Eur. Phys. J. C (2025) 85: 351
https://doi.org/10.1140/epjc/s10052-025-14033-z

Regular Article - Theoretical Physics

Transition form factors of the ${\mathrm{\Lambda }}_b\to \mathrm{\Lambda }(1520)$ in QCD light-cone sum rules

¹ Frontiers Science Center for Rare Isotopes, and School of Nuclear Science and Technology, Lanzhou University, 730000, Lanzhou, China
² Institute of Particle and Nuclear Physics, Henan Normal University, 453007, Xinxiang, China

^a jianghuayu@htu.edu.cn
^b yufsh@lzu.edu.cn

Received: 10 December 2024
Accepted: 1 March 2025
Published online: 27 March 2025

Abstract

In this work, we investigate the transition form factors for ${\mathrm{\Lambda }}_b\to \mathrm{\Lambda }(1520)$ within the framework of light-cone sum rules (LCSR), using the light-cone distribution amplitudes (LCDAs) of the ${\mathrm{\Lambda }}_b$-baryon. In the hadronic representation of the correlation function, we carefully select the appropriate Lorentz structures and isolate the contributions from both the $\mathrm{\Lambda }(1520)(J^P={(3/2)}^{-})$ and the $\mathrm{\Lambda }(1890)(J^P={(3/2)}^{+}),$ ensuring that the form factors for ${\mathrm{\Lambda }}_b\to \mathrm{\Lambda }(1520)$ can be calculated unambiguously. We also provide predictions for various physical observables in the decay ${\mathrm{\Lambda }}_b\to \mathrm{\Lambda }(1520)l^{+}{l}^{-},$ including the differential branching fraction, the lepton-side forward–backward asymmetry, the longitudinal polarization fraction, and the CP-averaged normalized angular observable. Our prediction for the differential branching fraction of ${\mathrm{\Lambda }}_b\to \mathrm{\Lambda }(1520){\mu }^{+}{\mu }^{-}$ is in good agreement with the LHCb measurement within the uncertainties.