We report the first observation of a number of decay modes of the $B$ meson, namely $B^0\to D^{*-}(5\pi {)}^{+}$, $B^{+}\to D^{*-}(4\pi {)}^{++}$, and $B^{+}\to {\overline{D}}^{*0}(5\pi {)}^{+}$, where $(n\pi )$ implies the combination of $n$ charged pions. The analysis is based on a $140{\mathrm{f}\mathrm{b}}^{-1}$ data sample collected at the ${\rm Y}(4S)$ resonance with the Belle detector at KEKB. We measure $\mathcal{B}[B^0\to D^{*-}(5\pi {)}^{+}]=(4.72\pm 0.59\pm 0.71)\times {10}^{-3}$, $\mathcal{B}[B^{+}\to D^{*-}(4\pi {)}^{++}]=(2.56\pm 0.26\pm 0.33)\times {10}^{-3}$, and $\mathcal{B}[B^{+}\to {\overline{D}}^{*0}(5\pi {)}^{+}]=(5.67\pm 0.91\pm 0.85)\times {10}^{-3}$. We also provide improved measurements of the branching fractions for the decay modes $B^0\to D^{*-}(3\pi {)}^{+}$, $B^{+}\to {\overline{D}}^{*0}(3\pi {)}^{+}$, and $B^0\to {\overline{D}}^{*0}(4\pi {)}^0$.

• Received 1 September 2004

DOI:https://doi.org/10.1103/PhysRevD.70.111103