Further experimental tests for simple relations between unpolarized and polarized quark parton distributions.

Some simple relations between unpolarized and polarized quark parton distributions have direct experimental consequences which will be presented here. In particular, we will see that it is possible to relate the deep inelastic structure functions F2 and g1, both for proton and deuteron, in fair agreement with experimental data. Key-Words : polarized parton densities, deep-inelastic scattering. Number of figures : 3 August 1995 CPT-95/P.3224 anonymous ftp or gopher: cpt.univ-mrs.fr ∗Unité Propre de Recherche 7061 Deep inelastic scattering of polarized electrons and muons off polarized targets have been used to study the internal structure of the nucleon. The most abundant and accurate experimental information we have so far, concerns the so called g1 spin structure function obtained with longitudinally polarized leptons on longitudinally polarized protons, deuterons and He targets [1, 2, 3, 4, 5] which allow to get separately g 1 for protons and g n 1 for neutrons. In the scaling limit, g1 is a function of only the well known Bjorken variable x = Q/2mpν, but when Q , the square of the four-momentum of the virtual photon of energy ν, is finite, g1 depends also on Q . So let us consider a situation with scaling violations and we recall that for protons one has g 1(x,Q ) = 1 2 [ 4 9 ∆u(x,Q) + 1 9 ∆d(x,Q) + 1 9 ∆s(x,Q) ]