η _c Diffractive Production in the Direct Photon Process

Abstract

Based on the factorization theorem for lepton induced hard diffractive scattering and color octet heavy quarkonium production mechanism, ηc diffractive production in the direct photon process is studied. The results show that this process can be measured at DESY HERA, and ηc production has different features from J/ψ production, which is weakly affected by the initial and final state gluon radiation. Therefore, ηc photoproduction can be viewed as reliable estimate. The experimental study of this process can give valuable insight in the color octet heavy quarkonium production mechanism.