Observation of Charmonium $h_c$ Radiative Decays to Multiple Light Hadrons and the Tensor State $f_2(1270)$

Abstract

Using $\ddot{I}ˆ(3686)\to \ddot{I}{€}^0{h}_c$ decays from a data sample of $(27.12\pm 0.14)\times 10^8$ $\ddot{I}ˆ(3686)$ events collected by the BESIII detector at the BEPCII collider, $h_c$ radiative decays to ${\hat{I}}^3\ddot{I}{€}^{+}\ddot{I}{€}^{-},{\hat{I}}^3\ddot{I}{€}^{+}\ddot{I}{€}^{-}\hat{I}\cdot ,\gamma 2(\ddot{I}{€}^{+}\ddot{I}{€}^{-})$, and ${\hat{I}}^{3}p\bar{p}$ are observed for the first time, each with a significance greater than $5\ddot{I}ƒ$. The corresponding branching fractions are measured. Furthermore, intermediate states below 2.8 GeV/$c^2$ are investigated, leading to the first observation of the decay process of $h_c\to {\hat{I}}^3{f}_2(1270)\to {\hat{I}}^3\ddot{I}{€}^{+}\ddot{I}{€}^{-}$ with a significance of $5.5\ddot{I}ƒ$. This observation represents the first instance of $h_c$ radiative decay to a tensor state.