Nonleptonic B decays into a charmed tensor meson

In the framework of the factorization and the heavy quark effective theory, $B\to D_2^*\pi$ modes are analyzed. We adopt the result from the QCD sum rule calculation for the hadronic matrix elements at leading order of $\Lambda_{\rm QCD}/m_Q$ and $\alpha_s$. The QCD sum rule results are well compatible with the current data, with the prediction on the branching ratios $\calB(\Bbar^0\to D_2^{*+}\pi^-)=8.94\times 10^{-4}$ and $\calB(B^-\to D_2^{*0}\pi^-)=9.53\times 10^{-4}$ for $N_C^{\rm eff}=2$. We give constraints on the interception $\tau(1)$ and the slope parameter $\rho^2$ of the leading Isgur-Wise function from the experimental bounds. It is argued that the observation of nonzero $\calB(\Bbar^0\to D_2^{*0}\pi^0)$ directly measures the nonfactorizable effets.