Observation of Charmonium $h_{c}$ Radiative Decays to Multiple Light Hadrons and the Tensor State $f_2(1270)$

TL;DR

This paper reports the first observation of specific radiative decay modes of the $h_c$ charmonium state, including its decay to a tensor meson, using a large data sample from the BESIII detector, with measured branching fractions.

Contribution

It presents the first measurements of $h_c$ radiative decays to multiple light hadrons and the tensor state $f_2(1270)$, expanding understanding of charmonium decay channels.

Findings

First observation of $h_c$ radiative decays to $ ho ext{-}like$ states.

First measurement of $h_c$ decay to $f_2(1270)$.

Branching fractions for these decay modes are provided.

Abstract

Using $\psi(3686)\rightarrow \pi^{0} h_{c}$ decays from a data sample of $(27.12\pm0.14)\times10^{8}$ $\psi(3686)$ events collected by the BESIII detector at the BEPCII collider, $h_c$ radiative decays to $\gamma\pi^{+}\pi^{-},~\gamma\pi^{+}\pi^{-}\eta,~\gamma2(\pi^{+}\pi^{-})$, and $\gamma p\bar{p}$ are observed for the first time, each with a significance greater than $5\sigma$. 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 $h_c\rightarrow\gamma f_{2}(1270)\rightarrow\gamma\pi^{+}\pi^{-}$ with a significance of $5.5\,\sigma$. This observation represents the first instance of $h_c$ radiative decay to a tensor state.