Determination of the Width of the Top Quark
Bibliographic record
Abstract
We extract the total width of the top quark, ${\ensuremath{\Gamma}}_{t}$, from the partial decay width $\ensuremath{\Gamma}(t\ensuremath{\rightarrow}Wb)$ measured using the $t$-channel cross section for single top-quark production and from the branching fraction $\mathcal{B}(t\ensuremath{\rightarrow}Wb)$ measured in $t\overline{t}$ events using up to $2.3\text{ }\text{ }{\mathrm{fb}}^{\ensuremath{-}1}$ of integrated luminosity collected by the D0 Collaboration at the Tevatron $p\overline{p}$ Collider. The result is ${\ensuremath{\Gamma}}_{t}={1.99}_{\ensuremath{-}0.55}^{+0.69}\text{ }\text{ }\mathrm{GeV}$, which translates to a top-quark lifetime of ${\ensuremath{\tau}}_{t}=({3.3}_{\ensuremath{-}0.9}^{+1.3})\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}25}\text{ }\text{ }\mathrm{s}$. Assuming a high mass fourth generation ${b}^{\ensuremath{'}}$ quark and unitarity of the four-generation quark-mixing matrix, we set the first upper limit on $|{V}_{t{b}^{\ensuremath{'}}}|<0.63$ at 95% C.L.
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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 | 0.000 | 0.001 |
| Meta-epidemiology (narrow) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.001 |
| Bibliometrics | 0.001 | 0.001 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.001 | 0.001 |
| Open science | 0.001 | 0.001 |
| Research integrity | 0.001 | 0.000 |
| Insufficient payload (model declined to judge) | 0.003 | 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".