Search for ψ(2S) production in e+e- annihilations at 4.03 GeV

A search is performed for the production of the ψ(2S) in e^+e^- annihilation at a center-of-mass energy of 4.03 GeV using the BES detector operated at the Beijing Electron Positron Collider (BEPC). The kinematic features of the reconstructed ψ(2S) signal are consistent with its being produced only in association with an energetic photon resulting from initial state radiation (ISR). Limits are placed on ψ(2S) production from the decay of unknown charmonia or metastable hybrids that might be produced in e^+e^- annihilations at 4.03 GeV. Under the assumption that the observed cross section for ψ(2S) production is due entirely to ISR, the partial width Γ_(ee) of the ψ(2S) is measured to be 2.07±0.32keV.