Single spin asymmetries in a two components model

We study the spin asymmetries of inclusive π+,π0, π− and η production in the interaction of polarized with non polarized protons, in the frame of a two components model. Particle production in the model is assumed to consist of conventional fragmentation plus recombination. We obtain a good description of experimental data. Thomas precession in the recombination process seems to be responsible for the single spin asymmetry.