Search for charmonium and charmonium-like states in ${\rm Y}(1S)$ and ${\rm Y}(2S)$ radiative decays

Abstract

Using samples of 102 million ${\rm Y}(1S)$ and 158 million ${\rm Y}(2S)$ event samples collected with the Belle detector, we report on the first search for charge-parity-even charmonium and charmonium-like states in ${\rm Y}(1S)$ and ${\rm Y}(2S)$ radiative decays. No significant ${\chi }_{cJ}$ or ${\eta }_c$ signal is observed and 90% C.L. limits on $\BR(Υ(nS)\to γχ_{cJ})$ ($n=1,2$ and $J=1,2,3$) are obtained. No significant signal of any charmonium-like state is observed. The product branching fraction limits $\BR(Υ(nS)\to γX(3872))$ $\BR(X(3872)\toπ^+π^-\jpsi)$, $\BR(Υ(nS)\to γX(3872))$ $\BR(X(3872)\toπ^+π^-π^0 \jpsi)$, $\BR(Υ(nS)\to γX(3915))$ $\BR(X(3915)\toω\jpsi)$, and $\BR$ $(Υ(1S)\to γY(4140))\BR(Y(4140)\to ϕ\jpsi)$ ($n=1,2$) are obtained at the 90% C.L. At the same time, $\BR(Υ(2S) \to γX(4350))\BR(X(4350)\toϕ\jpsi))$ is also determined at the 90% C.L. Furthermore, no evidence is found for excited charmonium states below 4.8 GeV/$c^2$.

arXiv comment8 pages, 3 figures, 1 table; to appear in the proceedings of The 5th International Workshop on Charm Physics (Charm 2012)