An anomalous measurement of delta m31 squared from neutrino oscillations at the Daya Bay Reactor Neutrino Experiment

Abstract

In 2012, the collaboration overseeing the Daya Bay Reactor Neutrino Experiment announced results which determined the magnitude of the mixing angle \theta_{13} with unprecedented precision. However, no attempt was made in the collaboration’s publications to predict the value of the most relevant mass-squared difference to the observed oscillation, \delta m^2_{31}. This paper presents the results of an analysis which suggests that the Daya Bay data prefers a value of \delta m^2_{31} which is far greater than its presently recognized value. Specifically, it is found that Daya Bay predicts \delta m^2_{31} = 3.53_(-1.07)^(+.74) × 10^(-3) eV^2, where the cited uncertainties correspond to the 99% confidence bounds. This measurement excludes the most precise current measurement of \delta m^2_{31}, the MINOS result, at a 99% confidence level and is in turn excluded by the MINOS data at a 10 \sigma level. The possibility that sterile neutrino effects are the cause of this anomalous result is considered and used to suggest further work.