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First observation of a baryonic $B_c^+$ decay

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Abstract

A baryonic decay of the $B_c^+$ meson, $B_c^+\to J/\psi p\overline{p}\pi^+$, is observed for the first time, with a significance of $7.3$ standard deviations, in $pp$ collision data collected with the LHCb detector and corresponding to an integrated luminosity of $3.0$ fb$^{-1}$ taken at center-of-mass energies of $7$ and $8$ $\mathrm{TeV}$. With the $B_c^+\to J/\psi \pi^+$ decay as normalization channel, the ratio of branching fractions is measured to be \begin{equation*} \frac{\mathcal{B}(B_c^+\to J/\psi p\overline{p}\pi^+)}{\mathcal{B}(B_c^+\to J/\psi \pi^+)} = 0.143^{ + 0.039}_{ - 0.034} (\mathrm{stat})\pm0.013 (\mathrm{syst}). \end{equation*} The mass of the $B_c^+$ meson is determined as $M(B_c^+)=6274.0\pm1.8 (\mathrm{stat})\pm0.4 (\mathrm{syst}) \mathrm{MeV}/c^2$, using the $B_c^+\to J/\psi p\overline{p}\pi^+$ channel.

Figures and captions

Invariant mass distribution for (left) $ B _ c ^+ \rightarrow { J \mskip -3mu/\mskip -2mu\psi \mskip 2mu} p \overline{p}\pi ^+ $ and (right) $ B _ c ^+ \rightarrow { J \mskip -3mu/\mskip -2mu\psi \mskip 2mu} \pi ^+ $ candidates. The superimposed curves show the fitted contributions from signal (dashed), combinatorial background (dotted), misidentification background (dot-dashed) and their sum (solid).

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Fig1a.pdf
Fig1b.pdf [23 KiB]
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Fig1b.pdf

Invariant mass distributions of (left) $M(p\overline{p})$ and (right) $M(p\pi ^+ )$ for data (dots) and simulation (solid) using uniform phase-space model, for $ B _ c ^+ \rightarrow { J \mskip -3mu/\mskip -2mu\psi \mskip 2mu} p \overline{p}\pi ^+ $ decay.

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Animated gif made out of all figures.

PAPER-2014-039.gif
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thumbnail_PAPER-2014-039.gif

Tables and captions

Systematic uncertainties for the $ B _ c ^+ $ mass measurement.

Table_1.pdf [30 KiB]
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Table_1.pdf

Systematic uncertainties (in percent) for the relative branching fraction measurement.

Table_2.pdf [32 KiB]
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Table_2.pdf

Supplementary Material [file]

Supplementary material full pdf

supple[..].pdf [92 KiB]
supplementary.pdf

This ZIP file contains supplemetary material for the publication LHCb-PAPER-2014-039. The files are: Supplementary.pdf : Decribing the thee LHCb measurements of Bc+ mass, and their average. *.pdf, *.png, *.eps, *.C : The results Bc+ mass measurements in variuous formats supp.tex: main latex file used to produce supplementary.pdf, including mass result table

bcComp.pdf [4 KiB]
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bcComp.pdf

Created on 05 November 2019.