Collins fragmentation function for pions and kaons in a spectator model

TL;DR

This paper models the Collins fragmentation function for pions and kaons using a spectator model, fitting parameters to data, and provides the first calculation for kaons, showing reasonable agreement with experimental parametrizations.

Contribution

It introduces a spectator model with pseudoscalar coupling to calculate the Collins function for both pions and kaons, including the first kaon computation.

Findings

The pion Collins function aligns with recent data-based parametrizations.

First calculation of the kaon Collins function within this model.

Model parameters successfully fit unpolarized fragmentation functions.

Abstract

We calculate the Collins fragmentation function in the framework of a spectator model with pseudoscalar pion-quark coupling and a Gaussian form factor at the vertex. We determine the model parameters by fitting the unpolarized fragmentation function for pions and kaons. We show that the Collins function for the pions in this model is in reasonable agreement with recent parametrizations obtained by fits of the available data. In addition, we compute for the first time the Collins function for the kaons.