A search for the $B^0_s \rightarrow D^{*\pm} D^\mp$ decay is performed using proton-proton collision data at centre-of-mass energies of $7$, $8$ and $13 \text{TeV}$ collected by the LHCb experiment, corresponding to an integrated luminosity of $9 \text{fb}^{-1}$. The decay is observed with a high significance and its branching fraction relative to the $B^0 \rightarrow D^{*\pm} D^\mp$ decay is measured to be \begin{align*} \frac{\mathcal{B}(B_s^0 \rightarrow D^{\ast \pm} D^{\mp}) }{\mathcal{B}(B^0 \rightarrow D^{\ast \pm} D^{\mp}) } = 0.137 \pm 0.017 \pm 0.002 \pm 0.006 , \end{align*} where the first uncertainty is statistical, the second systematic and the third is due to the uncertainty on the ratio of the $B_s^0$ and $B^0$ hadronisation fractions.
(Left) Tree-level and (right) penguin diagrams contributing to $ B ^0 \rightarrow D _{(s)}^{(*)\pm} D ^{(*)\mp}$ and $ B ^0_ s \rightarrow D _{(s)}^{(*)\pm} D _{s}^{(*)\mp}$ decays. |
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(Left) $ W $ -exchange and (right) penguin-annihilation diagrams contributing to $ B _{(s)}^{0} \rightarrow D _{(s)}^{(*)+} D _{(s)}^{(*)-}$ decays. |
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The $ D ^{*\pm}$ $ D ^\mp$ mass distributions for (top left) 2011--2012, (top right) 2015--2016, (bottom left) 2017--2018 data in logarithmic scale, and (bottom right) the combined data sample in linear scale. The total fit projection is shown as the blue solid line. The green dotted and the red dashed lines correspond to the signal contributions for the $ B ^0$ and $ B ^0_ s $ decays, respectively. The orange dash-dotted line corresponds to the combinatorial background contribution. The $ B ^0 \rightarrow D ^{*\pm} D ^{*\mp} $ and $ B ^0_ s \rightarrow D ^{*\pm} D ^{*\mp} $ background components are described by the magenta long-dashed and the cyan long-dashed-two-dotted lines. |
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Animated gif made out of all figures. |
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Systematic uncertainties on $\mathcal{B} ( B ^0_ s \rightarrow D ^{*\pm} D ^\mp )/\mathcal{B} ( B ^0 \rightarrow D ^{*\pm} D ^\mp )$. The systematic uncertainty is given relative to the measured value. |
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Created on 02 May 2024.