New physics in B →k∗τ+τ-: A model independent analysis

In this work, we consider the implications of current b→sℓ+ℓ- (ℓ=e, μ) measurements on several B→K∗τ+τ- observables under the assumption that the possible new physics can have both universal as well as nonuniversal couplings to leptons. For new physics solutions which provide a good fit to all b→sℓ+ℓ- data, we intend to identify observables with large deviations from the Standard Model (SM) predictions as well as to discriminate between various new physics solutions. For this we consider the B→K∗τ+τ- branching fraction, the K∗ longitudinal fraction fL, the tau forward-backward asymmetry AFB and the optimized observables in the Pi(′) basis. Further, we construct the τ-μ lepton-flavor differences (Qτμ) between these tau observables and their muonic counterparts in B→K∗μ+μ- decay. Moreover, we also consider lepton-flavor ratios (Rτμ) of all of these observables. We find that the current data allows for deviations ranging from 25% up to an order of magnitude from the SM value in a number of observables. For e.g., the magnitudes of QP3τμ and QP8′τμ observables can be enhanced up to an order of magnitude, a twofold enhancement in QAFBτμ is possible along with ∼50% enhancement in RK∗τμ and ∼25% in RAFBτμ. Moreover, the branching ratio of B→K∗τ+τ- can be suppressed up to 25%. A precise measurement of these observables can also discriminate between a number of new physics solutions.