# Observation of the decay $B_c^+ \rightarrow J/\psi K^+ K^- \pi^+$

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## Abstract

The decay $B_c\rightarrow J/\psi K^+ K^- \pi^+$ is observed for the first time, using proton-proton collisions collected with the LHCb detector corresponding to an integrated luminosity of 3fb$^{-1}$. A signal yield of $78\pm14$ decays is reported with a significance of 6.2 standard deviations. The ratio of the branching fraction of $\B_c \rightarrow J/\psi K^+ K^- \pi^+$ decays to that of $B_c \rightarrow J/\psi \pi^+$ decays is measured to be $0.53\pm 0.10\pm0.05$, where the first uncertainty is statistical and the second is systematic.

## Figures and captions

 Mass distribution for selected (a) $B _ c ^+ \rightarrow { J \mskip -3mu/\mskip -2mu\psi \mskip 2mu} K ^+ K ^- \pi ^+$ and (b) $B _ c ^+ \rightarrow { J \mskip -3mu/\mskip -2mu\psi \mskip 2mu} \pi ^+$ candidates. The result of the fit described in the text is superimposed (solid line) together with the background component (dashed line). Fig_1.pdf [106 KiB] HiDef png [164 KiB] Thumbnail [45 KiB] *.C file tex code Background-subtracted invariant mass distributions for (a) $K ^- \pi ^+$, (b) $K ^+ K ^-$, (c) $K ^+ K ^- \pi ^+$, (d) ${ J \mskip -3mu/\mskip -2mu\psi \mskip 2mu} K ^+ K ^-$, (e) ${ J \mskip -3mu/\mskip -2mu\psi \mskip 2mu} K ^- \pi ^+$ and (f) ${ J \mskip -3mu/\mskip -2mu\psi \mskip 2mu} K ^+$ in $B _ c ^+ \rightarrow { J \mskip -3mu/\mskip -2mu\psi \mskip 2mu} K ^+ K ^- \pi ^+$ decay. The (red) full line in the $K ^- \pi ^+$ mass distribution (a) is composed of a resonant $\overline{ K }^{*0}$ contribution and a non-resonant component indicated by the dashed line. The (blue) full line in (b)--(f) shows the predictions of the model [20] used in the simulation. The regions $\pm 18 {\mathrm{\,MeV\!/}c^2}$ around the $D ^+_ s$ mass and $\pm 51 {\mathrm{\,MeV\!/}c^2}$ around the $B ^0_ s$ mass are excluded from the analysis and are indicated by the shaded areas on (c) and (d), respectively. Fig_2.pdf [183 KiB] HiDef png [483 KiB] Thumbnail [119 KiB] *.C file tex code Animated gif made out of all figures. PAPER-2013-047.gif Thumbnail

## Tables and captions

 Parameters of the signal function of the fit to the ${ J \mskip -3mu/\mskip -2mu\psi \mskip 2mu} K ^+ K ^- \pi ^+$ mass distribution. Uncertainties are statistical only. Table_1.pdf [63 KiB] HiDef png [44 KiB] Thumbnail [7 KiB] tex code Relative systematic uncertainties for the ratio of branching fractions of $B _ c ^+ \rightarrow { J \mskip -3mu/\mskip -2mu\psi \mskip 2mu} K ^+ K ^- \pi ^+$ and $B _ c ^+ \rightarrow { J \mskip -3mu/\mskip -2mu\psi \mskip 2mu} \pi ^+$. The total uncertainty is the quadratic sum of the individual components. Table_2.pdf [39 KiB] HiDef png [77 KiB] Thumbnail [11 KiB] tex code

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