Implications of sterile neutrinos for medium/long-baseline neutrino experiments and the determination of $\theta_{13}$

TL;DR

This paper examines how sterile neutrinos could influence medium and long-baseline neutrino experiments, potentially altering measurements of key parameters like  and , and discusses the consistency of recent data with sterile neutrino models.

Contribution

It provides a comprehensive analysis of sterile neutrino effects on neutrino oscillation measurements and explores their implications for current and future experiments.

Findings

Sterile neutrinos can significantly modify  measurements in appearance experiments.

Reactor experiments are less affected by sterile neutrinos, maintaining consistent  values.

T2K results imply a lower bound on  in the +2 scenario, within future experimental sensitivities.

Abstract

We revisit some of the recent neutrino observations and anomalies in the context of sterile neutrinos. Based on a general parametrization motivated in the presence of sterile neutrinos, the consistency of the MINOS disappearance data with additional sterile neutrinos is discussed. We also explore the implications of sterile neutrinos for the measurement of $|U_{\mu3}|$ in this case. Regarding the determination of $|U_{e3}|$, we observe that the existence of sterile neutrinos may induce a significant modification of the $\theta_{13}$ angle in neutrino appearance experiments like T2K and MINOS, over and above the ambiguities and degeneracies that are already present in 3-neutrino parameter extractions. The modification is less significant in reactor neutrino experiments like Double-CHOOZ, Daya Bay and RENO and therefore the extracted $|U_{e3}|$ value when sterile neutrinos are present is close to the one that would be obtained in the 3-neutrino case. We also conclude that the results from T2K imply a 90% C.L. lower-bound on $|U_{e3}|$, in the "$\,3+2$" neutrino case, which is still within the sensitivity of future reactor neutrino experiments like Daya Bay, and consistent with the one-$\sigma$ range of $\sin^22\theta_{13}$ recently reported by the Double-CHOOZ experiment. Finally, we argue that for the recently determined best-fit parameters, the results in the "$\,3+1$" scenario would be very close to the medium/long baseline results obtained in the "$\,3+2$" case analyzed in this work.