Improved measurement of muon antineutrino disappearance in MINOS

Abstract

We report an improved measurement of ν―μ disappearance over a distance of 735 km using the MINOS detectors and the Fermilab Main Injector neutrino beam in a ν―μ-enhanced configuration. From a total exposure of 2.95×1020 protons on target, of which 42% have not been previously analyzed, we make the most precise measurement of Δm―2=[2.62−0.28+0.31(stat)±0.09(/textsyst)]×10−3 eV2 and constrain the ν―μ mixing angle sin2(2θ¯)>0.75 (90% C.L.). These values are in agreement with Δm2 and sin2(2θ) measured for νμ, removing the tension reported in [P. Adamson et al. (MINOS), Phys. Rev. Lett. 107, 021801 (2011).].