Gluon parton density in the chiral quark model

Abstract

Dynamical chiral symmetry breaking is one of the most important properties of low energy QCD. The breaking pattern has a profound impact on phenomenological quantities. Here we extend the idea of the meson cloud approach in the chiral quark model to include a gluon cloud in order to model the parton densities in the nucleon, based on the constituent quark framework. To obtain parton densities, including the gluon density in the constituent quark approach , we use the splitting functions of a quark to quark-meson and quark-gluon at low Q 2 values. The parton densities at high energies can be obtained, using the DGLAP evolution equations. A good agreement with that expected is computed for the fraction of the total momentum of the proton which is carried by gluon. The chiral quark model (χQM) is used to study the flavor structure of the constituents quark and the nucleon within the conventional mesonic cloud picture. Using this model, the effects of SU (3) f symmetry breaking can be discussed . The implications of the Gottfired sum rule (GSR) violation on the Δ-n mass splitting is also considered. At a low-resolution scale energy the constituent quark picture is successfully described hadron structure function. The sea quark and gluon degrees of freedom are assumed to be absorbed into constituent quarks as quasi-particles [1, 2]. A relation between the two regimes of hadron structure function description; i.e. the chiral quark and the constituent quark models, has a considerable significance which has been investigated widely in literature, and attracts much more attention in recent years [3].