Observation of Resonance Structures in ${e}^{+}{e}^{-}\to {\pi }^{+}{\pi }^{-}{\psi }_{2}\left(3823\right)$ and Mass Measurement of ${\psi }_{2}\left(3823\right)$

Using a data sample corresponding to an integrated luminosity of $11.3\text{}\text{}{\mathrm{fb}}^{-1}$ collected at center-of-mass energies from 4.23 to 4.70 GeV with the BESIII detector, we measure the product of the ${e}^{+}{e}^{-}\to {\pi }^{+}{\pi }^{-}{\psi }_{2}\left(3823\right)$ cross section and the branching fraction $B\left[{\psi }_{2}\left(3823\right)\to \gamma {\chi }_{c1}\right]$. For the first time, resonance structure is observed in the cross section line shape of ${e}^{+}{e}^{-}\to {\pi }^{+}{\pi }^{-}{\psi }_{2}\left(3823\right)$ with significances exceeding $5\sigma $. A fit to data with two coherent Breit-Wigner resonances modeling the $\sqrt{s}$-dependent cross section yields $M\left({R}_{1}\right)=4406.9±17.2±4.5\text{}\text{}\mathrm{MeV}/{c}^{2}$, $\Gamma \left({R}_{1}\right)=128.1±37.2±2.3\text{}\text{}\mathrm{MeV}$, and $M\left({R}_{2}\right)=\phantom{\rule{0ex}{0ex}}4647.9±8.6±0.8\text{}\text{}\mathrm{MeV}/{c}^{2}$, $\Gamma \left({R}_{2}\right)=33.1±18.6±4.1\text{}\text{}\mathrm{MeV}$. Though weakly disfavored by the data, a single resonance with $M\left(R\right)=4417.5±26.2±3.5\text{}\text{}\mathrm{MeV}/{c}^{2}$, $\Gamma \left(R\right)=245±48±13\text{}\text{}\mathrm{MeV}$ is also possible to interpret data. This observation deepens our understanding of the nature of the vector charmoniumlike states. The mass of the ${\psi }_{2}\left(3823\right)$ state is measured as $\left(3823.12±0.43±0.13\right)\text{}\text{}\mathrm{MeV}/{c}^{2}$, which is the most precise measurement to date.