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Search for the rare decays $B^{0}\to J/\psi \gamma$ and $B^{0}_{s} \to J/\psi \gamma$

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Abstract

A search for the rare decay of a $B^{0}$ or $B^{0}_{s}$ meson into the final state $J/\psi\gamma$ is performed, using data collected by the LHCb experiment in $pp$ collisions at $\sqrt{s}=7$ and $8$ TeV, corresponding to an integrated luminosity of 3 fb$^{-1}$. The observed number of signal candidates is consistent with a background-only hypothesis. Branching fraction values larger than $1.7\times 10^{-6}$ for the $B^{0}\to J/\psi\gamma$ decay mode are excluded at 90% confidence level. For the $B^{0}_{s}\to J/\psi\gamma$ decay mode, branching fraction values larger than $7.4\times 10^{-6}$ are excluded at 90% confidence level, this is the first branching fraction limit for this decay.

Figures and captions

Feynman diagram of the leading contribution to the decay $ B _{(s)}\rightarrow { J \mskip -3mu/\mskip -2mu\psi \mskip 2mu} \gamma$ in the Standard Model. Radiation of the photon from the other quarks is suppressed by a factor of $\Lambda_{\rm{QCD}}/m_{b}$ [1].

Bs2Jps[..].pdf [9 KiB]
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Bs2Jpsigamma_feyn.pdf

Mass distribution of signal candidates with the fit result overlaid, allowing for a $ B ^0_ s \!\rightarrow { J \mskip -3mu/\mskip -2mu\psi \mskip 2mu} \gamma$ signal.

data_fit.pdf [34 KiB]
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data_fit.pdf

Observed $\mathrm{CL}_{\mathrm{S}}$ (black points), expected $\mathrm{CL}_{\mathrm{S}}$ (continuous line) and expected 1 and 2 $\sigma$ uncertainty (shaded bands) value as a function of the hypothesized branching fraction for the $ B ^0_ s \rightarrow { J \mskip -3mu/\mskip -2mu\psi \mskip 2mu} \gamma$ decay (left) and $ B ^0 \rightarrow { J \mskip -3mu/\mskip -2mu\psi \mskip 2mu} \gamma$ decay (right). The dashed line represents the branching fraction excluded at 90% C.L..

cls.pdf [15 KiB]
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cls.pdf
cls_bd.pdf [15 KiB]
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cls_bd.pdf

Animated gif made out of all figures.

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Tables and captions

Summary of systematic uncertainties. Each source is listed with the corresponding uncertainty on the branching fraction for the signal.

Table_1.pdf [45 KiB]
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tex code
Table_1.pdf

Supplementary Material [file]

Supplementary material full pdf

supple[..].pdf [209 KiB]
supplementary.pdf
Fig1-S.pdf [17 KiB]
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Fig2-S.pdf [49 KiB]
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Fig3a-S.pdf [34 KiB]
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Fig3a-S.pdf
Fig3b-S.pdf [33 KiB]
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Created on 09 December 2018.Citation count from INSPIRE on 18 December 2018.