Semi-inclusive structure functions in the spectator model

We establish the relationship between distribution and fragmentation functions and the structure functions appearing in the cross-section of polarized 1-particle inclusive deep-inelastic scattering. We present spectator model evaluations of these structure functions focusing on the case of an outgoing spin-1/2 baryon. Distribution functions obtained in the spectator model are known to fairly agree at low-energy scales with global parameterizations extracted from totally inclusive DIS data. Therefore, we expect it to give good hints on the functional dependence of the structure functions on the scaling variables xB, z and on the transverse momentum of the observed outgoing hadron, Phperpendicularto. Presently, this dependence is not very well known, but experiments are planned in the near future. (orig.)