LHCb anomaly in B→K^*μ⁺μ^- optimised observables and potential of Z' model

Abstract: Over the last few years LHCb found some discrepancies in b→sl⁺l^- FCNC transitions, including anomalies in the angular observables of B→K^*μ⁺μ^-, particularly in P₅', in the low dimuon mass region. Recently, these anomalies have been confirmed by Belle, CMS and ATLAS. As direct evidence of physics beyond the Standard Model is absent so far, these anomalies are being interpreted as indirect hints of new physics. In this context, we study the implications of the family non-universal Z' model for the angular observables P_1,2,3, P_4,5,6' and newly proposed lepton flavor universality violation observables, Q_4,5, in the B→K^*(→Kπ)μ⁺μ^- decay channel in the low dimuon mass region. To see the variation in the values of these observables from their Standard Model values, we have chosen different scenarios for the Z' model. It is found that these angular observables are sensitive to the values of the parameters of the Z' model. We have also found that with the present parametric space of the Z' model, the P₅'-anomaly could be accommodated. However, more statistics on the anomalies in the angular observables are helpful to reveal the status of the considered model and, in general, the nature of new physics.