Measurement of the top quark forward-backward production asymmetry and its dependence on event kinematic properties
Bibliographic record
Abstract
We present new measurements of the inclusive forward-backward $t\overline{t}$ production asymmetry, ${A}_{\mathrm{FB}}$, and its dependence on several properties of the $t\overline{t}$ system. The measurements are performed with the full Tevatron data set recorded with the CDF II detector during $p\overline{p}$ collisions at $\sqrt{s}=1.96\text{ }\text{ }\mathrm{TeV}$, corresponding to an integrated luminosity of $9.4\text{ }\text{ }{\mathrm{fb}}^{\ensuremath{-}1}$. We measure the asymmetry using the rapidity difference $\ensuremath{\Delta}y={y}_{t}\ensuremath{-}{y}_{\overline{t}}$. Parton-level results are derived, yielding an inclusive asymmetry of $0.164\ifmmode\pm\else\textpm\fi{}0.047(\mathrm{stat}+\mathrm{syst})$. We establish an approximately linear dependence of ${A}_{\mathrm{FB}}$ on the top-quark pair mass ${M}_{t\overline{t}}$ and the rapidity difference $|\ensuremath{\Delta}y|$ at detector and parton levels. Assuming the standard model, the probabilities to observe the measured values or larger for the detector-level dependencies are $7.4\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}3}$ and $2.2\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}3}$ for ${M}_{t\overline{t}}$ and $|\ensuremath{\Delta}y|$ respectively. Lastly, we study the dependence of the asymmetry on the transverse momentum of the $t\overline{t}$ system at the detector level. These results are consistent with previous lower-precision measurements and provide additional quantification of the functional dependencies of the asymmetry.
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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 | 0.000 |
| Bibliometrics | 0.001 | 0.001 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.001 | 0.001 |
| Open science | 0.000 | 0.001 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.002 | 0.000 |
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".