Observation of the Y (4140) structure in the J/ψφ mass spectrum in B± → J/ψφK± decays

The observation of the Y (4140) structure in B± → J/ψφK± decays produced in ¯pp collisions at √s = 1.96 TeV is reported with a statistical significance greater than 5 standard deviations. A fit to the J/ψφ mass spectrum is performed assuming the presence of a Breit–Wigner resonance. The fit yields a signal of 19 ± 6 (stat) ± 3 (syst) resonance events, and resonance mass and width of 4143.4+2.9 −3.0 (stat)±0.6 (syst) MeV/c2 and 15.3+10.4 −6.1 (stat) ± 2.5 (syst) MeV/c2, respectively. The parameters of this resonance-like structure are consistent with values reported from an earlier CDF analysis. - PACS Nos.: 14.40.Gx, 13.25.Gv, 12.39.Mk