Recursive model for the fragmentation of polarized quarks

TL;DR

This paper introduces a recursive Monte Carlo model for polarized quark fragmentation based on string dynamics and the ${}^3P_0$ mechanism, successfully reproducing experimental spin asymmetry data.

Contribution

It presents a novel recursive model incorporating spin effects and the ${}^3P_0$ mechanism for simulating polarized quark fragmentation in jets.

Findings

Model reproduces SIDIS and $e^+e^-$ data on spin asymmetries.

Incorporates complex mass parameter to account for single spin asymmetries.

Predicts jet-handedness consistent with experimental observations.

Abstract

We present a model for Monte Carlo simulation of the fragmentation of a polarized quark. The model is based on string dynamics and the ${}^3P_0$ mechanism of quark pair creation at string breaking. The fragmentation is treated as a recursive process, where the splitting function of the subprocess $q \to h + q'$ depends on the spin density matrix of the quark $q$. The ${}^3P_0$ mechanism is parametrized by a complex mass parameter $\mu$, the imaginary part of which is responsible for single spin asymmetries. The model has been implemented in a Monte Carlo program to simulate jets made of pseudoscalar mesons. Results for single hadron and hadron pair transverse-spin asymmetries are found to be in agreement with experimental data from SIDIS and $e^+e^-$ annihilation. The model predictions on the jet-handedness are also discussed.