Observation of the B${}_{\mathrm{s}}^0$ $\to$ X(3872)$\varphi$ decay

Using a data sample of proton-proton collisions at $\sqrt{s}=$ 13 TeV, corresponding to an integrated luminosity of 140 fb${}^{-1}$ collected by the CMS experiment in 2016-2018, the B${}_{\mathrm{s}}^0$ $\to$ X(3872)$\varphi$ decay is observed. Decays into J/$\psi {\pi }^{+}{\pi }^{-}$ and K${}^{+}$K${}^{-}$ are used to reconstruct, respectively, the X(3872) and $\varphi$. The ratio of the product of branching fractions $\mathcal{B}($B${}_{\mathrm{s}}^0$ $\to$ X(3872)$\varphi )\mathcal{B}($X(3872) $\to$ J$\mathrm{/}\psi {\pi }^{+}{\pi }^{-})$ to the product $\mathcal{B}($B${}_{\mathrm{s}}^0$ $\to$ $\psi$(2S)$\varphi )\mathcal{B}(\psi$(2S) $\to$ J/$\psi {\pi }^{+}{\pi }^{-})$ is measured to be (2.21 $\pm$ 0.29 (stat) $\pm$ 0.17 (syst))%. The ratio $\mathcal{B}($B${}_{\mathrm{s}}^0$ $\to$ X(3872)$\phi) / $\mathcal{B}$($B$^{0}$ $\to$ X(3872)K${}^0)$ is found to be consistent with one, while the ratio $\mathcal{B}($B${}_{\mathrm{s}}^0$ $\to$ X(3872)$\phi) / $\mathcal{B}$($B$^+$ $\to$ X(3872)K${}^{+})$ is two times smaller. This suggests a difference in the production dynamics of the X(3872) in B${}^0$ and B${}_{\mathrm{s}}^0$ meson decays compared to B${}^{+}$. The reported observation may shed new light on the nature of the X(3872) particle.