  The confirmation of excess in $R_{D^*}$ at the LHCb is an indication of
lepton flavor non-universality. Various different new physics operators and
their coupling strengths, which provide a good fit to $R_D$, $R_{D^*}$ and
$q^2$ spectra, were identfied previously. In this work, we try to find angular
observables in $\bar{B} \to D^* \tau \bar{\nu}$ which enable us to distinguish
between these new physics operators. We find that the $D^*$ polarization
fraction $f_L(q^2)$ is a good discriminant of scalar and tensor new physics
operators. The change in $\langle f_L(q^2) \rangle$, induced by scalar and
tensor operators, is about three times larger than the expected uncertainty in
the upcoming Belle measurement.
