Search for Long-Lived Particles in<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:msup><mml:mrow><mml:mi>e</mml:mi></mml:mrow><mml:mrow><mml:mo>+</mml:mo></mml:mrow></mml:msup><mml:msup><mml:mrow><mml:mi>e</mml:mi></mml:mrow><mml:mrow><mml:mo>−</mml:mo></mml:mrow></mml:msup></mml:mrow></mml:math>Collisions
Bibliographic record
Abstract
We present a search for a neutral, long-lived particle $L$ that is produced in ${e}^{+}{e}^{\ensuremath{-}}$ collisions and decays at a significant distance from the ${e}^{+}{e}^{\ensuremath{-}}$ interaction point into various flavor combinations of two oppositely charged tracks. The analysis uses an ${e}^{+}{e}^{\ensuremath{-}}$ data sample with a luminosity of $489.1\text{ }\text{ }{\mathrm{fb}}^{\ensuremath{-}1}$ collected by the BABAR detector at the $\mathrm{\ensuremath{\Upsilon}}(4S)$, $\mathrm{\ensuremath{\Upsilon}}(3S)$, and $\mathrm{\ensuremath{\Upsilon}}(2S)$ resonances and just below the $\mathrm{\ensuremath{\Upsilon}}(4S)$. Fitting the two-track mass distribution in search of a signal peak, we do not observe a significant signal, and set 90% confidence level upper limits on the product of the $L$ production cross section, branching fraction, and reconstruction efficiency for six possible two-body $L$ decay modes as a function of the $L$ mass. The efficiency is given for each final state as a function of the mass, lifetime, and transverse momentum of the candidate, allowing application of the upper limits to any production model. In addition, upper limits are provided on the branching fraction $\mathcal{B}(B\ensuremath{\rightarrow}{X}_{s}L)$, where ${X}_{s}$ is a strange hadronic system.
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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 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.001 |
| 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 | 0.000 |
| Insufficient payload (model declined to judge) | 0.010 | 0.002 |
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".