Precise Measurement of the Neutrino Mixing Parameter θ₂₃ from Muon Neutrino Disappearance in an Off-axis Beam

New data from the T2K neutrino oscillation experiment produce the most precise measurement of the neutrino mixing parameter θ₂₃. Marginalizing over the values of other oscillation parameters yields sin² (θ₂₃) = 0.514 ^+0.055_-0.056 (0.511 ± 0.055), assuming normal (inverted) mass hierarchy. The best-fit mass-squared splitting for normal hierarchy is Δm²₃₂ = 2.51 ± 0.10 × 10^-3 eV²/c⁴ (inverted hierarchy: Δm²₁₃ = 2.48 ± 0.10 × 10^-3 eV²/c⁴). Adding a model of multinucleon interactions that affect neutrino energy reconstruction is found to produce only small biases in neutrino oscillation parameter extraction at current levels of statistical uncertainty.

• arXiv preprint: https://arxiv.org/abs/1403.1532
• Reference: Phys. Rev. Lett. 112, 181801 (2014)
• DOI: https://doi.org/10.1103/PhysRevLett.112.181801