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Study of the semileptonic decay $Λ \to p ℓ {\bar{ν}}_{ℓ}$ in QCD

M. Ahmadi ^1,*, Z. Rajabi Najjar^1,†, and K. Azizi ^1,2,‡

¹Department of Physics, University of Tehran, North Karegar Avenue, Tehran 14395-547, Iran
²Department of Physics, Dogus University, Dudullu-Ümraniye, 34775 Istanbul, Türkiye

^*Contact author: masoumehahmadi@ut.ac.ir
^†Contact author: rajabinajar8361@ut.ac.ir
^‡Contact author: kazem.azizi@ut.ac.ir

Phys. Rev. D 112, 094035 – Published 19 November, 2025

DOI: https://doi.org/10.1103/wdt2-stt2

Abstract

We conduct a comprehensive study of the semileptonic decay process $Λ \to p ℓ {\bar{ν}}_{ℓ}$ , focusing on the determination of all six vector and axial-vector form factors that govern the low-energy hadronic matrix elements of the underlying theory. These invariant form factors constitute the essential inputs for describing the decay, and their dependence on the momentum transfer $q^{2}$ is analyzed across the entire physical kinematic region. To parametrize the $q^{2}$ dependence, we adopt both the $z$ -expansion formalism and a polynomial fitting approach. Utilizing these parametrizations, we compute the exclusive decay widths for both the electron and muon channels and subsequently extract the corresponding branching ratios. Furthermore, we evaluate the ratio of decay widths between the muon and electron channels defined as $R^{μ e} \equiv \frac{Γ (Λ \to p μ {\bar{ν}}_{μ})}{Γ (Λ \to p e {\bar{ν}}_{e})}$ obtaining $R^{μ e} = 0.19 6_{- 0.012}^{+ 0.009}$ from the polynomial fit and $R^{μ e} = 0.17 4_{- 0.005}^{+ 0.002}$ from the $z$ expansion. While both ratios are compatible with previously reported values in the literature, the result from the $z$ expansion exhibits particularly strong agreement with the averages reported by the Particle Data Group.

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References (54)

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Phys. Rev. D 112, 094035– Published 19 November, 2025

Vol. 112, Iss. 9 — 1 November 2025

Received 27 September 2025
Accepted 28 October 2025

DOI: https://doi.org/10.1103/wdt2-stt2

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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Study of the semileptonic decay $Λ \to p ℓ {\bar{ν}}_{ℓ}$ in QCD

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Study of the semileptonic decay Λ→pℓν¯ℓ in QCD

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Study of the semileptonic decay $Λ \to p ℓ {\bar{ν}}_{ℓ}$ in QCD