We revisit some of the recent neutrino observations and anomalies in the context of sterile neutrinos. Among our aims is to understand more clearly some of the analytic implications of the current global neutrino fits from short-baseline experiments. Of particular interest to us are the neutrino disappearance measurements from MINOS and the recent indications of a possibly nonvanishing angle, ${\theta }_{13}$, from T2K, MINOS and Double CHOOZ. 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 $|U_{\mu 3}|$ in this case. We then turn our attention to the study of $|U_{e3}|$ extraction in electron neutrino disappearance and appearance measurements. In particular, we study the effects of some of the additional $CP$ phases that appear when there are sterile neutrinos. 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 three-neutrino parameter extractions. There are reactor experiments, for instance those measuring ${\nu }_e$ disappearance like Double CHOOZ, Daya Bay and RENO, where this modification is less significant and therefore the extracted $|U_{e3}|$ value when sterile neutrinos are present is close to the one that would be obtained in the three-neutrino case. Based on our study, 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 ${sin}^{2}2{\theta }_{13}$ 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.

• Received 19 December 2011

DOI:https://doi.org/10.1103/PhysRevD.85.073004