Measurement of the<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:msubsup><mml:mi>Λ</mml:mi><mml:mi>b</mml:mi><mml:mn>0</mml:mn></mml:msubsup></mml:math>Lifetime in the Decay<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:msubsup><mml:mi>Λ</mml:mi><mml:mi>b</mml:mi><mml:mn>0</mml:mn></mml:msubsup><mml:mo>→</mml:mo><mml:mi>J</mml:mi><mml:mo>/</mml:mo><mml:mi>ψ</mml:mi><mml:msup><mml:mi>Λ</mml:mi><mml:mn>0</mml:mn></mml:msup></mml:math>with the D0 Detector
Bibliographic record
Abstract
We present measurements of the ${\ensuremath{\Lambda}}_{b}^{0}$ lifetime in the exclusive decay channel ${\ensuremath{\Lambda}}_{b}^{0}\ensuremath{\rightarrow}J/\ensuremath{\psi}{\ensuremath{\Lambda}}^{0}$, with $J/\ensuremath{\psi}\ensuremath{\rightarrow}{\ensuremath{\mu}}^{+}{\ensuremath{\mu}}^{\ensuremath{-}}$ and ${\ensuremath{\Lambda}}^{0}\ensuremath{\rightarrow}p{\ensuremath{\pi}}^{\ensuremath{-}}$, the ${B}^{0}$ lifetime in the decay ${B}^{0}\ensuremath{\rightarrow}J/\ensuremath{\psi}{K}_{S}^{0}$ with $J/\ensuremath{\psi}\ensuremath{\rightarrow}{\ensuremath{\mu}}^{+}{\ensuremath{\mu}}^{\ensuremath{-}}$ and ${K}_{S}^{0}\ensuremath{\rightarrow}{\ensuremath{\pi}}^{+}{\ensuremath{\pi}}^{\ensuremath{-}}$, and the ratio of these lifetimes. The analysis is based on approximately $250\text{ }\text{ }{\mathrm{pb}}^{\ensuremath{-}1}$ of data recorded with the D0 detector in $p\overline{p}$ collisions at $\sqrt{s}=1.96\text{ }\text{ }\mathrm{TeV}$. The ${\ensuremath{\Lambda}}_{b}^{0}$ lifetime is determined to be $\ensuremath{\tau}({\ensuremath{\Lambda}}_{b}^{0})={1.22}_{\ensuremath{-}0.18}^{+0.22}(\mathrm{stat})\ifmmode\pm\else\textpm\fi{}0.04(\mathrm{syst})\text{ }\text{ }\mathrm{ps}$, the ${B}^{0}$ lifetime $\ensuremath{\tau}({B}^{0})={1.40}_{\ensuremath{-}0.10}^{+0.11}(\mathrm{stat})\ifmmode\pm\else\textpm\fi{}0.03(\mathrm{syst})\text{ }\text{ }\mathrm{ps}$, and the ratio $\ensuremath{\tau}({\ensuremath{\Lambda}}_{b}^{0})/\ensuremath{\tau}({B}^{0})={0.87}_{\ensuremath{-}0.14}^{+0.17}(\mathrm{stat})\ifmmode\pm\else\textpm\fi{}0.03(\mathrm{syst})$. In contrast with previous measurements using semileptonic decays, this is the first determination of the ${\ensuremath{\Lambda}}_{b}^{0}$ 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 | 0.002 |
| 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 | 0.001 |
| Open science | 0.002 | 0.001 |
| Research integrity | 0.002 | 0.002 |
| Insufficient payload (model declined to judge) | 0.035 | 0.013 |
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".