Polarized parton distributions and light-front dynamics

We present a consistent calculation of the structure functions within a lig ht-front constituent quark model of the nucleon. Relativistic effects and t he relevance of the covariance constraints are analyzed for both polarized and unpolarized parton distributions. Various models, which differ in their gluonic structure at the hadronic scale, are investigated. The results of the full covariant calculation are compared with those of a nonrelativistic approximation to show the structure and magnitude of the differences. (C) 1999 Elsevier Science B.V. All rights reserved.