Statistical combination of searches for the ${\mathrm{X}}^{\pm }(5568)$ state decaying into ${\mathrm{B}}_{\mathrm{s}}^0{\pi }^{\pm }$

Abstract

A statistical combination of the search results for the narrow ${\mathrm{X}}^{\pm }(5568)$ resonance decaying into ${\mathrm{B}}_{\mathrm{s}}^0{\pi }^{+}$ is reported, based on published results from the ATLAS, CMS, CDF and LHCb Collaborations. A structure in the invariant mass distribution of ${\mathrm{B}}_{\mathrm{s}}^0{\pi }^{+}$ has been observed by the D0 Collaboration with a mass value of 5568 MeV but not confirmed by any of the latest searches from the other Collaborations. Limits have been set on the relative production rate ${\rho }_{\mathrm{X}}$ of the ${\mathrm{X}}^{\pm }(5568)$ and ${\mathrm{B}}_{\mathrm{s}}^0$ states, times the branching ratio for the decay ${\mathrm{X}}^{\pm }(5568)\to {\mathrm{B}}_{\mathrm{s}}^0{\pi }^{\pm }$. By applying a statistical combination of limits set by the three LHC experiments, we derive a limit at 95\% Confidence Level of ${\rho }_X<0.0092$ for $p_T(B_s^0)>$ 10 GeV, and ${\rho }_X<0.0091$ for $p_T(B_s^0)>$ 15 GeV, superseding the previous most stringent upper limits. The effect of including the CDF result in the combination is also discussed.

4 pages, 4 figures, 2 tables