Observation of $e^{+}e^{-} \to \eta^{\prime} J/\psi$ at center-of-mass energies between 4.189 and 4.600 GeV

TL;DR

This paper reports the first observation of the process e+e- to eta' J/psi at specific energies, measuring its cross sections and establishing its significance with high confidence.

Contribution

The first observation and measurement of the e+e- to eta' J/psi process at center-of-mass energies between 4.189 and 4.600 GeV, including cross section values at specific energies.

Findings

Observation with 8.6σ and 7.3σ significance at 4.226 and 4.258 GeV

Measured Born cross sections of approximately 3.7 and 3.9 pb at these energies

Upper limits set at 12 other energy points

Abstract

The process $e^{+}e^{-}\to \eta^{\prime} J/\psi$ is observed for the first time with a statistical significance of $8.6\sigma$ at center-of-mass energy $\sqrt{s} = 4.226$ GeV and $7.3\sigma$ at $\sqrt{s} = 4.258$ GeV using data samples collected with the BESIII detector. The Born cross sections are measured to be $(3.7 \pm 0.7 \pm 0.3)$ and $(3.9 \pm 0.8 \pm 0.3)$ pb at $\sqrt{s} = 4.226$ and $4.258$ GeV, respectively, where the first errors are statistical and the second systematic. Upper limits at the 90% confidence level of the Born cross sections are also reported at other 12 energy points.