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

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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.

Figures and captions

Leading diagram for $ B ^+ \rightarrow D ^{*-} K ^+ \pi ^+ $ and $ D ^{*-} \pi ^+ \pi ^+ $ decays, where the $ D ^{*-} \pi ^+ $ system is produced through the decay of an excited charm state denoted $\overline{ D }{} {}^{**0}$.

BToDhh.pdf [34 KiB]
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BToDhh.pdf

Fits to $ B $ candidate mass distributions for (left) $ D ^{*-} K ^+ \pi ^+ $ and (right) $ D ^{*-} \pi ^+ \pi ^+ $ samples with (top) linear and (bottom) logarithmic $y$-axis scales. The individual components are (solid blue) total fit function, (dashed green) signal shape, (long-dashed violet) combinatorial background, (dot dashed red) partially reconstructed background and (double-dot dashed orange) $ D ^{*-} \pi ^+ \pi ^+ $ to $ D ^{*-} K ^+ \pi ^+ $ cross-feed.

DstKpi[..].pdf [34 KiB]
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DstKpi_SigFit.pdf
Dstpip[..].pdf [34 KiB]
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Dstpipi_SigFit.pdf
DstKpi[..].pdf [32 KiB]
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DstKpi_SigFit_Log.pdf
Dstpip[..].pdf [32 KiB]
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Dstpipi_SigFit_Log.pdf

Background-subtracted [38] and efficiency-corrected $m( D ^{*-} \pi ^+ )$ distribution from $ B ^+ \rightarrow D ^{*-} K ^+ \pi ^+ $ decays. The grey dashed line illustrates a phase-space distribution, normalised to the same number of weighted candidates.

DstKpi[..].pdf [19 KiB]
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DstKpi_1D_SW_Eff.pdf

Animated gif made out of all figures.

PAPER-2017-006.gif
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thumbnail_PAPER-2017-006.gif

Tables and captions

Systematic uncertainties on the ratio of branching fractions.

Table_1.pdf [24 KiB]
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tex code
Table_1.pdf

Created on 09 December 2018.Citation count from INSPIRE on 18 December 2018.