SCET sum rules for Λ_b → Λℓ⁺ℓ^-, Λγ decays

2025/06/26 by L. Lu, Lu, Long-Shun, Cai-Dian Lü +5 · 1 citation
Physics and Astronomy · #FOS: Physical sciences #High Energy Physics - Phenomenology (hep-ph) #High-Energy Particle Collisions Research #Particle physics theoretical and experimental studies #Quantum Chromodynamics and Particle Interactions

paper · pdf · doi:10.48550/arxiv.2506.21419

openalex publication_date 2025/06/26 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28

Abstract

We construct light-cone sum rules for various types of effective form factors in the Λ_b → Λℓ⁺ℓ^- and Λ_b → Λγ decays by analyzing vacuum-to-Λ_b (or γ^∗-to-Λ_b) correlation functions with the light Λ-baryon interpolating current. These form factors, defined via hadronic matrix elements within soft-collinear effective theory (SCET), enter the next-to-leading-power QCD factorization formulas for large-recoil transitions. Implementing the perturbative matching from SCET_I to heavy quark effective theory, we determine the hard-collinear functions at next-to-leading-order accuracy. Based on light-cone sum rule predictions for the Λ_b → Λ form factors, we compute the q²-dependent differential branching fraction, forward-backward asymmetry and dilepton longitudinal polarization fraction for Λ_b → Λℓ⁺ℓ^- decay, as well as the branching fraction for Λ_b → Λγ decay.

Citations

• Radiative tail of the three-particle light-cone distribution amplitudes for the Λ_b baryon in HQET
• Non-factorisable Contributions of Strong-Penguin Operators in Λ_b → Λℓ⁺ℓ^- Decays
• A guide to the QCD light-cone sum rule for b-quark decays
• Status of next-generation Λ_b → p, Λ, Λ_c form-factor calculations
• Review of Particle Physics

Cited by

• Semileptonic neutral current decays of Ξ_b with dileptons or dineutrinos in the final state

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