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The cross sections of the process $e^{+}e^{-} \to \eta J/\psi$ atcenter-of-mass energies ($\sqrt{s}$) between 3.81 and 4.60 GeV are measuredwith high precision by using data samples collected with the BESIII detectoroperating at the BEPCII storage ring. Three structures are observed byanalyzing the lineshape of the measured cross sections, and amaximum-likelihood fit including three resonances is performed by assuming thelowest lying structure is the $\psi(4040)$. For the other resonances, we obtainmasses of $(4218.7 \pm 4.0 \pm 2.5)$ and $(4380.4 \pm 14.2 \pm 1.8)$MeV/c$^{2}$ with corresponding widths of $(82.5 \pm 5.9 \pm 0.5)$ and $(147.0\pm 63.0 \pm 25.8)$ MeV, respectively, where the first uncertainties arestatistical and the second ones systematic. The measured resonant parametersare consistent with those of the $Y(4220)$ and $Y(4360)$ from pr eviousmeasurements of different final states. For the first time, we observe thedecays of the $Y(4220)$ and $Y(4360)$ into $\eta J/\psi$ final states.

Observation of the $Y(4220)$ and $Y(4360)$ in the process $e^{+}e^{-} \to \eta J/\psi$