Search for a long-lived spin-0 mediator in <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mi>b</mml:mi><mml:mo stretchy="false">→</mml:mo><mml:mi>s</mml:mi></mml:math> transitions at the Belle II experiment
Bibliographic record
Abstract
Additional spin-0 particles appear in many extensions of the standard model. We search for long-lived spin-0 particles $S$ in $B$-meson decays mediated by a $b\ensuremath{\rightarrow}s$ quark transition in ${e}^{+}{e}^{\ensuremath{-}}$ collisions at the $\mathrm{\ensuremath{\Upsilon}}(4S)$ resonance at the Belle II experiment. Based on a sample corresponding to an integrated luminosity of $189\text{ }\text{ }{\mathrm{fb}}^{\ensuremath{-}1}$, we observe no evidence for signal. We set model-independent upper limits on the product of branching fractions $\mathcal{B}({B}^{0}\ensuremath{\rightarrow}{K}^{*}(892{)}^{0}(\ensuremath{\rightarrow}{K}^{+}{\ensuremath{\pi}}^{\ensuremath{-}})S)\ifmmode\times\else\texttimes\fi{}\mathcal{B}(S\ensuremath{\rightarrow}{x}^{+}{x}^{\ensuremath{-}})$ and $\mathcal{B}({B}^{+}\ensuremath{\rightarrow}{K}^{+}S)\ifmmode\times\else\texttimes\fi{}\mathcal{B}(S\ensuremath{\rightarrow}{x}^{+}{x}^{\ensuremath{-}})$, where ${x}^{+}{x}^{\ensuremath{-}}$ indicates ${e}^{+}{e}^{\ensuremath{-}},{\ensuremath{\mu}}^{+}{\ensuremath{\mu}}^{\ensuremath{-}},{\ensuremath{\pi}}^{+}{\ensuremath{\pi}}^{\ensuremath{-}}$, or ${K}^{+}{K}^{\ensuremath{-}}$, as functions of $S$ mass and lifetime at the level of ${10}^{\ensuremath{-}7}$.
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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 | 0.000 |
| 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) | 0.006 | 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".