A model for baryon production in spin-dependent string fragmentation

We introduce spin-1/2 baryons in the string+${}^3P_0$ model of hadronization, previously restricted to the production of pseudoscalar and vector mesons. Baryons are modeled as quark-diquark bound states and baryon production is described by the tunneling of diquark-antidiquark pairs at string breaking points. Diquarks can be scalar or pseudovector, the latter being produced in the relative ${}^5D_0$ state. Introducing the quark-baryon-diquark coupling, the relevant splitting amplitudes for the emission of baryons are constructed and used to explore analytically the model predictions. We find a Collins effect for baryon production in the fragmentations of transversely polarized quarks or diquarks as well as a baryon spontaneous transverse polarization. The hadronic decays of polarized hyperons are also included in the model, which is presented in a form suitable for the implementation in a Monte Carlo event generator.