Lepton flavour universality violation from composite muons

Abstract

We describe a possibility to explain the $2.6\sigma$ deviation from lepton flavour universality observed by the LHCb collaboration in $B^{+}\to K^{+}{\ell }^{+}{\ell }^{-}$ decays in the context of minimal composite Higgs models. We find that a sizable degree of compositeness of partially composite muons can lead to a good agreement with the experimental data. Our construction predicts a new physics contribution to $B_s$-${\bar{B}}_s$ mixing. Additionally, it accounts for the deficit in the invisible $Z$ width measured at LEP.

Comments: 8 pages, 3 figures. To be published in the proceedings of the European Physical Society Conference on High Energy Physics (EPS-HEP), 22-29 July 2015, Vienna, Austria