Z′ models for the LHCb and g-2 muon anomalies

We revisit a class of Z′ explanations of the anomalies found by the LHCb collaboration in B decays, and show that the scenario is tightly constrained by a combination of constraints: (i) LHC searches for dimuon resonances, (ii) perturbativity of the Z′ couplings; (iii) the Bs mass difference, and (iv) electroweak precision data. Solutions are found by suppressing the Z′ coupling to electrons and to light quarks and/or by allowing for a Z′ decay width into dark matter. We also present a simplified framework where a TeV-scale Z′ gauge boson that couples to standard leptons as well as to new heavy vectorlike leptons, can simultaneously accommodate the LHCb anomalies and the muon g-2 anomaly.