Observation of the radiative decays of ${\rm Y}(1S)$ to ${\chi }_{c1}$

P. Katrenko, I. Adachi, H. Aihara +166

We report the first observation of the radiative decay of the ${\rm Y}(1S)$ into a charmonium state. The statistical significance of the observed signal of ${\rm Y}(1S)\to \gamma {\chi }_{c1}$ is 6.3 sta…