Precise measurement of the neutrino mixing parameter θ23from muon neutrino disappearance in an off-axis beam

T2K Collaboration

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New data from the T2K neutrino oscillation experiment produce the most precise measurement of the neutrino mixing parameter θ23. Using an off-axis neutrino beam with a peak energy of 0.6 GeV and a data set corresponding to 6.57 × 1020protons on target, T2K has fit the energy-dependent νμoscillation probability to determine oscillation parameters. The 68% confidence limit on sin223) is 0.514-0.056 +0.055(0.511 ± 0.055), assuming normal (inverted) mass hierarchy. The best-fit mass-squared splitting for normal hierarchy is Δm32 2= (2.51 × 0.10) × 10-3eV2/c4(inverted hierarchy: Δm13= (2.48 ± 0.10) × 10-3eV2/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.

Original languageEnglish
Article number181801
Number of pages8
JournalPhysical Review Letters
Issue number18
Publication statusPublished - 8 May 2014
Externally publishedYes

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