Fermi-dirac Distributions for Quark Partons

We propose to use Fermi-Dirac distributions for quark and antiquark partons. It allows a fair description of the x-dependence of the very recent NMC data on the proton and neutron structure functions F p 2 (x) and F n 2 (x) at Q = 4 GeV, as well as the CCFR antiquark distribution xq(x). We show that one can also use a corresponding Bose-Einstein expression to describe consistently the gluon distribution. The Pauli exclusion principle, which has been identified to explain the flavor asymmetry of the light-quark sea of the proton, is advocated to guide us for making a simple construction of the polarized parton distributions. We predict the spin dependent structure functions g 1(x) and g n 1 (x) in good agreement with EMC and SLAC data. The quark distributions involve some parameters whose values support well the hypothesis that the violation of the quark parton model sum rules is a consequence of the Pauli principle. Number of figures : 6 October 1993 CPT-93/P.2961 anonymous ftp or gopher: cpt.univ-mrs.fr † Unité Propre de Recherche 7061 Dipartimento di Scienze Fisiche, Universitá di Napoli, Mostra d’Oltremare, Pad. 19, 80125 Napoli, Italy