Hard Diffraction in Pythia 8

TL;DR

This paper reviews and introduces models for diffraction in Pythia 8, including a new hard diffraction model that integrates with MPI, enabling more accurate simulations of diffractive events with gap survival effects.

Contribution

It presents a new hard diffraction model within Pythia 8 that incorporates dynamical gap survival probability, advancing the simulation of diffractive processes.

Findings

Existing soft diffraction model reviewed

New hard diffraction model implemented in Pythia 8

Model includes dynamical gap survival probability

Abstract

We present an overview of the options for diffraction implemented in the general-purpose event generator Pythia 8. We review the existing model for soft diffraction and present a new model for hard diffraction. Both models use the Pomeron approach pioneered by Ingelman and Schlein, factorising the diffractive cross section into a Pomeron flux and a Pomeron PDF, with several choices for both implemented in Pythia 8. The model of hard diffraction is implemented as a part of the multiparton interactions (MPI) framework, thus introducing a dynamical gap survival probability that explicitly breaks factorisation.