Evidence for a new resonance and search for the Y(4140) in γγ→ ϕJ/ψ
The Belle Collaboration · Shen, C. P.
Original · EN
The process γγ→ ϕ is measured for ϕ masses between threshold and 5 GeV/ c², using a data sample of 825 fb⁻¹ collected with the Belle detector. A narrow peak of 8.8⁺⁴.²₋₃.₂ events, with a significance of 3.2 standard deviations including systematic uncertainty, is observed. The mass and natural width of the structure (named X(4350)) are measured to be (4350.6⁺⁴.⁶₋₅.₁(stat)± 0.7(syst)) MeV/ c² and (13⁺¹⁸₋₉(stat)± 4(syst)) MeV, respectively. The product of its two-photon decay width and branching fraction to ϕ is (6.7⁺³.²₋₂.₄(stat) ± 1.1(syst)) eV for Jᵖ=0+, or (1.5⁺⁰.⁷₋₀.₆(stat) ± 0.3(syst)) eV for Jᵖ=2+. No signal for the Y(4140)→ ϕ structure reported by the CDF Collaboration in B→ K+ ϕ decays is observed, and limits of Γᵧᵧ(Y(4140)) (Y(4140)→ϕ)<41 eV for Jᵖ=0+ or <6.0 eV for Jᵖ=2+ are determined at the 90% C.L. This disfavors the scenario in which the Y(4140) is a Dₛ+ Dₛ- molecule.
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