Observation of Resonance Structures in e^{+}e^{-}→π^{+}π^{-}ψ_{2}(3823) and Mass Measurement of ψ_{2}(3823)

Using a data sample corresponding to an integrated luminosity of 11.3 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(-) -> pi(+) pi(-) psi(2)(3823) cross section and the branching fraction B[psi(2) (3823) -> gamma chi(c1)]. For the first time, resonance structure is observed in the cross section line shape of e(+) e(-) -> pi(+) pi(-) psi(2)(3823) with significances exceeding 5 sigma. A fit to data with two coherent Breit-Wigner resonances modeling the root s-dependent cross section yields M(R-1) = 4406.9 +/- 17.2 +/- 4.5 MeV/c(2), Gamma(R-1) = 128.1 +/- 37.2 +/- 2.3 MeV, and M(R-2) = 4647.9 +/- 8.6 +/- 0.8 MeV/c2, Gamma(R-2) = 33.1 +/- 18.6 +/- 4.1 MeV. Though weakly disfavored by the data, a single resonance with M(R) = 4417.5 +/- 26.2 +/- 3.5 MeV/c(2), Gamma(R) = 245 +/- 48 +/- 13 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)(3823) state is measured as (3823.12 +/- 0.43 +/- 0.13) MeV/c(2), which is the most precise measurement to date.