Monte Carlo and large angle gluon radiation

TL;DR

This paper examines the challenges of including recoil effects in Monte Carlo simulations of QCD evolution, highlighting conflicts with collinear factorization and the DGLAP equation.

Contribution

It identifies limitations of current dipole-based schemes in accurately modeling recoil effects and their impact on QCD evolution equations.

Findings

Recoil effects complicate dipole-based QCD simulations.

Simple recoil incorporation schemes conflict with collinear factorization.

Current methods do not reproduce the DGLAP equation accurately.

Abstract

We discuss the problem of incorporating recoil effects into the probabilistic QCD evolution scheme based on the picture of colour dipoles as done in recent Monte Carlo programs. Such a scheme correctly describes subleading soft contributions to multiplicity distributions. However we find that a simple receipt for incorporating recoil effects into the dipole multiplication picture conflicts the collinear factorization and does not lead to the correct DGLAP equation.