Search for pair production of a new heavy quark that decays into a $W$ boson and a light quark in $pp$ collisions at $\sqrt{s} = 8$ TeV with the ATLAS detector
Bibliographic record
Abstract
CERN-LHC. Results from a search is presented for pair production of a new heavy quark ($Q$) that decays into a $W$ boson and a light quark ($q$) in the final state where one $W$ boson decays leptonically (to an electron or muon plus a neutrino) and the other $W$ boson decays hadronically. The analysis is performed using an integrated luminosity of 20.3 fb$^{-1}$ of $pp$ collisions at $\sqrt{s} = 8$ TeV collected by the ATLAS detector at the LHC. No evidence of $Q\bar{Q}$ production is observed. New chiral quarks with masses below 690 GeV are excluded at 95% confidence level, assuming BR$(Q\to Wq)=1$. Results are also interpreted in the context of vectorlike quark models, resulting in the limits on the mass of a vectorlike quark in the two-dimensional plane of BR$(Q\to Wq)$ versus BR$(Q\to Hq)$ The main selection requirements for this analysis were: - exactly one isolated lepton with pT(lep) > 25 GeV - missing transverse momentum ETmiss > 30 GeV - "transverse" W mass + ETmiss > 60 GeV - at least four jets with pT(jet) > 25 GeV - zero b-jets - a leptonic W candidate consisting of the lepton+ETmiss system with pT > 125 GeV - a hadronic W candidate consisting of a dijet system with pT > 200 GeV, 65 GeV < mass 100 GeV, and deltaR < 1.0 between the two jets. - two reconstructed heavy quarks (W+1jet systems) with a mass difference less than 120 GeV - At least two jets (not used for the hadronic W) with pT > 120 GeV. - At least one jet (not used for the hadronic W) with pT > 160 GeV. - Scalar sum of |pT| from hadronic W, leptonic W, and two highest pT jets not used for hadronic W must be > 1.1 TeV - Angular cuts between reconstructed objects (see details in paper).
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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 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 0.000 |
| Bibliometrics | 0.001 | 0.001 |
| Science and technology studies | 0.001 | 0.000 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.001 | 0.001 |
| Research integrity | 0.001 | 0.000 |
| Insufficient payload (model declined to judge) | 0.002 | 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".