  We discuss possible new physics (NP) effects beyond the standard model (SM)
in the exclusive decays $\bar{B}^0 \to D^{(\ast)} \tau^- \bar{\nu}_{\tau}$.
Starting with a model-independent effective Hamiltonian including non-SM
four-Fermi operators, we show how to obtain experimental constraints on
different NP scenarios and investigate their effects on a large set of physical
observables. The $\bar{B}^0 \to D^{(\ast)}$ transition form factors are
calculated in the full kinematic $q^2$ range by employing the covariant
confined quark model developed by our group.
