Twist-3 gluon GPDs for the nucleon in a spectator model

Abstract

We investigate the complete set of twist-3 gluon generalized parton distributions (GPDs) of the nucleon at nonzero skewness within a spectator model, in which the nucleon is treated as a two-body system consisting of an active spin-1 gluon and a spin-1/2 spectator particle. The spectator mass is allowed to vary continuously and is described by a spectral function, while the nucleon-gluon-spectator coupling is modeled by an effective vertex containing two form factors. We calculate the twist-3 gluon GPDs over a broad kinematic range and investigate the corresponding impact-parameter-dependent parton distributions, defined as two-dimensional Fourier transforms of the GPDs at zero skewness. In the forward limit, we further obtain the corresponding twist-3 parton distribution functions (PDFs). Our results provide model predictions for twist-3 gluon GPDs and PDFs that can be useful for future phenomenological studies and for investigating observables at current and future collider facilities.