Observation of the $B^+ \to D^{*-} K^+\pi^+$ decay

Abstract

The $B^+ \to D^{*-} K^+\pi^+$ decay potentially provides an excellent way to investigate charm meson spectroscopy. The decay is searched for in a sample of proton-proton collision data collected with the LHCb detector at center-of-mass energies of 7 and 8 TeV, corresponding to an integrated luminosity of 3  fb$^{−1}$. A clear signal is observed, and the ratio of its branching fraction to that of the$B^+ \to D^{*-} K^+\pi^+$ normalization channel is measured to be $\mathscr{B}(B^+ \to D^{*−} K^+\pi^+) / \mathscr{B}(B^+ \to D^{*−}\pi^+\pi^+) = (6.39 \pm 0.27 \pm 0.48) \times 10^{−2}$, where the first uncertainty is statistical and the second is systematic. This is the first observation of the $B^+ \to D^{∗−}K^+\pi^+$ decay