We report evidence for a narrow structure, X(5568), in the decay sequence X(5568)→B_{s}^{0}π^{±}, B_{s}^{0}→J/ψϕ, J/ψ→μ^{+}μ^{-}, ϕ→K^{+}K^{-}. This is evidence for the first instance of a hadronic state with valence quarks of four different flavors. The mass and natural width of this state are measured to be m=5567.8±2.9(stat)_{-1.9}^{+0.9}(syst)  MeV/c^{2} and Γ=21.9±6.4(stat)_{-2.5}^{+5.0}(syst)  MeV/c^{2}. If the decay is X(5568)→B_{s}^{*}π^{±}→B_{s}^{0}γπ^{±} with an unseen γ, m(X(5568)) will be shifted up by m(B_{s}^{*})-m(B_{s}^{0})∼49  MeV/c^{2}. This measurement is based on 10.4  fb^{-1} of pp[over ¯] collision data at sqrt[s]=1.96  TeV collected by the D0 experiment at the Fermilab Tevatron collider.

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We investigate the decay B + → J/ψφK + in a search for the X(4140) state, a narrow threshold resonance in the J/ψφ system. The data sample corresponds to an integrated luminosity of 10.4 fb −1 of pp collisions at √ s = 1.96 TeV collected by the D0 experiment at the Fermilab Tevatron collider.We observe a mass peak with a statistical significance of 3.1 standard deviations and measure its invariant mass to be M = 4159.0 ± 4.3 (stat) ± 6.6 (syst) MeV and its width to be Γ = 19.9 ± 12.6 (stat) +1.0 −8.0 (syst) MeV. Identifying this mass peak as the X(4140), we measure, for M (J/ψφ) < 4.59 GeV, the relative branching fraction B rel = B(B + → X(4140)K + )/B(B + → J/ψφK + ) to be 21 ± 8 (stat) ± 4 (syst)%. In addition, the data can accommodate the presence of a second enhancement at a mass of 4328.5 ± 12.0 MeV.