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 centre-of-mass energies of 7 and 8 TeV, corresponding to an integrated luminosity of $3~{\rm fb}^{-1}$. A clear signal is observed, and the ratio of its branching fraction to that of the $B^+ \to D^{*-}\pi^+\pi^+$ normalisation channel is measured to be \begin{equation*} \frac{\mathcal{B}(B^+ \to D^{*-}K^+\pi^+)}{\mathcal{B}(B^+ \to D^{*-}\pi^+\pi^+)} = \left( 6.39 \pm 0.27 \pm 0.48 \right) \times 10^{-2} \, , \end{equation*} where the first uncertainty is statistical and the second is systematic. This is the first observation of the $B^+ \to D^{*-}K^+\pi^+$ decay.
Highlights
The B → DðÃÞhh0 decays, where hð0Þ 1⁄4 π, K, provide an excellent way to investigate the spectroscopy of excited charm mesons
The constrained initial and final states lead to comparatively low backgrounds and excellent mass resolution, and amplitude analysis can be used to determine the quantum numbers of any intermediate resonant states through their angular distributions
Very large yields are available through inclusive production of excited charm states, but studies of such processes cannot in general result in unambiguous determinations of quantum numbers, and the sizable backgrounds tend to lead to large systematic uncertainties
Summary
The Bþ → DÃ−Kþπþ 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. An important feature is that signal decays have a narrow peak in the distribution of Δm, the difference between the DÃ− and D 0 candidate masses; imposing a requirement on Δm greatly reduces the range of possible sources of background. The analysis is based on a sample of proton-proton collision data collected with the LHCb detector at centerof-mass energies of 7 and 8 TeV, corresponding to an integrated luminosity of 3 fb−1. Online event selection is performed by a trigger, which consists of a hardware stage, based on information from the calorimeter and muon systems, followed by a software stage, in which all tracks with pT > 500 ð300Þ MeV=c are reconstructed for data collected in 2011 (2012).
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