High-Energy-Physics Event Generation with PYTHIA 6.1

TL;DR

Pythia 6.1 expands a long-standing Monte Carlo event generator by integrating numerous SM and BSM subprocesses, refined QCD radiation, enhanced photon physics, and advanced hadronization and interconnection models. It introduces improved matrix-element and parton-shower matching, a sophisticated treatment of beam remnants and multiple interactions, and a revamped decay framework with broad applicability to current and future colliders. The paper documents substantial algorithmic and data-structure upgrades, new interfaces for external processes, and extensive parameterization options, aiming to deliver more realistic, experiment-ready event generation while signaling a shift toward a C++ successor (Pythia 7) for long-term development.

Abstract

PYTHIA version 6 represents a merger of the PYTHIA 5, JETSET 7 and SPYTHIA programs, with many improvements. It can be used to generate high-energy-physics `events', i.e. sets of outgoing particles produced in the interactions between two incoming particles. The objective is to provide as accurate as possible a representation of event properties in a wide range of reactions. The underlying physics is not understood well enough to give an exact description; the programs therefore contain a combination of analytical results and various models. The emphasis in this article is on new aspects, but a few words of general introduction are included. Further documentation is available on the web.