LHC di-lepton searches for Z^ bosons which explain measurements of b → s l⁺l⁻ transitions

Several current measurements of b→ s l⁺l⁻ processes are in tension with Standard Model predictions, whereas others (e.g. RK and RK^) are in reasonable agreement with them. We examine some recent Z^ models that fit the data as a whole appreciably better than the Standard Model, confronting the models with ATLAS resonance searches in the e⁺e⁻ and μ⁺μ⁻ channels. The models are constrained by both channels; we find that the lower limit on the Z^ mass MZ^ is 0.8-1.8 TeV at the 95$%$ confidence level, depending upon the model. We provide sensitivity estimates for the HL-LHC, which extend to more than double the current limits on MZ^.