Production of ${\chi }_c$ in electron-positron colliding-beam experiments

The differential cross section for production of ${\chi }_c\left(1\mathrm{}{}_{}{}^1{}_{}{}^{}S_0^{}{}_{}{}^{}\right)$, an even-charge-conjugation state, in electron-positron colliding-beam experiments via the two-photon-exchange mechanism has been calculated. The results obtained in the one-equivalent-photon approximation are also mentioned for comparison. Structure effects have been estimated.