Measurement of ${e}^{+}{e}^{-}\to \eta J/\psi $ cross section from $\sqrt{s}=3.808\text{}\text{}\mathrm{GeV}$ to 4.951 GeV

Using data samples with an integrated luminosity of $22.42\text{}\text{}{\mathrm{fb}}^{-1}$ collected by the BESIII detector operating at the BEPCII storage ring, we measure the cross sections of the ${e}^{+}{e}^{-}\to \eta J/\psi $ process at center-of-mass energies from 3.808 to 4.951 GeV. Three structures are observed in the line shape of the measured cross sections. A maximum-likelihood fit with $\psi \left(4040\right)$, two additional resonances, and a nonresonant component are performed. The mass and width of the first additional state are $\left(4219.7±2.5±4.5\right)\text{}\text{}\mathrm{MeV}/{c}^{2}$ and $\left(80.7±4.4±1.4\right)\text{}\text{}\mathrm{MeV}$, respectively, consistent with the $\psi \left(4230\right)$. For the second state, the mass and width are $\left(4386±13±17\right)\text{}\text{}\mathrm{MeV}/{c}^{2}$ and $\left(177±32±13\right)\text{}\text{}\mathrm{MeV}$, respectively, consistent with the $\psi \left(4360\right)$. The first uncertainties are statistical, and the second ones are systematic. The statistical significance of $\psi \left(4040\right)$ is $8.0\sigma $ and those for $\psi \left(4230\right)$ and $\psi \left(4360\right)$ are more than $10.0\sigma $.