Observation of the decay $B_c^+ \to B_s^0 \pi^+$

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Abstract

The result of a search for the decay Bc+ -> Bs0 pi+ is presented, using the Bs0 -> Ds- pi+ and Bs0 -> J/psi Phi channels. The analysis is based on a data sample of pp collisions collected with the LHCb detector, corresponding to an integrated luminosity of 1 fb-1 taken at a center-of-mass energy of 7 TeV, and 2 fb-1 taken at 8 TeV. The decay Bc+ -> Bs0 pi+ is observed with significance in excess of five standard deviations independently in both decay channels. The measured product of the ratio of cross-sections and branching fraction is sigma(Bc+)/sigma(Bs0) x BR(Bc+ -> Bs0 pi+) = (2.37 \pm 0.31 (stat) \pm 0.11 (syst)^{+0.17}_{-0.13} (tau_Bc)) x 10^-3 in the pseudorapidity range 2 < eta(B) < 5, where the first uncertainty is statistical, the second is systematic and the third is due to the uncertainty on the Bc lifetime. This is the first observation of a B meson decaying to another B meson via the weak interaction.

Figures and captions

 Leading-order Feynman diagram of the decay $B _ c ^+ \rightarrow B ^0_ s \pi ^+$. fig1.pdf [11 KiB] HiDef png [39 KiB] Thumbnail [6 KiB] *.C file Invariant mass distributions of (a) $B ^0_ s \rightarrow D ^-_ s \pi ^+$ and (b) $B ^0_ s \rightarrow { J \mskip -3mu/\mskip -2mu\psi \mskip 2mu} \phi$ candidates. The different components are defined in the legend. Fig_2.pdf [76 KiB] HiDef png [178 KiB] Thumbnail [49 KiB] *.C file tex code $B _ c ^+$ mass fits for the combined 2011 and 2012 data sets for (a) $B _ c ^+ \rightarrow B ^0_ s (\rightarrow D ^-_ s \pi ^+ ) \pi ^+$ and (b) $B _ c ^+ \rightarrow B ^0_ s (\rightarrow { J \mskip -3mu/\mskip -2mu\psi \mskip 2mu} \phi) \pi ^+$ candidates. The different components are indicated in the legends. Fig_3.pdf [51 KiB] HiDef png [266 KiB] Thumbnail [66 KiB] *.C file tex code Animated gif made out of all figures. PAPER-2013-044.gif Thumbnail

Tables and captions

 Contributions of the various sources of (relative) systematic uncertainty on the efficiency-corrected ratio of event yields. The total systematic uncertainty is the quadratic sum of the individual contributions. The number of $B _ c ^+ \rightarrow B ^0_ s (\rightarrow D ^-_ s \pi ^+ ) \pi ^+$ candidates is large enough that the peak position and width are freely varied in the fit, and hence the corresponding uncertainty is contained in the statistical uncertainty of the signal yield. Table_1.pdf [48 KiB] HiDef png [93 KiB] Thumbnail [15 KiB] tex code

Created on 23 February 2019.Citation count from INSPIRE on 23 February 2019.