Results: Oscillations

Improved constraints on neutrino mixing from the T2K experiment with 3.13E21 protons on target

The T2K experiment reports updated measurements of neutrino and antineutrino oscillations using both appearance and disappearance channels.  This result comes from an exposure of 14.9 (16.4) × 10²⁰ protons on target in neutrino (antineutrino) mode.  For fits including a constraint on sin²θ₁₃ from reactor data and assuming normal mass ordering, T2K measures sin²θ₂₃ = 0.53^+0.03_-0.04 and Δ m²₂₃ = (2.45 ± 0.07) × 10^-3 eV²c^-4.

The Bayesian analyses show a weak preference for normal mass ordering (89% posterior probability) and the upper sin²θ₂₃ octant (80% posterior probability), with a uniform prior probability assumed in both cases. The T2K data exclude CP conservation in neutrino oscillations at the 2σ level.

Data release

Data release for the “Constraint on the matter–antimatter symmetry-violating phase in neutrino oscillations” paper

This is the data release to accompany the results of T2K’s neutrino oscillation analysis using neutrino and antineutrino data collected between 2010 and 2018, as reported in the T2K collaboration’s April 16th 2020 article in Nature.

The information shared is the value of minus two times the log of the marginal likelihood (described in the methods section of the Nature article) as a function of several of the neutrino oscillation parameters. This is referred to as the “χ2”. We also give δχ2 distributions, which are the difference in the χ2 value between the minimum χ2 and the χ2 at the other points in oscillation parameter space. Additionally, 68% and 90% confidence level contours are included in one of the two file formats detailed below. All distributions and contours have nth and ith versions which give the information for the normal and inverted neutrino mass orderings respectively.

Nature publication is available from:  https://www.nature.com/articles/s41586-020-2177-0#citeas

T2K neutrino oscillation public data release.

Measurement of neutrino and antineutrino oscillations by the T2K experiment, including a new additional sample of electron neutrino interactions in the far detector

Measurement of Muon Antineutrino Oscillations with an Accelerator-Produced Off-Axis Beam

This data release pertains to this paper.

The tar file for this data release includes a README document in PDF format, and a ROOT file.
The ROOT file contains the best-fit points in the sin²(θ₂₃)-Δm² space, the 2D χ² surface, 68% and 90% 2D confidence level contours, and 1D χ² surfaces for both sin²(θ₂₃) and Δm².
All results are given for both normal and inverted hierarchy.
Measurement of Muon Antineutrino Oscillations with an Accelerator-Produced Off-Axis Beam

ν_μ disappearance measurement results 2014

This data release pertains to this paper.
The tar file for this data release includes a README document in PDF format, a ROOT file, and a plain text table of the analysis results. The ROOT file contains the best-fit points for sin²(θ₂₃) vs. Δm², the 2D log likelihood surface, 68% and 90% 2D Feldman-Cousins contours, and 1D profiled likelihood in. All results sin²(θ₂₃) vs. Δm² are given for both normal and inverted hierarchy. The text file contains the same information in plain text format.
T2K ν_μ disappearance results 2014

ν_μ disappearance measurement results 2013

The files in the following archive file contain the results of the ν_μ disappearance measurement reported in this paper.

This tar file contains a ROOT file with the best fit, 68% and 90% confidence regions of the ν_μ disappearance fit, and the Δχ² surface. The tar file also contains TXT files with the Δχ² surfaces. A README.pdf is also provided with detailed information about the contents of the included files:
T2K ν_μ disappearance results 2013

ν_e appearance measurement results 2012

The files in the following archive file contain the results of the ν_e appearance measurement reported in this paper.

This tar file contains ROOT files with the best fit, 68% and 90% confidence interval curves of the ν_e appearance fit and the negative log likelihood distribution. A README.pdf file is also provided with detailed information about the contents of the included files:
T2K ν_e appearance results 2012

ν_e appearance (July 2012)

sin²(2θ₁₃) = 0.094+0.053-0.040 (0.116+0.063-0.049) for δ_CP = 0, Δm²₂₃ = 2.4×10^-3 eV², θ₂₃ = π/4 and normal (inverted) hierarchy.

Data set: 3.01×10²⁰ p.o.t.

ICHEP 2012 presentation

sin²(2θ₁₃)-δ_CP contour data [ROOT file],   (Readme)

ν_μ disappearance (July 2011)

2.1×10^-3 < Δm²₂₃(eV²) < 3.1×10^-3 and sin²2θ₂₃ > 0.85 at 90% C.L.

Data set: 1.43×10²⁰ p.o.t.

PRD85,031103(2012)

arXiv:1201.1386