Lepton-flavor universality limits in warped space

Eugenio Megías, Mariano Quirós, Lindber Salas

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    11 Citations (Scopus)


    © 2017 American Physical Society. We explore the limits on lepton-flavor universality (LFU) violation in theories where the hierarchy problem is solved by means of a warped extra dimension. In those theories, LFU violation, in fermion interaction with Kaluza-Klein modes of gauge bosons, is provided ab initio when different flavors of fermions are differently localized along the extra dimension. As this fact arises from the mass pattern of quarks and leptons, LFU violation is natural in this class of theories. We analyze the experimental data pointing toward LFU violation, as well as the most relevant electroweak and flavor observables, and the LFU tests in the μ/e and τ/μ sectors. We find agreement with RK(∗) and RD(∗) data at 95% C.L., provided the third-generation left-handed fermions are composite (0.14<cbL<0.28 and 0.27<cτL<0.33), and find the absolute limits RK(∗)0.79 and RD(∗)/RD(∗)SM1.13. Moreover, we predict B(B→Kνν)1.14×10-5 at 95% C.L., smaller than the present experimental upper bound but a few times larger than the Standard Model prediction.
    Original languageEnglish
    Article number075030
    JournalPhysical Review D
    Issue number7
    Publication statusPublished - 23 Oct 2017


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