A Brief Introduction to PYTHIA 8.1

TL;DR

PYTHIA 8.1 is a comprehensive C++ tool for simulating high-energy particle collisions, integrating advanced physics models and new features suitable for LHC research.

Contribution

It introduces a complete C++ rewrite of PYTHIA with new physics features, enhancing its capabilities for high-energy collision simulations.

Findings

First main release in C++ after Fortran version

Includes new physics aspects for LHC studies

Maintains core physics models with added utilities

Abstract

The PYTHIA program is a standard tool for the generation of high-energy collisions, comprising a coherent set of physics models for the evolution from a few-body hard process to a complex multihadronic final state. It contains a library of hard processes and models for initial- and final-state parton showers, multiple parton-parton interactions, beam remnants, string fragmentation and particle decays. It also has a set of utilities and interfaces to external programs. While previous versions were written in Fortran, PYTHIA 8 represents a complete rewrite in C++. The current release is the first main one after this transition, and does not yet in every respect replace the old code. It does contain some new physics aspects, on the other hand, that should make it an attractive option especially for LHC physics studies.