Gluon generalized parton distributions and angular momentum in a light-cone spectator model
Chentao Tan, Zhun Lü
Abstract
We study the leading twist gluon generalized parton distributions 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 $\ensuremath{\xi}=0$ in the overlap representation. The numerical results of the ${H}^{g}$, ${E}^{g}$, ${\stackrel{\texttildelow{}}{H}}^{g}$, ${H}_{T}^{g}$, and ${E}_{T}^{g}$ as functions of $x$ at different ${\mathrm{\ensuremath{\Delta}}}_{T}$ are presented. Particularly, ${H}^{g}$, ${\stackrel{\texttildelow{}}{H}}^{g}$ at nonzero ${\mathrm{\ensuremath{\Delta}}}_{T}$ 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 are considered. The kinetic orbital angular momentum is also calculated and is negative in our model.