Phenomenological analysis of the quasi-two-body $B\to D(R\to )K\pi$ decays in PQCD Approach

The quasi-two-body $B\to D(R\to )K\pi$ decays are calculated in PQCD approach based on the $k_T$ factorization by introducing the wave functions of $K\pi$ pair associated with the resonances $K^{\ast }(892)$, $K_0^{\ast }(1430)$ and $K_2^{\ast }(1430)$. The results show that most branching fractions are at the order of ${10}^{-7}$ or even smaller. However, for $B^0\to D^0(K^{\ast }\to )K\pi$ decays enhanced by the CKM element $V_{cs}$, their branching fractions are at the order of ${10}^{-6}$, which are measurable in the current ongoing experiments. Based on the narrow-width-approximation we also extract the branching fractions of the corresponding two-body $B\to D{K}^{\ast }$ decays and the results are in good agreement with previous predictions. Because these decays are only governed by the tree operators, there are no $CP$ asymmetries in these decays in the standard model.