Measurement of the branching ratio <math><mi mathvariant="normal" is="true">Γ</mi><mo stretchy="false" is="true">(</mo><msubsup is="true"><mrow is="true"><mi mathvariant="normal" is="true">Λ</mi></mrow><mrow is="true"><mi is="true">b</mi></mrow><mrow is="true"><mn is="true">0</mn></mrow></msubsup><mo stretchy="false" is="true">→</mo><mi is="true">ψ</mi><mo stretchy="false" is="true">(</mo><mn is="true">2</mn><mi is="true">S</mi><mo stretchy="false" is="true">)</mo><msup is="true"><mrow is="true"><mi mathvariant="normal" is="true">Λ</mi></mrow><mrow is="true"><mn is="true">0</mn></mrow></msup><mo stretchy="false" is="true">)</mo><mo stretchy="false" is="true">/</mo><mi mathvariant="normal" is="true">Γ</mi><mo stretchy="false" is="true">(</mo><msubsup is="true"><mrow is="true"><mi mathvariant="normal" is="true">Λ</mi></mrow><mrow is="true"><mi is="true">b</mi></mrow><mrow is="true"><mn is="true">0</mn></mrow></msubsup><mo stretchy="false" is="true">→</mo><mi is="true">J</mi><mo stretchy="false" is="true">/</mo><mi is="true">ψ</mi><msup is="true"><mrow is="true"><mi mathvariant="normal" is="true">Λ</mi></mrow><mrow is="true"><mn is="true">0</mn></mrow></msup><mo stretchy="false" is="true">)</mo></math> with the ATLAS detector
Bibliographic record
Abstract
An observation of the Λb0→ψ(2S)Λ0 decay and a comparison of its branching fraction with that of the Λb0→J/ψΛ0 decay has been made with the ATLAS detector in proton–proton collisions at s=8 TeV at the LHC using an integrated luminosity of 20.6 fb−1. The J/ψ and ψ(2S) mesons are reconstructed in their decays to a muon pair, while the Λ0→pπ− decay is exploited for the Λ0 baryon reconstruction. The Λb0 baryons are reconstructed with transverse momentum pT>10 GeV and pseudorapidity |η|<2.1 . The measured branching ratio of the Λb0→ψ(2S)Λ0 and Λb0→J/ψΛ0 decays is Γ(Λb0→ψ(2S)Λ0)/Γ(Λb0→J/ψΛ0)=0.501±0.033(stat)±0.019(syst) , lower than the expectation from the covariant quark model.
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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 | 0.001 |
| Meta-epidemiology (broad) | 0.001 | 0.001 |
| Bibliometrics | 0.001 | 0.001 |
| Science and technology studies | 0.001 | 0.001 |
| Scholarly communication | 0.002 | 0.002 |
| Open science | 0.001 | 0.001 |
| Research integrity | 0.001 | 0.002 |
| Insufficient payload (model declined to judge) | 0.077 | 0.028 |
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".