# Study of $B^+_c$ decays to the $K^+K^-\pi^+$ final state and evidence for the decay $B^+_c\to\chi_{c0}\pi^+$

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## Abstract

A study of $B_c^+\to K^+K^-\pi^+$ decays is performed for the first time using data corresponding to an integrated luminosity of 3.0 $\mathrm{fb}^{-1}$ collected by the LHCb experiment in $pp$ collisions at centre-of-mass energies of $7$ and $8$ TeV. Evidence for the decay $B_c^+\to\chi_{c0}(\to K^+K^-)\pi^+$ is reported with a significance of 4.0 standard deviations, resulting in the measurement of $\frac{\sigma(B_c^+)}{\sigma(B^+)}\times\mathcal{B}(B_c^+\to\chi_{c0}\pi^+)$ to be $(9.8^{+3.4}_{-3.0}(\mathrm{stat})\pm 0.8(\mathrm{syst}))\times 10^{-6}$. Here $\mathcal{B}$ denotes a branching fraction while $\sigma(B_c^+)$ and $\sigma(B^+)$ are the production cross-sections for $B_c^+$ and $B^+$ mesons. An indication of $\bar b c$ weak annihilation is found for the region $m(K^-\pi^+)<1.834\mathrm{ Ge V /}c^2$, with a significance of 2.4 standard deviations.

## Figures and captions

 Fit to the $K ^+ K ^- \pi ^+$ invariant mass for the $B ^+$ candidates, with $1.8340.18$, for $m( K ^- \pi ^+ )<1.834 {\mathrm{ Ge V /}c^2}$, including the vetoes in $m( K ^+ K ^- )$ (see text). Apart from the signal type, which is given by $B _ c ^+ \rightarrow K ^+ K ^- \pi ^+$, the contributions are indicated according to the same scheme as in Fig. 1. Fig2.pdf [25 KiB] HiDef png [426 KiB] Thumbnail [375 KiB] *.C file Distribution of events for the signal region $6.20.12$ and (right) $\mathcal{O}_{\mathrm{BDT}}>0.18$. The vertical red dashed lines represent a band of width $\pm60 {\mathrm{ Me V /}c^2}$ around the $\chi _{ c 0}$ mass. The horizontal blue dot-dashed line indicates the upper bound of the annihilation region at $m( K ^- \pi ^+ )=1.834 {\mathrm{ Ge V /}c^2}$, representing 17% of the available phase space area. Fig3a.pdf [24 KiB] HiDef png [174 KiB] Thumbnail [190 KiB] *.C file Fig3b.pdf [15 KiB] HiDef png [127 KiB] Thumbnail [138 KiB] *.C file Fit projections to the (left) $K ^+ K ^- \pi ^+$ and (right) $K ^+ K ^-$ invariant masses, in the bins of BDT output (top) $0.04<\mathcal{O}_{\mathrm{BDT}}<0.12$, (middle) $0.12<\mathcal{O}_{\mathrm{BDT}}<0.18$ and (bottom) $\mathcal{O}_{\mathrm{BDT}}>0.18$, for the extraction of the $B _ c ^+ \rightarrow \chi _{ c 0} (\rightarrow K ^+ K ^- )\pi ^+$ signal. The contributions from the $B _ c ^+ \rightarrow \chi _{ c 0} (\rightarrow K ^+ K ^- )\pi ^+$ signal, combinatorial background (Comb.), possible pollution from the annihilation region $B _ c ^+ \rightarrow ( K ^- \pi ^+ ) K ^+$, and combinations of $\chi _{ c 0} \rightarrow K ^+ K ^-$ with a random track $X$ are shown. Fig4a.pdf [25 KiB] HiDef png [477 KiB] Thumbnail [402 KiB] *.C file Fig4b.pdf [24 KiB] HiDef png [431 KiB] Thumbnail [358 KiB] *.C file Animated gif made out of all figures. PAPER-2016-022.gif Thumbnail

## Tables and captions

 Relative systematic uncertainties (in %) of the measurements of $R_{\mathrm{an},KK\pi}$ and $R_{\chi _{ c 0} \pi}$. Table_1.pdf [55 KiB] HiDef png [173 KiB] Thumbnail [76 KiB] tex code

## Supplementary Material [file]

 Supplementary material full pdf supple[..].pdf [308 KiB] README for supplemental material: - supplementary.pdf is the compiled version - supplement.tex is the latex source file - feyn_diags.zip contains all the Feynman diagrams of Figure 1 - all the other figures have self-explanatory names Fig2a_[..].pdf [23 KiB] HiDef png [374 KiB] Thumbnail [329 KiB] *C file Fig2b_[..].pdf [24 KiB] HiDef png [414 KiB] Thumbnail [366 KiB] *C file Fig3a_[..].pdf [14 KiB] HiDef png [140 KiB] Thumbnail [127 KiB] *C file Fig3b_[..].pdf [14 KiB] HiDef png [135 KiB] Thumbnail [119 KiB] *C file Fig4a_[..].pdf [14 KiB] HiDef png [123 KiB] Thumbnail [119 KiB] *C file Fig4b_[..].pdf [14 KiB] HiDef png [114 KiB] Thumbnail [101 KiB] *C file

Created on 17 August 2019.Citation count from INSPIRE on 23 August 2019.