Evidence for a new resonance and search for the Y(4140) in $γγ\to ϕJ/ψ$

Abstract

The process $γγ\to ϕ\jpsi$ is measured for $ϕ\jpsi$ masses between threshold and 5 GeV/${\it c}^2$, 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 $(4350.6^{+4.6}_{-5.1}(\rm{stat})\pm 0.7(\rm{syst})) \hbox{MeV}/{\it c}^2$ and $(13^{+18}_{-9}(\rm{stat})\pm 4(\rm{syst})) \hbox{MeV}$, respectively. The product of its two-photon decay width and branching fraction to $ϕ\jpsi$ is $(6.7^{+3.2}_{-2.4}(\rm{stat}) \pm 1.1(\rm{syst})) \hbox{eV}$ for $J^P=0^+$, or $(1.5^{+0.7}_{-0.6}(\rm{stat}) \pm 0.3(\rm{syst})) \hbox{eV}$ for $J^P=2^+$. No signal for the $Y(4140)\to ϕ\jpsi$ structure reported by the CDF Collaboration in $B\to K^+ ϕ\jpsi$ decays is observed, and limits of $Γ_{γγ}(Y(4140)) \BR(Y(4140)\toϕ\jpsi)<41 \hbox{eV}$ for $J^P=0^+$ or $<6.0 \hbox{eV}$ for $J^P=2^+$ are determined at the 90% C.L. This disfavors the scenario in which the Y(4140) is a $D_{s}^{\ast+} {D}_{s}^{\ast-}$ molecule.

9 pages, 3 figures, publication in Phys. Rev. Lett. 104, 112004, 2010