Inelastic electroproduction of ηc at ep colliders

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Using the nonrelativistic QCD factorization formalism, we calculate the electroproduction cross sections of ηc in ep collisions, including the contribution from both the transverse photon and the longitudinal photon. For this process the color-singlet contribution vanishes up to the next to leading order perturbative QCD calculations. The dominant contribution comes from the color-octet ¹S₀⁽⁸⁾ subprocess. The nonperturbative color-octet matrix element of ¹S₀⁽⁸⁾ of ηc is related to that of ³S₁⁽⁸⁾ of J/ψ by heavy quark spin symmetry, and the latter can be determined from the direct production of J/ψ at large transverse momentum at the Fermilab Tevatron. The measurement of this process at DESY HERA can be viewed as another independent test for the color-octet production mechanism