A parton branching algorithm with transverse momentum dependent splitting functions

TL;DR

This paper introduces a novel parton branching algorithm that incorporates transverse-momentum dependent splitting functions, enabling more accurate Monte Carlo simulations for high-energy physics, especially at small-x regimes.

Contribution

It presents the first implementation of a TMD-based parton branching algorithm with a new TMD Sudakov form factor, advancing Monte Carlo methods for parton distribution evolution.

Findings

First MC implementation of TMD splitting functions

Evaluation of small-x corrections to PDFs

Verification of momentum sum rule

Abstract

Parton branching methods underlie the Monte Carlo (MC) generators, being therefore of key importance for obtaining high energy physics predictions. We construct a new parton branching algorithm which for the first time incorporates the off-shell, transverse-momentum dependent (TMD) splitting functions, defined from the high-energy limit of partonic decay amplitudes. Based on these TMD splitting functions we construct a new TMD Sudakov form factor. We present the first MC implementation of the algorithm for the evolution of the TMD and integrated parton distribution functions (PDFs). We use this implementation to evaluate small-$x$ corrections to the distributions and to verify the momentum sum rule. The presented study is a first step towards a full TMD MC generator covering the small-$x$ phase space.