Search forψ(2S)production ine+e−annihilations at 4.03 GeV

A search is performed for the production of the $\psi \mathrm{}\left(2S\right)\mathrm{}$ 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 $\psi \mathrm{}\left(2S\right)\mathrm{}$ signal are consistent with its being produced only in association with an energetic photon resulting from initial state radiation (ISR). Limits are placed on $\psi \mathrm{}\left(2S\right)\mathrm{}$ 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 $\psi \mathrm{}\left(2S\right)\mathrm{}$ production is due entirely to ISR, the partial width ${\Gamma }_{\mathrm{ee}}$ of the $\psi \mathrm{}\left(2S\right)\mathrm{}$ is measured to be $2.07\pm 0.32\mathrm{keV}.$