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arXiv · 1503.03865

Violation of lepton flavour universality in composite Higgs models

Christoph Niehoff·Peter Stangl·David M. Straub
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Abstract

We investigate whether the $2.6σ$ deviation from lepton flavour universality in $B^+\to K^+\ell^+\ell^-$ decays recently observed at the LHCb experiment can be explained in minimal composite Higgs models. We show that a visible departure from universality is indeed possible if left-handed muons have a sizable degree of compositeness. Constraints from $Z$-pole observables are avoided by a custodial protection of the muon coupling. The deficit in the invisible $Z$ width at LEP is explained in the same region of parameters.

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Christoph Niehoff, Peter Stangl, David M. Straub. 2015-08-07. Violation of lepton flavour universality in composite Higgs models. https://doi.org/10.1016/j.physletb.2015.05.063

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