Sivers effect in Inelastic $J/ψ$ Photoproduction in $ep^\uparrow$ Collision in Color Octet Model

Paper

Abstract

The prediction of single-spin asymmetry in inelastic photoproduction of

collision is presented. At next-to-leading order, the dominating process is photon-gluon fusion,

for the production of

, which directly probes the gluon Sivers function. Using the non-relativistic QCD based color octet model, the color octet states

and

contribution to

production is calculated. Sizable asymmetry is estimated as a function of transverse momentum

and energy fraction

in the range

GeV and

. The unpolarized differential cross section of inelastic

photoproduction is found to be in good agreement with H1 and ZEUS data.