Study of the X± (5568) state with semileptonic decays of the Bs0 meson STUDY of the X± (5568) STATE with ⋯ V. M. ABAZOV et al.

We present a study of the X±(5568) using semileptonic decays of the Bs0 meson using the full run II integrated luminosity of 10.4 fb-1 in proton-antiproton collisions at a center of mass energy of 1.96 TeV collected with the D0 detector at the Fermilab Tevatron Collider. We report evidence for a narrow structure, X±(5568), in the decay sequence X±(5568)→Bs0π± where Bs0→μ Ds±X, Ds±→φπ± which is consistent with the previous measurement by the D0 Collaboration in the hadronic decay mode, X±(5568)→Bs0π± where Bs0→J/ψφ. The mass and width of this state are measured using a combined fit of the hadronic and semileptonic data, yielding m=5566.9-3.1+3.2(stat)-1.2+0.6(syst) MeV/c2, Γ=18.6-6.1+7.9(stat)-3.8+3.5(syst) MeV/c2 with a significance of 6.7σ.