Search for charmonium and charmonium-like states in Υ(2S) radiative decays
Using a sample of 158 million Υ(2S) events collected with the Belle detector, charmonium and charmonium-like states with even charge parity are searched for in Υ(2S) radiative decays. No significant χ_{cJ} or η_c signal is observed and the following upper limits at 90% confidence level (C.L.) are obtained: BR(Υ(2S)\to γχ_{c0})< 1.0 \times 10^{-4}, BR(Υ(2S) \to γχ_{c1})<3.6 \times 10^{-6}, BR(Υ(2S) \to γχ_{c2})<1.5 \times 10^{-5}, and BR(Υ(2S) \to γη_c)< 2.7 \times 10^{-5}. No significant signal of any charmonium-like state is observed, and we obtain the limits \BR(Υ(2S)\to γX(3872))\times\BR(X(3872)\toπ^+π^-J/ψ)< 0.8 \times 10^{-6}, BR(Υ(2S) \to γX(3872))\times BR(X(3872)\toπ^+π^-π^0 J/ψ)< 2.4\times 10^{-6}, BR(Υ(2S) \to γX(3915))\times BR(X(3915)\toωJ/ψ)< 2.8\times 10^{-6}, BR(Υ(2S) \to γY(4140))\times BR(Y(4140)\toϕJ/ψ)) < 1.2\times 10^{-6}, and BR(Υ(2S) \to γX(4350))\times BR(X(4350)\toϕJ/ψ))< 1.3\times 10^{-6} at 90% C.L.