Sivers effect in inelastic J /ψ photoproduction in ep ↑ collision in color octet model

Abstract

The prediction of single-spin asymmetry in inelastic photoproduction of J/ψ in ep↑ collision is presented. At next-to-leading order, the dominating process is photon-gluon fusion, γ+g→J/ψ+g for the production of J/ψ in e+p↑→J/ψ+X, which directly probes the gluon Sivers function. Using the nonrelativistic QCD based color octet model, the color octet states S31(8), S10(8) and P3J(0,1,2)(8) contribution to J/ψ production is calculated. Sizable asymmetry is estimated as a function of transverse momentum PT and energy fraction z of J/ψ in the range 0