Helicity-dependent Twist-two and Twist-three Generalized Parton Distributions in Light-Front QCD

We investigate the helicity dependent twist-two and twist-three generalized parton distributions in light-front Hamiltonian QCD for a massive dressed quark target. Working in the kinematical region ξ < x < 1, we obtain the splitting functions for the evolutions of twist-two quark and gluon distributions in a straightforward way. For the twist-three distribution, we find that all contributions are proportional to the quark mass and thus the twist-three distribution is directly related to the chiral symmetry breaking dynamics in light-front QCD. We also show that the off-forward Wandzura-Wilczek relation is violated in perturbative QCD for a massive dressed quark.We calculate the quark mass correction to the WW relation in the off-forward case and show that it is related to h1(x) in the forward limit. We extract the ’genuine twist three’ part of the matrix element in the forward case and verify the Burkhardt-Cottingham and Efremov-Leader-Teryaev sum rules.