PhysicsarXiv
Ranked by formulaVerdict: NotableMeasurements of the branching fractions of Λ c + toΛK + π 0 and Λ c + toΛK + η decays at Belle and Belle II
We present a study of the three-body, singly Cabibbo-suppressed decays Λ c + to ΛK + π 0 and Λ c + to ΛK + η using data recorded with the Belle and Belle II detectors at the KEKB and SuperKEKB e + e - colliders.
Key numbers
- 10 standard deviations
Caveats
- Preprint; not yet peer reviewed.
VerdictWorth a reader's time today.
Abstract
We present a study of the three-body, singly Cabibbo-suppressed decays Λ_c⁺ → ΛK⁺ π⁰ and Λ_c⁺ → ΛK⁺ η using data recorded with the Belle and Belle II detectors at the KEKB and SuperKEKB e⁺ e⁻ colliders. The data samples correspond to integrated luminosities of 980 fb⁻¹ and 570 fb⁻¹, respectively. We measure their branching-fraction ratios relative to the Cabibbo-favored decay Λ_c⁺ → Λπ⁺ π⁰ as $B(Λ_c^+ \to ΛK^+ π^0)/B(Λ_c^+ \to Λπ^+ π^0)=(1.82 ± 0.07 ± 0.07)%$, with significantly improved precision compared to the previous measurement, and $B(Λ_c^+ \to ΛK^+ η)/B(Λ_c^+ \to Λπ^+ π^0)=(8.73 ± 0.35 ± 0.43)\times10^{-3}$, corresponding to the first observation of the $Λ_c^+ \to ΛK^+ η$ decay with a statistical significance exceeding 10 standard deviations. The first and second uncertainties are statistical and systematic, respectively. Using the world-average value of the branching fraction for Λ_c⁺ → Λπ⁺ π⁰, we obtain the branching fractions B(Λ_c⁺ → ΛK⁺ π⁰)=(1.29± 0.05± 0.05± 0.06)×10⁻³ and B(Λ_c⁺ → ΛK⁺ η)=(6.20± 0.25± 0.31± 0.30)×10⁻⁴, where the third uncertainty arises from the uncertainty in the world-average value of B(Λ_c⁺ → Λπ⁺ π⁰). The measured B(Λ_c⁺→ΛK⁺η) is significantly larger than predictions based on SU(3) flavor symmetry.
The editor's rubric
- Leverage3 / 5
- A method or resource many groups across the field will adopt within a year.
- Magnitude3 / 5
- Large gain: roughly 2x, or a clear new state of the art on a hard, unsaturated problem.
- Evidence4 / 5
- Strong: large scale, preregistered, independently replicated, or a well-powered randomized trial.
- Novelty3 / 5
- A genuinely new approach to an open problem.
- Trajectory2 / 5
- Some room to improve with obvious engineering.
- Stakes2 / 5
- Benefits a professional community (practitioners, clinicians, engineers).
Editor’s rationale
Heuristic triage from title and abstract text only, not a reading of the paper. Cues found: method (we propose); gains (outperforms); firsts (first); novelty (discovery); verification (sigma, error bars).
How the score was computed
Desks place stronger verdicts first, then use this score to order work within the same verdict.
- Merit
- 6.1 / 10
- Adjusted merit
- 4.9 / 10
- Attention
- 0%
- Freshness
- 93%