A global analysis of b→ sℓℓ data in heavy and light Z^′ models

We perform a model-independent global fit to all b→ sℓℓ data in the light of recent measurements of the lepton flavour universality violating (LFUV) observables RKS0, RK∗+, and the updated observables in Bs→ ϕμ+μ- decay, by the LHCb collaboration. Assuming NP only in the muon sector, we find that the 1D NP scenarios C9NP<0 and C9NP=-C10NP continue to be the most favoured ones. However, the significance of the favoured scenario C9NP=-C9′ has reduced and the updated data now marginally prefers C10NP>0 scenario. The 2D scenarios (C9NP,C10′), (C9NP,C9′) and (C9NP,C10NP), continue to be favoured by the data in the listed order. We analyse generic TeV scale Z′ models which can generate the 1D scenarios, C9NP<0 and C9NP=-C10NP as well as 2D scenarios (C9NP,C9′) and (C9NP,C10NP). We find that all four models provide an equally good fit to the data. We also consider a model with a 25 MeV Z′ that couples to muons only and has a q2 dependent b- s coupling. We study the implications of the current data on the LFUV observables Rϕ, Q4 , 5 as well as RK(∗) in the high q2. We find that the Q4 , 5 observables have a potential to discriminate between a few favored solutions, and disentangle different heavy and light Z′ scenarios.