Measurement of Neutrino Oscillations with the MINOS Detectors in the NuMI Beam

TL;DR

The data disfavor two alternative explanations for the disappearance of neutrinos in flight: namely, neutrino decays into lighter particles and quantum decoherence of neutRinos, at the 3.7 and 5.7 standard-deviation levels, respectively.

Abstract

This letter reports new results from the MINOS experiment based on a two-year exposure to muon neutrinos from the Fermilab NuMI beam. Our data are consistent with quantum mechanical oscillations of neutrino flavor with mass splitting $|Δm^2|=(2.43\pm 0.13)\times10^{-3}$ eV$^2$ (68% confidence level) and mixing angle $\sin^2(2θ)>0.90$ (90% confidence level). Our data disfavor two alternative explanations for the disappearance of neutrinos in flight, namely neutrino decays into lighter particles and quantum decoherence of neutrinos, at the 3.7 and 5.7 standard deviation levels, respectively.

Figures (4)

• Figure 1: Energy spectra in the MINOS ND for two of the nine beam configurations before and after tuning the Monte Carlo simulation to the ND data. The data combine Run I + Run II. Both configurations are utilized in the oscillation analysis.
• Figure 2: Comparison of the FD data (points, with statistical uncertainties) from the low- and high-energy configurations with the predictions for the $\nu_\mu$ energy spectra with and without the effect of oscillations. The estimated neutral current (NC) background is indicated.
• Figure 3: Ratio of the FD data and the expected spectrum in the absence of oscillations. Also shown are the best fit curve to Eq. \ref{['eq:osc']} and the best fit to alternative models of neutrino disappearance ref:decayref:decohere. For display purposes, the data have been rebinned and the estimated oscillated NC background is subtracted.
• Figure 4: Contours for the oscillation fit to the data in Fig. \ref{['fig:spectra']}, including systematic errors. Also shown are contours from previous experiments ref:osc1ref:osc5 and our earlier result ref:minosprl.