Search for short- and long-lived axion-like particles in $H\\rightarrow a a \\rightarrow 4\\gamma$ decays with the ATLAS experiment at the LHC
Bibliographic record
Abstract
A search for anomalous Higgs boson decays into two axion-like particles (ALPs) is presented, using the full Run-2 data set recorded by the ATLAS experiment. The ALPs are assumed to decay into two photons, providing sensitivity to various recently proposed models that could explain the famous $(g-2)_\\mu$ discrepancy. This analysis covers a mass range of ALPs between 100 MeV and 62 GeV, as well as ALP-photon couplings of $10^{-5}\\,\\text{TeV}^{-1}<C_{a\\gamma\\gamma}/\\Lambda<1 \\,\\text{TeV}^{-1}$, and therefore includes signatures with significantly displaced vertices and highly collinear photons. No significant excess of events above the Standard Model background is observed. Upper limits at 95\\% confidence level are placed on the branching ratio of the Higgs boson to the four photon final state, and are in the range of $ 10^{-5}$ to $3\\times 10^{-2}$, depending on the signal mass and ALP-photon coupling strength hypothesis.
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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) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.002 | 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) | 0.003 | 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".