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$Λ_{b} \to Λ$ form factors from light-cone sum rules with $Λ$ -baryon distribution amplitudes

¹Université Claude Bernard Lyon 1, CNRS/IN2P3, Institut de Physique des 2 Infinis de Lyon, UMR 5822, F-69622, Villeurbanne, France
²Theoretical Physics Department, CERN, CH-1211 Geneva 23, Switzerland
³Institut Universitaire de France (IUF), 75005 Paris, France

^*Contact author: nazila@cern.ch
^†Contact author: d.mishra@ip2i.in2p3.fr

Phys. Rev. D 114, 073006 – Published 27 October, 2026

DOI: https://doi.org/10.1103/4y46-ldjv

Abstract

We compute the $Λ_{b} \to Λ$ transition form factors using light-cone sum rules based on $Λ$ -baryon distribution amplitudes, including contributions up to twist 6. The analysis is performed for pseudoscalar, vector, and axial-vector $b \to s$ currents and for different choices of the $Λ_{b}$ interpolating current. A central aspect of the study is the explicit inclusion of the negative-parity $Λ_{b}^{*}$ state in the hadronic dispersion relation. Suitable linear combinations of invariant amplitudes are constructed to eliminate the $Λ_{b}^{*}$ pole contribution at the level of the sum rules. All three interpolating currents lead to numerically stable sum rules in the adopted working windows. The pseudoscalar current gives the closest agreement with the expected equation of motion and heavy quark symmetry relations at the level of the central values, while the present leading-order uncertainties do not allow a definitive discrimination among the three currents. The resulting helicity form factors are parametrized using a $z$ expansion and, for the pseudoscalar current, are combined with lattice-QCD tensor form factors to illustrate the low- $q^{2}$ differential branching fraction in $Λ_{b} \to Λ ℓ^{+} ℓ^{-}$ .

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Phys. Rev. D 114, 073006– Published 27 October, 2026

Vol. 114, Iss. 7 — 1 October 2026

Received 14 January 2026
Accepted 9 October 2026

DOI: https://doi.org/10.1103/4y46-ldjv

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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$Λ_{b} \to Λ$ form factors from light-cone sum rules with $Λ$ -baryon distribution amplitudes

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Λb→Λ form factors from light-cone sum rules with Λ-baryon distribution amplitudes

Abstract

Physics Subject Headings (PhySH)

Article Text

References (58)

$Λ_{b} \to Λ$ form factors from light-cone sum rules with $Λ$ -baryon distribution amplitudes