Constructing heavy-quark sum rule for b → c meson and baryon decays

2025/09/02 by Motoi Endo, Endo, Motoi, Syuhei Iguro +5
Physics and Astronomy · #FOS: Physical sciences #High Energy Physics - Phenomenology (hep-ph) #Particle physics theoretical and experimental studies #Quantum Chromodynamics and Particle Interactions #Quantum and Classical Electrodynamics

paper · pdf · doi:10.48550/arxiv.2509.02006

openalex publication_date 2025/09/02 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/29

Abstract

We study heavy-hadron semileptonic decays proceeding via b → c transition, such as B → D^(*)τν_τ and Λ_b → Λ_cτν_τ. In the heavy-quark limit, where the heavy-quark symmetry holds, we provide a fundamental framework for heavy-quark sum rules among these decays based on the spin decomposition picture. The relation holds directly for the squared amplitudes without requiring phase-space integration. We then apply this relation to reproduce the sum rule among B → D^(*)τν_τ and Λ_b → Λ_cτν_τ. Furthermore, we derive new sum rules for Ω_b → Ω_c^(*) transitions and those involving excited states, such as B → \D₀^*,D₁^*\ and B → \D₁,D₂^*\.

Citations

• b → c semileptonic sum rule: Current status and prospects
• Projections for Key Measurements in Heavy Flavour Physics
• Heavy quark symmetry behind b → c semileptonic sum rule
• Flavor Physics at the CEPC: a General Perspective
• Averages of b-hadron, c-hadron, and τ-lepton properties as of 2023
• On sum rules for semi-leptonic b → c and b → u decays
• Testing Lepton Flavor Universality at Future Z Factories
• Snowmass White Paper: Belle II physics reach and plans for the next decade and beyond
• Hadrons of Arbitrary Spin and Heavy Quark Symmetry

Related

• b → c semileptonic sum rule: Extension to angular observables
• b → c semileptonic sum rule: Current status and prospects
• Remarks on sum rules in the heavy quark limit of QCD
• Applications of QCD Sum Rules to Heavy Quark Physics
• Recent Developments in the Theory of Heavy-Quark Decays