Toward simulation of quark and diquark fragmentations in the Quark-Gluon String Model (QGSM)

TL;DR

This paper improves Monte Carlo simulation methods for quark and diquark fragmentation functions within the Quark-Gluon String Model, aiming to better match experimental data, especially from NA61/SHINE.

Contribution

It proposes an enhanced Monte Carlo approach for simulating fragmentation functions, addressing limitations of previous simplified estimations.

Findings

Improved Monte Carlo simulation reproduces Kaidalov's fragmentation functions.

Enhanced models better fit experimental data from NA61/SHINE.

Method can be integrated into existing event generators like QGSM and Geant4.

Abstract

Within the Quark-Gluon String Model A.B. Kaidalov found a behaviour of quark and diquark fragmentation functions for $z\rightarrow 0$ and $z\rightarrow 1$, and proposed interpolation formulae for the functions in the whole region of $z$. These functions must be a solution of the well-known system of the integral equations. A simplified Monte Carlo estimation of the functions, based on usage of the fragmentation functions at $z\rightarrow 1$ as the kernel functions of the system, does not reproduce Kaidalov's results. An improvement of the Monte Carlo simulations is proposed in this paper. It can be implemented in Monte Carlo event generators such as Los Alamos QGSM, QGSJet-II and the Geant4 QGS model. It will improve a description of experimental data in the models, especially, the description of the latest NA61/SHINE Collaboration data on $\pi{\rm C}$ interactions. Description of the data is a problem in DPMJet, QGSJet, EPOS and Sibyll models.