Search for the X(5568) state in B0s pi+- decays

A search for resonance-like structures in the $\mathrm{B}^0_\mathrm{s} \pi^\pm$~invariant mass spectrum is performed using an integrated luminosity of 19.7~fb$^{-1}$ of $pp$~collisions at $\sqrt{s} = 8$~TeV collected by the CMS experiment. The $\mathrm{B}^0_\mathrm{s}$~candidates are reconstructed in the decay chain $\mathrm{B}^0_\mathrm{s} \rightarrow \mathrm{J}/\psi \phi$, $\mathrm{J}/\psi \rightarrow \mu^+ \mu^-$, $\phi \rightarrow \mathrm{K}^+ \mathrm{K^-}$. With about 48,000 $\mathrm{B}^0_\mathrm{s}$-mesons reconstructed, the $\mathrm{B}^0_\mathrm{s}\pi^\pm$~invariant mass distributions do not show any unexpected structures for different kinematic requirements imposed to the $\pi^\pm$, $\mathrm{B}^0_\mathrm{s}$ and $\mathrm{B}^0_\mathrm{s} \pi^\pm$~candidates. An upper limit on the relative production of $X(5568)$ and $\mathrm{B}^0_\mathrm{s}$ multiplied by the branching fraction of the decay $X(5568) \rightarrow \mathrm{B}^0_\mathrm{s} \pi^\pm$ is estimated to be $3.9\%$ at 95\% CL in the most conservative case.