Measurement of Muon Antineutrino Oscillations with an Accelerator-Produced Off-Axis Beam
Bibliographic record
Abstract
T2K reports its first measurements of the parameters governing the disappearance of ${\overline{\ensuremath{\nu}}}_{\ensuremath{\mu}}$ in an off-axis beam due to flavor change induced by neutrino oscillations. The quasimonochromatic ${\overline{\ensuremath{\nu}}}_{\ensuremath{\mu}}$ beam, produced with a peak energy of 0.6 GeV at J-PARC, is observed at the far detector Super-Kamiokande, 295 km away, where the ${\overline{\ensuremath{\nu}}}_{\ensuremath{\mu}}$ survival probability is expected to be minimal. Using a data set corresponding to $4.01\ifmmode\times\else\texttimes\fi{}{10}^{20}$ protons on target, 34 fully contained $\ensuremath{\mu}$-like events were observed. The best-fit oscillation parameters are ${\mathrm{sin}}^{2}({\overline{\ensuremath{\theta}}}_{23})=0.45$ and $|\mathrm{\ensuremath{\Delta}}{\overline{m}}_{32}^{2}|=2.51\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}3}\text{ }\text{ }{\mathrm{eV}}^{2}$ with 68% confidence intervals of $0.38--0.64$ and $2.26--2.80\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}3}\text{ }\text{ }{\mathrm{eV}}^{2}$, respectively. These results are in agreement with existing antineutrino parameter measurements and also with the ${\ensuremath{\nu}}_{\ensuremath{\mu}}$ disappearance parameters measured by T2K.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.001 | 0.001 |
| Meta-epidemiology (narrow) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.001 | 0.001 |
| Science and technology studies | 0.001 | 0.000 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.001 | 0.000 |
| Research integrity | 0.001 | 0.001 |
| Insufficient payload (model declined to judge) | 0.002 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".