Z′ model for b → sl(l)over-bar flavor anomalies

We study the implications of flavor-changing neutral currents (FCNC's) in a model with the SU(2)(l) x SU(2)(h) x U(1)(Y) electroweak gauge symmetry for several anomalies appearing in b -> sl (l) over bar induced B decays in LHCb data. In this model, SU(2)(l) and SU(2)(h) govern the left-handed fermions in the first two generations and the third generation, respectively. The physical Z and Z' generate the b -> s transition at tree level, leading to additional contributions to the b -> s semileptonic operators O-9,O-10. We find that although B-s-(B) over bar (s) mixing constrains the parameters severely, the model can producevalues of C-9,10(NP) in the range determined by Descotes Genon et al. (Global analysis of b -> sll anomalies, arXiv:1510.04239) for this scenario to improve the global fit of observables in decays induced by the b -> s mu(mu) over bar transition. The Z' boson in this model also generates tree-level FCNC's for the leptonic interactions that can accommodate the experimental central value of R-K = B(B -> K mu(mu) over bar)/B(B -> Ke (e) over bar) = 0.75. In this case, the model predicts sizable branching ratios for B -> Ke (tau) over bar, B -> K tau(e) over bar, and an enhancement of B -> K tau(tau) over bar with respect to its standard model value.