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Searches for $B^0_{(s)} \to J/\psi p\bar{p}$ and $B^+ \to J/\psi p\bar{p}\pi^+$ decays

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Abstract

The results of searches for $B^{0}_{(s)} \rightarrow J/{\psi} p \overline{p}$ and $B^{+} \to J/{\psi} p \overline{p} {\pi}^{+}$ decays are reported. The analysis is based on a data sample, corresponding to an integrated luminosity of 1.0 fb$^{-1}$ of $pp$ collisions, collected with the LHCb detector. An excess with 2.8$\,\sigma$ significance is seen for the decay $B^{0}_{s} \to J/{\psi} p \overline{p}$ and an upper limit on the branching fraction is set at the 90 % confidence level: ${\cal B}(B^{0}_{s} \to J/{\psi} p \overline{p}) < 4.8 \times 10^{-6}$, which is the first such limit. No significant signals are seen for $B^{0} \to J/{\psi} p \overline{p}$ and $B^{+} \to J/{\psi} p \overline{p} {\pi}^{+}$ decays, for which the corresponding limits are set: ${\cal{B}}(B^{0} \to J/{\psi} p \overline{p}) < 5.2 \times 10^{-7}$, which significantly improves the existing limit; and ${\cal{B}}(B^{+} \to J/{\psi} p \overline{p} {\pi}^{+}) < 5.0 \times 10^{-7}$, which is the first limit on this branching fraction.

Figures and captions

Invariant mass distribution of (a) $ B ^0_{( s )} \!\rightarrow { J \mskip -3mu/\mskip -2mu\psi \mskip 2mu} p \overline p $ and (b) $ B ^+ \!\rightarrow { J \mskip -3mu/\mskip -2mu\psi \mskip 2mu} p \overline p \pi ^+ $ candidates after the full selection. Each component of the fit model is displayed on the plot: the signal PDFs are represented by the dot-dashed violet and dashed green line; the combinatorial background by the dotted red line; and the overall fit is given by the solid blue line. The fit pulls are also shown, with the red lines corresponding to $2\,\sigma$. The $ B ^+ \!\rightarrow { J \mskip -3mu/\mskip -2mu\psi \mskip 2mu} p \overline p \pi ^+ $ yield is multiplied by five in order to make the signal position visible.

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Invariant mass distribution of $ B ^0_{( s )} \!\rightarrow { J \mskip -3mu/\mskip -2mu\psi \mskip 2mu} \pi ^+ \pi ^- $ candidates after the full selection for the (a) $ B ^0_{( s )} \!\rightarrow { J \mskip -3mu/\mskip -2mu\psi \mskip 2mu} p \overline p $ and (c) $ B ^+ \!\rightarrow { J \mskip -3mu/\mskip -2mu\psi \mskip 2mu} p \overline p \pi ^+ $ searches. The corresponding logarithmic plots are shown in (b) and (d). Each component of the fit is represented on the plot: $ B ^0 \!\rightarrow { J \mskip -3mu/\mskip -2mu\psi \mskip 2mu} \pi ^+ \pi ^- $ signal (green dashed), $ B ^0_ s \!\rightarrow { J \mskip -3mu/\mskip -2mu\psi \mskip 2mu} \pi ^+ \pi ^- $ signal (violet dot-dashed), $ B ^0 \!\rightarrow { J \mskip -3mu/\mskip -2mu\psi \mskip 2mu} K ^+ \pi ^- $ background (black falling hashed), ${ B ^0_ s \!\rightarrow { J \mskip -3mu/\mskip -2mu\psi \mskip 2mu} \eta' }$ background (cyan rising hashed), and combinatorial background (red dotted). The overall fit is represented by the solid blue line.

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Negative log-likelihood profiles for the (a) $ B ^0 \!\rightarrow { J \mskip -3mu/\mskip -2mu\psi \mskip 2mu} p \overline p $ , (b) $ B ^0_ s \!\rightarrow { J \mskip -3mu/\mskip -2mu\psi \mskip 2mu} p \overline p $ , and (c) $ B ^+ \!\rightarrow { J \mskip -3mu/\mskip -2mu\psi \mskip 2mu} p \overline p \pi ^+ $ signal yields. The red dashed line corresponds to the statistical-only profile while the blue line includes all the systematic uncertainties.

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Animated gif made out of all figures.

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Tables and captions

Systematic uncertainties on the branching fraction ratios of the decays $ B ^0 \!\rightarrow { J \mskip -3mu/\mskip -2mu\psi \mskip 2mu} p \overline p $ , $ B ^0_ s \!\rightarrow { J \mskip -3mu/\mskip -2mu\psi \mskip 2mu} p \overline p $ and $ B ^+ \!\rightarrow { J \mskip -3mu/\mskip -2mu\psi \mskip 2mu} p \overline p \pi ^+ $ measured relative to $ B ^0_ s \!\rightarrow { J \mskip -3mu/\mskip -2mu\psi \mskip 2mu} \pi ^+ \pi ^- $ . The total is obtained from the sum in quadrature of all contributions.

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