Charmonium Production in Photon-Photon Collisions

We have searched for the two-photon production of the ηc, χ0, and χ2 charmonium states at the SLAC e+e- collider PEP in the channels γγ→K±KS0π∓, γγ→K+K-π+π-, γγ→π+π-π+π-, and γγ→K+K-K+K-. We identify four ηc candidates in the K+K-K+K- channel on a negligible background; the one φφ event among them implies a 95%-confidence-level (C.L.) lower limit for Γγγ(ηc) of 1.7 keV. In the other channels we find no evidence for any of the three states. We …