Gluon generalized parton distributions and angular momentum in a light-cone spectator model

Abstract

We study the leading twist gluon generalized parton distributions (GPDs) and the gluon angular momentum inside the proton within a light-cone spectator model. Using the light-cone wave functions derived from the model, we provide the expressions of these distributions at the particular kinematical point $\xi =0$ in the overlap representation. The numerical results of the $H^g$, $E^g$, ${\tilde{H}}^g$, $H_T^g$ and $E_T^g$ as functions of $x$ at different ${\Delta }_T$ are presented. Particularly, $H^g$, ${\tilde{H}}^g$ at non-zero ${\Delta }_T$ are different from their forward counterparts, the unpolarized distribution $f_1^g$ and the helicity distribution $g_1^g$, respectively. We also obtain the total angular momentum of the gluon contributed to the proton spin $J^g=0.19$, which is consistent with the recent lattice calculation after the uncertainties is considered. The kinetic orbital angular momentum is also calculated and is negative in our model.

Comments: typos corrected, references added