Parton shower algorithm with saturation effect

TL;DR

This paper extends a small x parton shower algorithm to include kinematic constraints and k_t resummation, enabling more accurate Monte Carlo simulations of processes with multiple hard scales in the saturation regime.

Contribution

It introduces a novel extension of the small x parton shower algorithm to incorporate kinematic constraints and k_t resummation effects, allowing simultaneous resummation of large k_t and small x logarithms.

Findings

First Monte Carlo implementation with combined resummation

Improved simulation accuracy in saturation regime

Potential applications to eA collision processes

Abstract

We extend the previously developed small $x$ parton shower algorithm to include the kinematic constraint effect and $k_t$ resummation effect. This work enables the Monte Carlo generator to simultaneously resum large $k_t$ and small $x$ logarithms in the saturation regime for the first time. It is an important step towards simulating processes involving multiple well separated hard scales, such as di-jet production in eA collisions at EIC.