Bound-state quark and gluon contributions to structure functions in QCD

Abstract

One can distinguish two types of contributions to the quark and gluon structure functions of hadrons in quantum chromodynamics: “intrinsic” contributions, which are due to the direct scattering on the bound-state constituents, and “extrinsic” contributions, which are derived from particles created in the collision. In this talk, I discuss several aspects of deep inelastic structure functions in which the bound-state structure of the proton plays a crucial role: (1) the properties of the intrinsic gluon distribution associated with the proton bound-state wavefunction; (2) the separation of the quark structure function of the proton into intrinsic “bound-valence” and extrinsic “non- valence” components which takes into account the Pauli principle; (3) the properties and identification of intrinsic heavy quark structure functions; and (4) a theory of shadowing and anti-shadowing of nuclear structure functions, directly related to quark-nucleon interactions and the gluon saturation phenomenon.