The current world averages of the ratios RD(∗) are about 4σ away from their Standard Model prediction. These measurements indicate towards the violation of lepton flavor universality in b → cl ¯ν decay. The different new physics operators, which can explain the RD(*) measurements, have been identified previously. We show that a simultaneous measurement of the polarization fractions of τ and D* and the angular asymmetries AFB and ALT in B → D*τ ¯ν decay can distinguish all the new physics amplitudes and hence uniquely identify the Lorentz structure of new physics. © Springer Nature Switzerland AG 2019.