Fermiophobic Z′ model for simultaneously explaining the muon anomalies RK(*) and (g-2)μ

We discuss a simple renormalizable, gauge invariant model with a fermiophobic Z' boson: it has no couplings to the three Standard Model (SM) chiral families, but does couple to a fourth vectorlike (VL) family. The SM Higgs couples to the fourth VL lepton, leading to an enhanced contribution to the muon anomalous magnetic moment (g - 2)(mu). The latter contribution requires a nonvanishing coupling of Z' to right-handed muons, which arises within this model due to mixing effects between the SM and VL fennions, along with Z' couplings to the second generation SM lepton doublet and third generation SM quark doublet. This model can simultaneously account for the measured B-decay ratios R-K(*) and (g-2)(mu). We identify the parameter space where this explanation is consistent with existing experimental constraints coming from B-s - (B) over bar (s) mixing, neutrino trident production and collider searches. We also check that the SM Higgs coupling to the fourth VL lepton does not produce a dangerous contribution to the Higgs diphoton decay.

Automated summary

We discuss a simple renormalizable, gauge invariant model with a fermiophobic Z' boson, which can simultaneously explain the measured B-decay ratios and the muon anomalous magnetic moment.