# Observation of $e^{+}e^{-} \to \eta h_{c}$ at center-of-mass energies from 4.085 to 4.600 GeV

## TL;DR

This paper reports the first observation of the process e+e- to eta hc at specific energies, measuring cross sections and providing evidence for this production in electron-positron collisions.

## Contribution

It presents the first experimental observation of e+e- to eta hc and measures its cross sections at various energies, expanding understanding of charmonium-like states.

## Key findings

- Significant signals at 4.226 GeV with a cross section of ~9.5 pb.
- Evidence at 4.358 GeV with a cross section of ~10.0 pb.
- Upper limits set for other energies between 4.085 and 4.600 GeV.

## Abstract

We observe for the first time the process $e^{+}e^{-} \rightarrow \eta h_c$ with data collected by the BESIII experiment. Significant signals are observed at the center-of-mass energy $\sqrt{s}=4.226$ GeV, and the Born cross section is measured to be $(9.5^{+2.2}_{-2.0} \pm 2.7)$ pb. Evidence for $\eta h_c$ is observed at $\sqrt{s}=4.358$ GeV with a Born cross section of $(10.0^{+3.1}_{-2.7} \pm 2.6)$ pb, and upper limits on the production cross section at other center-of-mass energies between 4.085 and 4.600 GeV are determined.