  The current world averages of the ratios $R_{D^{(*)}}$ are about $4\sigma$
away from their Standard Model prediction. These measurements indicate towards
the violation of lepton flavor universality in $b\rightarrow c\,l\,\bar{\nu}$
decay. The different new physics operators, which can explain the $R_{D^{(*)}}$
measurements, have been identified previously. We show that a simultaneous
measurement of the polarization fractions of $\tau$ and $D^*$ and the angular
asymmetries $A_{FB}$ and $A_{LT}$ in $B\rightarrow D^*\tau\bar{\nu}$ decay can
distinguish all the new physics amplitudes and hence uniquely identify the
Lorentz structure of new physics.
