes, suggesting possible mass and mixing parameters and potential differences between neutrino and antineutrino sectors.

Findings

Combined fit indicates Delta m^2 >~ 0.1 eV^2 and sin^2 2 theta between 0.11 and 0.48.

Reactor and Tritium data constrain sin^2 2 theta below 0.10.

Predicted contributions to beta-decay and neutrinoless double-beta decay are within specific eV ranges.

Abstract

We consider the interpretation of the MiniBooNE low-energy anomaly and the Gallium radioactive source experiments anomaly in terms of short-baseline electron neutrino disappearance in the framework of 3+1 four-neutrino mixing schemes. The separate fits of MiniBooNE and Gallium data are highly compatible, with close best-fit values of the effective oscillation parameters Delta m^2 and sin^2 2 theta. The combined fit gives Delta m^2 >~ 0.1 eV^2 and 0.11 < sin^2 2 theta < 0.48 at 2 sigma. We consider also the data of the Bugey and Chooz reactor antineutrino oscillation experiments and the limits on the effective electron antineutrino mass in beta-decay obtained in the Mainz and Troitsk Tritium experiments. The fit of the data of these experiments limits the value of sin^2 2 theta below 0.10 at 2 sigma. Considering the tension between the neutrino MiniBooNE and Gallium data and the antineutrino reactor and Tritium data as a statistical fluctuation, we perform a combined fit which gives Delta m^2 \simeq 2 eV and 0.01 < sin^2 2 theta < 0.13 at 2 sigma. Assuming a hierarchy of masses m_1, m_2, m_3 << m_4, the predicted contributions of m_4 to the effective neutrino masses in beta-decay and neutrinoless double-beta-decay are, respectively, between about 0.06 and 0.49 and between about 0.003 and 0.07 eV at 2 sigma. We also consider the possibility of reconciling the tension between the neutrino MiniBooNE and Gallium data and the antineutrino reactor and Tritium data with different mixings in the neutrino and antineutrino sectors. We find a 2.6 sigma indication of a mixing angle asymmetry.