Test of lepton universality in beauty-quark decays

Authors
Aaij, R 
Beteta, CA 
Ackernley, T 
Adeva, B 
Adinolfi, M 

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Abstract

The Standard Model of particle physics currently provides our best description of fundamental particles and their interactions. The theory predicts that the different charged leptons, the electron, muon and tau, have identical electroweak interaction strengths. Previous measurements have shown a wide range of particle decays are consistent with this principle of lepton universality. This article presents evidence for the breaking of lepton universality in beauty-quark decays, with a significance of 3.1 standard deviations, based on proton-proton collision data collected with the LHCb detector at CERN's Large Hadron Collider. The measurements are of processes in which a beauty meson transforms into a strange meson with the emission of either an electron and a positron, or a muon and an antimuon. If confirmed by future measurements, this violation of lepton universality would imply physics beyond the Standard Model, such as a new fundamental interaction between quarks and leptons.

Publication Date
2022
Online Publication Date
2022-03-15
Acceptance Date
2021-11-30
Keywords
hep-ex, hep-ex
Journal Title
Nature Physics
Journal ISSN
1745-2473
1745-2481
Volume Title
18
Publisher
Springer Science and Business Media LLC