Hidden Charm Spectroscopy from Tevatron

The observation of a narrow structure near the J/ψ φ threshold in exclusive B → J/ψ φK decays produced in pp̄ collisions at √ s = 1.96TeV is reported. A signal of 19 ± 6(stat) ± 3(syst) events, with statistical significance of 5.0 standard deviations, is seen in a data sample corresponding to an integrated luminosity of 6.0 fb, collected by the CDF II detector. The mass and natural width of the structure are determined to be m = 4143.4 −3.0 (stat) ± 0.6(syst)MeV/c and Γ = 15.3 −6.1 (stat) ± 2.5(syst)MeV/c, consistent with the previous measurements reported as evidence of the Y (4140).