Measurement of the Λ<sub><i>b</i></sub><sup>0</sup> Lifetime in the Decay Λ<sub><i>b</i></sub><sup>0</sup> → <i>J</i>/ψΛ<sup>0</sup> with the D0 Detector
Bibliographic record
Abstract
We present measurements of the Λb0 lifetime in the exclusive decay channel Λb0 → J/ψΛ0, with J/ψ → μ+μ- and Λ0 → pπ-, the B0 lifetime in the decay Λ0 → J/ψKs0 with J/ψ → μ+μ- and Ks0 → π+π-, and the ratio of these lifetimes. The analysis is based on approximately 250 pb-1 of data recorded with the D0 detector in pp̅ collisions at √s = 1.96 TeV. The Λb0 lifetime is determined to be τ(Λb0) = 1.22-0.18+0.22(stat) ± 0.04(syst) ps, the B0 lifetime τ(B0) = 1.40-0.10+0.11(stat) ± 0.03(syst) ps, and the ratio τ(Λb0)/τ(B0) = 0.87-0.14+0.17 (stat) ± 0.03(syst). In contrast with previous measurements using semileptonic decays, this is the first determination of the Λb0 lifetime based on a fully reconstructed decay channel.
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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) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.001 | 0.001 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.000 | 0.001 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.002 | 0.001 |
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".