Feruglio F, Paradisi P, Pattori A. Revisiting Lepton Flavor Universality in B Decays.
PHYSICAL REVIEW LETTERS 2017;
118:011801. [PMID:
28106409 DOI:
10.1103/physrevlett.118.011801]
[Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/22/2016] [Indexed: 06/06/2023]
Abstract
Lepton flavor universality (LFU) in B decays is revisited by considering a class of semileptonic operators defined at a scale Λ above the electroweak scale v. The importance of quantum effects, so far neglected in the literature, is emphasized. We construct the low-energy effective Lagrangian taking into account the running effects from Λ down to v through the one-loop renormalization group equations (RGEs) in the limit of exact electroweak symmetry and QED RGEs from v down to the 1 GeV scale. The most important quantum effects turn out to be the modification of the leptonic couplings of the vector boson Z and the generation of a purely leptonic effective Lagrangian. Large LFU breaking effects in Z and τ decays and visible lepton flavor violating effects in the processes τ→μℓℓ, τ→μρ, τ→μπ, and τ→μη^{(')} are induced.
Collapse