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Investigation of $Λ_{b} \to Λ_{c} ℓ^{-} \bar{ν_{ℓ}}$ decays in the perturbative QCD approach

Ying Li ^1,*, Jie Chen¹, Ya-Xin Wang², and Zhi-Tian Zou ^1,†

¹Department of Physics, Yantai University, Yantai 264005, China
²Institute of Particle Physics and Key Laboratory of Quark and Lepton Physics (MOE), Central China Normal University, Wuhan, Hubei 430079, China

^*Contact author: liying@ytu.edu.cn
^†Contact author: zouzt@ytu.edu.cn

Phys. Rev. D 113, 013003 – Published 20 January, 2026

DOI: https://doi.org/10.1103/8ztx-56ys

Abstract

We investigate the semileptonic decays $Λ_{b} \to Λ_{c} ℓ^{-} {\bar{ν}}_{ℓ}$ (with $ℓ = e$ , $μ$ , $τ$ ) within the framework of perturbative QCD. The six independent $Λ_{b} \to Λ_{c}$ transition form factors are first calculated in the low- $q^{2}$ region using the $k_{T}$ factorization approach. These are then extrapolated to the full physical $q^{2}$ range via the model-independent $z$ expansion, incorporating recent lattice QCD results at high $q^{2}$ . Based on the obtained form factors, we compute the branching fractions of $Λ_{b} \to Λ_{c} ℓ^{-} {\bar{ν}}_{ℓ}$ decays. Our prediction for the lepton flavor universality ratio, $R_{Λ_{c}} = 0.2 9_{- 0.11}^{+ 0.12}$ , is slightly larger than the latest experimental measurement. In addition, we analyze several angular observables, including forward-backward asymmetries, lepton-side convexity parameters, and polarization asymmetries. These results offer valuable theoretical input for current and future experimental investigations of semileptonic heavy-to-heavy baryon transitions.

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Phys. Rev. D 113, 013003– Published 20 January, 2026

Vol. 113, Iss. 1 — 1 January 2026

Received 16 September 2025
Accepted 2 January 2026

DOI: https://doi.org/10.1103/8ztx-56ys

Published by the American Physical Society under the terms of the Creative Commons Attribution 4.0 International license. Further distribution of this work must maintain attribution to the author(s) and the published article’s title, journal citation, and DOI. Funded by SCOAP³.

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Investigation of $Λ_{b} \to Λ_{c} ℓ^{-} \bar{ν_{ℓ}}$ decays in the perturbative QCD approach

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Investigation of Λb→Λcℓ−νℓ¯ decays in the perturbative QCD approach

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References (57)

Investigation of $Λ_{b} \to Λ_{c} ℓ^{-} \bar{ν_{ℓ}}$ decays in the perturbative QCD approach