Olivier Schneider, Yiming Li, Mingkui Wang, Chao Wang, Tagir Aushev, Sun Hee Kim, Donghyun Kim, Xiao Wang
We report the first observation of the radiative decay of the Upsilon(1S) into a charmonium state. The significance of the observed signal of Upsilon(1S) -> gamma chi(c1) is 6.3 standard deviations including systematics. The branching fraction is calculate ...
AMER PHYSICAL SOC2020