Observation of $B^0 \to D^{*-} (5\pi)^+$, $B^+ \to D^{*-} (4\pi)^{++}$ and $B^+ \to \bar{D}^{*0} (5\pi)^+$

TL;DR

This paper reports the first observation of specific B meson decay modes involving multiple pions and measures their branching fractions using data from the Belle detector at KEKB, providing new insights into B meson decay processes.

Contribution

First observation and measurement of several B meson decay modes involving multiple pions, expanding understanding of B decay channels.

Findings

Measured branching fractions for new decay modes.

Improved measurements for previously known decay channels.

First observation of these specific multi-pion B decays.

Abstract

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 $B^+ \to \bar{D}^{*0} (5\pi)^+$, where $(n\pi)$ implies the combination of n charged pions. The analysis is based on a 140 fb$^{-1}$ data sample collected at the $\Upsilon(4S)$ resonance with the Belle detector at KEKB. We measure ${\cal{B}}(B^0 \to D^{*-} (5\pi)^+) = (4.72 \pm 0.59 \pm 0.71) \times 10^{-3}$, ${\cal{B}}(B^+ \to D^{*-} (4\pi)^{++} = (2.56 \pm 0.26 \pm 0.33) \times 10^{-3}$ and ${\cal{B}}(B^+ \to \bar{D}^{*0} (5\pi)^+) = (5.67 \pm 0.91 \pm 0.85) \times 10^{-3}$. We also provide improved measurements of the branching fractions for the decay modes $B^0 \to D^{*-} (3\pi)^+$, $B^+ \to \bar{D}^{*0} (3\pi)^+$ and $B^0 \to \bar{D}^{*0} (4\pi)^0$.