Orbital structure of quarks inside the nucleon in the light-cone diquark model

We study the orbital angular momentum structure of the quarks inside the proton. By employing the light-cone diquark model and the overlap representation formalism, we calculate the chiral-even generalized parton distribution functions H_q(x,ξ,Δ²), H∼_q(x,ξ,Δ²), and E_q(x,ξ,Δ²) at zero skewedness for q=u and d quarks. In our model, E_u and E_d have opposite sign with similar size. Those generalized parton distribution functions are applied to calculate the orbital angular momentum distributions, showing that L_u(x) is positive, while L_d(x) is consistent with zero compared with L_u(x). We introduce the impact parameter dependence of the quark orbital angular momentum distribution. It describes the position space distribution of the quark orbital angular momentum at given x. We found that the impact parameter dependence of the quark orbital angular momentum distribution is axially symmetric in the light-cone diquark model.