Resolving the Reactor Neutrino Anomaly with the KATRIN Neutrino Experiment

TL;DR

The paper discusses how the KATRIN experiment's high-resolution measurements can address the reactor neutrino anomaly by testing for sterile neutrinos at the eV mass scale, potentially confirming or ruling out their existence.

Contribution

It introduces the KATRIN experiment's sensitivity to sterile neutrinos and evaluates its potential to resolve the reactor neutrino anomaly.

Findings

Reactor data suggests possible sterile neutrinos with specific mass and mixing parameters.

KATRIN's sensitivity can test and potentially confirm or exclude these sterile neutrino hypotheses.

Upcoming experiments will clarify the existence of sterile neutrinos in the relevant parameter space.

Abstract

The KArlsruhe TRItium Neutrino experiment (KATRIN) combines an ultra-luminous molecular tritium source with an integrating high-resolution spectrometer to gain sensitivity to the absolute mass scale of neutrinos. The projected sensitivity of the experiment on the electron neutrino mass is 200 meV at 90% C.L. With such unprecedented resolution, the experiment is also sensitive to physics beyond the Standard Model, particularly to the existence of additional sterile neutrinos at the eV mass scale. A recent analysis of available reactor data appears to favor the existence of such such a sterile neutrino with a mass splitting of $|\Delta m_{\rm sterile}|^2 \ge 1.5$ eV$^2$ and mixing strength of $\sin^2{2\theta_{\rm sterile}} = 0.17\pm 0.08$ at 95% C.L. Upcoming tritium beta decay experiments should be able to rule out or confirm the presence of the new phenomenon for a substantial fraction of the allowed parameter space.