Quark fragmentation functions in a diquark model for proton and $\Lambda$ hyperon production

A simple quark-diquark model for nucleon and $\Lambda$ structure is used to calculate leading twist light-cone fragmentation functions for a quark to inclusively decay into P or $\Lambda$. The parameters of the model are determined by fitting to the known deep-inelastic structure functions of the nucleon. When evolved from the initial to the final $Q^2$ scale, the calculated fragmentation functions are in remarkable agreement (for $z>0.4$) with those extracted from partially inclusive $ep$ and $e^+ e^-$ experiments at high energies. Predictions are made, using no additional parameters, for longitudinally and transversely polarized quarks to fragment into p or $\Lambda$.