Quark models and meson cloud in deep inelastic scattering

We propose a quark model description of the nucleon which includes, in a unified picture, valence quarks and a core of q (q) over bar pairs and gluons at the hadronic (non-perturbative) scale, The resulting parton distributions are evolved to high Q(2) by means of an appropriate next-to-leading order evolution and compared with the data, The procedure is carried out for several, rather different, quark model pictures to analyze the model dependence, We conclude that there is not a smooth transition between the degrees of freedom of low-energy nuclear physics (baryons and mesons) and a description in terms of quarks and gluons, (C) 1998 Elsevier Science B.V.