Measurement of the γγ*→η_{c} transition form factor

We study the reaction e+e-→e+e-ηc, ηc→KSK±π∓ and obtain ηc mass and width values 2982.2±0.4±1.6  MeV/c2 and 31.7±1.2±0.8  MeV, respectively. We find Γ(ηc→γγ)B(ηc→KK̅ π)=0.374±0.009±0.031  keV, and measure the γγ*→ηc transition form factor in the momentum transfer range from 2 to 50  GeV2. The analysis is based on 469  fb-1 of integrated luminosity collected at PEP-II with the BABAR detector at e+e- center-of-mass energies near 10.6 GeV.