Measurement of the Neutrino Mass Splitting and Flavor Mixing by MINOS

Measurements of neutrino oscillations using the disappearance of muon neutrinos from the Fermilab NuMI neutrino beam as observed by the two MINOS detectors are reported. New analysis methods have been applied to an enlarged data sample from an exposure of $7.25\times {10}^{20}$ protons on target. A fit to neutrino oscillations yields values of $|\Delta m^2|=({2.32}_{-0.08}^{+0.12})\times {10}^{-3}{\mathrm{eV}}^2$ for the atmospheric mass splitting and ${sin}^2(2\theta )>0.90$ (90% C.L.) for the mixing angle. Pure neutrino decay and quantum decoherence hypotheses are excluded at 7 and 9 standard deviations, respectively.