Branching fraction measurement of the Λ → pμ- (v)over-barμ decay



Aaij, R, Abdelmotteleb, ASW, Beteta, C Abellan, Abudinen, F, Ackernley, T, Adefisoye, AA, Adeva, B, Adinolfi, M, Adlarson, P, Agapopoulou, C
et al (show 1180 more authors) (2026) Branching fraction measurement of the Λ → pμ- (v)over-barμ decay JOURNAL OF HIGH ENERGY PHYSICS, 2026 (4). 96-. ISSN 1126-6708, 1029-8479

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Abstract

A measurement of the branching fraction for the decay Λ→pμ−ν¯μ is presented using pp collision data collected by the LHCb experiment at a centre-of-mass energy of 13 TeV. The analysis is based on data recorded between 2016 and 2018, corresponding to an integrated luminosity of 5.4 fb−1. The result is obtained using Λ → pμ decays as a normalisation channel. The measured branching fraction is BΛ→pμ−ν¯μ=1.462±0.016±0.100±0.011×10−4, where the uncertainties are statistical, systematic, and due to the limited knowledge of the normalisation mode branching fraction, respectively. This result improves the precision of the branching fraction measurement by a factor of two compared to the previous best measurement and sets a more stringent bound on lepton flavour universality in s → u quark transitions. It is consistent with previous measurements, and the extracted lepton flavour universality test observable, Rμe=ΓΛ→pμ−ν¯μΓΛ→pe−ν¯e=0.175±0.012, agrees with the Standard Model prediction.

Item Type: Article
Uncontrolled Keywords: Branching fraction, Flavour Physics, Hadron-Hadron Scattering, Electroweak Interaction
Divisions: Faculty of Humanities & Social Sciences
Faculty of Science & Engineering
Faculty of Science & Engineering > School of Physical Sciences
Faculty of Science & Engineering > School of Physical Sciences > Physics
Faculty of Humanities & Social Sciences > School of the Arts
Faculty of Humanities & Social Sciences > School of the Arts > Architecture
Depositing User: Symplectic Admin
Date Deposited: 27 Apr 2026 08:47
Last Modified: 22 May 2026 16:55
DOI: 10.1007/JHEP04(2026)096
Open Access URL: https://link.springer.com/content/pdf/10.1007/JHEP...
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URI: https://livrepository.liverpool.ac.uk/id/eprint/3198163
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