Neutrino oscillation physics potential of the T2K experiment

Abstract

The observation of the recent electron neutrino appearance in a muon neutrino beam and the high-precision measurement of the mixing angle θ13 have led to a re-evaluation of the physics potential of the T2K long-baseline neutrino oscillation experiment. Sensitivities are explored for CP violation in neutrinos, non-maximal sin22θ23, the octant of θ23, and the mass hierarchy, in addition to the measurements of δCP, sin2θ23, and Δm232, for various combinations of ν-mode and ν¯-mode data-taking. With an exposure of 7.8×1021 protons-on-target, T2K can achieve 1σ resolution of 0.050 (0.054) on sin2θ23 and 0.040 (0.045)×10−3eV2 on Δm232 for 100% (50%) neutrino beam mode running assuming sin2θ23=0.5 and Δm232=2.4×10−3eV2. T2K will have sensitivity to the CP violating phase δCP at 90% C.L. or better over a significant range. For example, if sin22θ23 is maximal (i.e.θ23=45∘) the range is−115∘<δCP<−60∘ for normal hierarchy and +50∘<δCP<+130∘ for inverted hierarchy. When T2K data is combined with data from the NO ν A experiment, the region of oscillation parameter space where there is sensitivity to observe a non-zero δCP is substantially increased compared to if each experiment is analyzed alone.