Measurement of the<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mi>W</mml:mi></mml:math>boson helicity in top quark decays using<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mn>5.4</mml:mn><mml:mtext> </mml:mtext><mml:mtext> </mml:mtext><mml:msup><mml:mi>fb</mml:mi><mml:mrow><mml:mo>−</mml:mo><mml:mn>1</mml:mn></mml:mrow></mml:msup></mml:math>of<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mi>p</mml:mi><mml:mover accent="true"><mml:mi>p</mml:mi><mml:mo>¯</mml:mo></mml:mover></mml:math>collision data
Bibliographic record
Abstract
We present a measurement of the helicity of the $W$ boson produced in top quark decays using $t\overline{t}$ decays in the $\ensuremath{\ell}+\mathrm{\text{jets}}$ and dilepton final states selected from a sample of $5.4\text{ }\text{ }{\mathrm{fb}}^{\ensuremath{-}1}$ of collisions recorded using the D0 detector at the Fermilab Tevatron $p\overline{p}$ collider. We measure the fractions of longitudinal and right-handed $W$ bosons to be ${f}_{0}=0.669\ifmmode\pm\else\textpm\fi{}0.102[\ifmmode\pm\else\textpm\fi{}0.078(\mathrm{stat}.)\ifmmode\pm\else\textpm\fi{}0.065(\mathrm{syst}.)]$ and ${f}_{+}=0.023\ifmmode\pm\else\textpm\fi{}0.053[\ifmmode\pm\else\textpm\fi{}0.041(\mathrm{stat}.)\ifmmode\pm\else\textpm\fi{}0.034(\mathrm{syst}.)]$, respectively. This result is consistent at the 98% level with the standard model. A measurement with ${f}_{0}$ fixed to the value from the standard model yields ${f}_{+}=0.010\ifmmode\pm\else\textpm\fi{}0.037[\ifmmode\pm\else\textpm\fi{}0.022(\mathrm{stat}.)\ifmmode\pm\else\textpm\fi{}0.030(\mathrm{syst}.).]$.
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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 | 0.001 | 0.000 |
| Scholarly communication | 0.001 | 0.001 |
| Open science | 0.001 | 0.001 |
| Research integrity | 0.001 | 0.001 |
| Insufficient payload (model declined to judge) | 0.023 | 0.008 |
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".