First observation of the decays $\overline{B}^0 \to D^+ K^- \pi^+ \pi^-$ and $B^- \to D^0 K^- \pi^+ \pi^-$

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First observations of the Cabibbo suppressed decays B0bar -->D+ K- pi+ pi- and B- --> D0 K- pi+ pi- are reported using 35 pb^{-1} of data collected with the LHCb detector. Their branching fractions are measured with respect to the corresponding Cabibbo favored decays, from which we obtain B(B0bar --> D+ K- pi+ pi-)/B(B0bar --> D+ pi- pi+ pi-)=(5.9\pm1.1\pm0.5) x 10^{-2} and B(B- --> D0 K- pi+ pi-)/B(B- --> D0 pi- pi+ pi-)=(9.4\pm1.3\pm0.9) x 10^{-2}, where the uncertainties are statistical and systematic, respectively. The B- --> D0 K- pi+ pi- decay is particularly interesting, as it can be used in a similar way to B- --> D0 K- to measure the CKM phase gamma.

Figures and captions

Invariant mass distributions for (a) $\overline{ B }{} ^0 \rightarrow D^+\pi^-\pi^+\pi^-$, (b) $B^-\rightarrow D^0\pi^-\pi^+\pi^-$, (c) $\overline{ B }{} ^0 \rightarrow D^+K^-\pi^+\pi^-$ and (d) $B^-\rightarrow D^0 K^-\pi^+\pi^-$ candidates from 35 $\rm pb^{-1}$ of data for all selected candidates. Fits as described in the text are overlaid.

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Invariant masses within the $B^-\rightarrow D^0 K^-\pi^+\pi^-$ system. Shown are (a) $M(K^-\pi^+\pi^-)$ , (b) $M(D\pi^+\pi^-)-M(D)$, (c) $M$($K^-\pi^+)$, and (d) $M(\pi^+\pi^-)$ . The points with error bars correspond to the signal region, and the hatched histograms represent the scaled sideband region.

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Animated gif made out of all figures.


Tables and captions

Summary of parameters used in the CS mass fits. Values without uncertainties are fixed in the CS mode fits, and values with uncertainties are included with a Gaussian constraint with central values and widths as indicated.

Table_1.pdf [53 KiB]
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Created on 06 March 2021.