Observation of the Y(4220) and Y(4390) in the process e(+)e(-) -> eta J/psi

Abstract

The cross sections of the process e(+)e(-) -> eta J/psi lip at center-of-mass energies (root s) between 3.81 and 4.60 GeV are measured with high precision by using data samples collected with the BESIII detector operating at the BEPCII storage ring. Three structures are observed by analyzing the line shape of the measured cross sections, and a maximum-likelihood fit including three resonances is performed by assuming the lowest lying structure is the psi(4040). For the other resonances, we obtain masses of (4218.6 +/- 3.8 +/- 2.5) and (4382.0 +/- 13.3 +/- 1.7) MeV/c(2) with corresponding widths of (82.0 +/- 5.7 +/- 0.4) and (135.8 +/- 60.8 +/- 22.5) MeV, respectively, where the first uncertainties are statistical and the second ones systematic. The measured resonant parameters are consistent with those of the Y(4220) and Y(4390) from previous measurements of different final states. For the first time, we observe the decays of the Y(4220) and Y(4390) into eta J/psi final states.