First observation of the decay $B_{c}^{+}\to J/\psi K^+$

Information

LHCb-PAPER-2013-021
CERN-PH-EP-2013-106
arXiv:1306.6723 [PDF]

(Submitted on 28 Jun 2013)
JHEP 09 (2013) 75
Inspire 1240498

Tools

Abstract

The decay $B_c^+\to J/\psi K^+$ is observed for the first time using a data sample, corresponding to an integrated luminosity of 1.0 ${ fb}^{-1}$, collected by the LHCb experiment in $pp$ collisions at a centre-of-mass energy of $7\mathrm{ Te V}$. A yield of $46\pm12$ events is reported, with a significance of 5.0 standard deviations. The ratio of the branching fraction of $B_c^+\to J/\psi K^+$ to that of $B_c^+\to J/\psi\pi^+$ is measured to be $0.069\pm0.019\pm0.005$, where the first uncertainty is statistical and the second is systematic.

Figures and captions

Diagram for a $ B _ c ^+ \rightarrow { J \mskip -3mu/\mskip -2mu\psi \mskip 2mu} \pi ^+ ( K ^+ )$ decay.	Fig1.pdf [14 KiB] HiDef png [36 KiB] Thumbnail [70 KiB] *.C file
Mass distributions of $ B _ c ^+$ candidates in four $\mathrm{DLL}_{ K \pi }$ bins and the superimposed fit results. The solid shaded area (red) represents the $ B _ c ^+ \rightarrow { J \mskip -3mu/\mskip -2mu\psi \mskip 2mu} K ^+ $ signal and the hatched area (blue) the $ B _ c ^+ \rightarrow { J \mskip -3mu/\mskip -2mu\psi \mskip 2mu} \pi ^+ $ signal. The dot-dashed line (blue) indicates the partially reconstructed background and the dotted (red) the combinatorial background. The solid line (black) represents the sum of the above components and the points with error bars (black) show the data. The labels $(a)$, $(b)$, $(c)$ and $(d)$ correspond to $\mathrm{DLL}_{ K \pi } <-5$, $-5<\mathrm{DLL}_{ K \pi } <0$, $0<\mathrm{DLL}_{ K \pi } <5$ and $\mathrm{DLL}_{ K \pi } >5$ for the bachelor track, respectively.	Fig2a.pdf [21 KiB] HiDef png [500 KiB] Thumbnail [345 KiB] *.C file
	Fig2b.pdf [20 KiB] HiDef png [341 KiB] Thumbnail [253 KiB] *.C file
	Fig2c.pdf [20 KiB] HiDef png [320 KiB] Thumbnail [246 KiB] *.C file
	Fig2d.pdf [19 KiB] HiDef png [214 KiB] Thumbnail [214 KiB] *.C file
Animated gif made out of all figures.	PAPER-2013-021.gif Thumbnail