Observation of e+e-? ??(2S) at center-of-mass energies from 4.236 to 4.600 GeV

Abstract

Using a total of 5.25 fb(-1) of e(+)e(-) collision data with center-of-mass energies from 4.236 to 4.600 GeV, we report the first observation of the process e(+)e(-)-> eta psi(2S) with a statistical significance of 4.9 standard deviations. The data sets were collected by the BESIII detector operating at the BEPCII storage ring. We measure the yield of events integrated over center-of-mass energies and also present the energy dependence of the measured cross section.