Search for FCNC Single Top-Quark Production at $\sqrt{s}=7$ TeV With the ATLAS Detector
Bibliographic record
Abstract
A search for the production of single top-quarks via flavour-changing neutral-currents is presented.Data collected with the ATLAS detector at a centre-of-mass energy of √ s = 7 TeV, corresponding to an integrated luminosity of 2.05 fb -1 , are used.Candidate events with a semileptonic top-quark decay signature are classified as signal or background-like events by using several kinematic variables as input to a neural network.No signal is observed in the neural network output distribution and a Bayesian upper limit is placed on the production cross-section.The observed upper limit at 95% confidence level on the cross-section multiplied by the t → Wb branching fraction is measured to be σ qg→t ×B(t → Wb) < 3.9 pb.This upper limit is converted using a model-independent approach into upper limits on the coupling strengths κ ugt /Λ < 6.9 • 10 -3 TeV -1 and κ cgt /Λ < 1.6 • 10 -2 TeV -1 , where Λ is the new physics scale, and on the branching fractions B(t → ug) < 5.7 • 10 -5 and B(t → cg) < 2.7 • 10 -4 .
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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 | 0.002 |
| Science and technology studies | 0.001 | 0.000 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.001 | 0.000 |
| Research integrity | 0.001 | 0.000 |
| Insufficient payload (model declined to judge) | 0.006 | 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".