A model for baryon production in spin-dependent string fragmentation

TL;DR

This paper extends the string+${}^3P_0$ model to include spin-1/2 baryons as quark-diquark states, predicting baryon polarization effects and enabling Monte Carlo simulations of baryon production.

Contribution

It introduces a novel approach to baryon production in the string fragmentation model, incorporating diquark states and polarization effects.

Findings

Predicted Collins effect for baryons from polarized quark fragmentation

Found spontaneous transverse polarization of produced baryons

Model suitable for Monte Carlo implementation

Abstract

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.