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

Several current measurements of b → s l + l − processes are in tension with Standard Model predictions, whereas others (e.g. R K and R K ⁎ ) are in reasonable agreement with them. We examine some recent Z ′ models that fit the data as a whole appreciably better than does 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 searches rule out less than one fifth of the allowed range of M Z ′ . We estimate that the HL-LHC can roughly double the current sensitivity in M Z ′ , but to cover the whole of the parameter space would take a more powerful machine, such as a 100 TeV pp collider.