Joint explanation of the <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>π</mml:mi> <mml:mi>K</mml:mi> </mml:math> puzzle and the <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>K</mml:mi> <mml:mi>ν</mml:mi> <mml:mover accent="true"> <mml:mi>ν</mml:mi> <mml:mo stretchy="false">¯</mml:mo> </mml:mover> </mml:math> excess
Bibliographic record
Abstract
In light of the recent branching fraction measurement of the B + → K + ν ν ¯ decay by Belle II and its poor agreement with the Standard Model expectation, we analyze the effects of an axionlike particle (ALP) in B meson decays. We assume a long-lived ALP with a mass of the order of the pion mass that decays to two photons. We focus on a scenario where the ALP decay length is of the order of meters such that the ALP has a non-negligible probability to decay outside the detector volume of Belle II, mimicking the B + → K + ν ν ¯ signal. Remarkably, such an arrangement is also relevant for the long-standing B → π K puzzle by noting that the measured B 0 → π 0 K 0 and B + → π 0 K + decays could have a B 0 → a K 0 and B + → a K + component, respectively. We also argue based on our results that the required ALP-photon effective coupling belongs to a region of parameter space that can be extensively probed in future beam dump experiments like SHiP.
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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 | 0.003 | 0.008 |
| Meta-epidemiology (narrow) | 0.003 | 0.001 |
| Meta-epidemiology (broad) | 0.001 | 0.002 |
| Bibliometrics | 0.002 | 0.003 |
| Science and technology studies | 0.002 | 0.001 |
| Scholarly communication | 0.006 | 0.005 |
| Open science | 0.004 | 0.003 |
| Research integrity | 0.004 | 0.004 |
| Insufficient payload (model declined to judge) | 0.589 | 0.453 |
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".