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

Abstract

Using a sample of 102 million ${\rm Y}(1S)$ events collected with the Belle detector, we report on the first search for charge-parity-even charmonium and charmonium-like states in ${\rm Y}(1S)$ radiative decays. No significant ${\chi }_{cJ}$ or ${\eta }_c$ signal is observed and 90% C.L. limits on $\text{BR}({\rm Y}(1S)\to \gamma {\chi }_{c0})<6.5\times 10^{-4}$, $\text{BR}({\rm Y}(1S)\to \gamma {\chi }_{c1})<2.3\times 10^{-5}$, $\text{BR}({\rm Y}(1S)\to \gamma {\chi }_{c2})<7.6\times 10^{-6}$, and $\text{BR}({\rm Y}(1S)\to \gamma {\eta }_c)<5.7\times 10^{-5}$ are obtained. The product branching fraction limits $\text{BR}({\rm Y}(1S)\to \gamma X(3872))\text{BR}(X(3872)\to {\pi }^{+}{\pi }^{-}\text{jpsi})<1.6\times 10^{-6}$, $\text{BR}({\rm Y}(1S)\to \gamma X(3872))\text{BR}(X(3872)\to {\pi }^{+}{\pi }^{-}{\pi }^0\text{jpsi})<2.8\times 10^{-6}$, $\text{BR}({\rm Y}(1S)\to \gamma X(3915))\text{BR}(X(3915)\to \omega \text{jpsi})<3.0\times 10^{-6}$, and $\text{BR}({\rm Y}(1S)\to \gamma Y(4140))\text{BR}(Y(4140)\to \varphi \text{jpsi})<2.2\times 10^{-6}$ are obtained at the 90% C.L. Furthermore, no evidence is found for excited charmonium states below 4.8 GeV/$c^2$.

Comments: 9 pages, 3 figures. Minor corrections to etac mass fit. Accepted for publication in PRD(RC)