Last Updated on June 18, 2026
PYTHIA is a program for the generation of high-energy physics events, i.e. for the description of collisions at high energies between elementary particles such as e+, e-, p and pbar in various combinations.
It contains theory and models for a number of physics aspects, including hard and soft interactions, parton distributions, initial- and final-state parton showers, multiparton interactions, fragmentation and decay. It also has a set of utilities and several interfaces to external programs.
It’s largely based on original research, but also borrows many formulae and other knowledge from the literature.
Main tasks performed by the program include the exploration of experimental consequences of theoretical models, the development of search strategies, the interpretation of experimental data, and the study of detector performance. Thereby it spans the whole lifetime of an experiment, from early design concepts for the detector to final presentation of data.
The software can simulate:
- Hard and soft interactions.
- Parton distributions.
- Initial/final-state parton showers.
- Multiple interactions.
- Fragmentation and decay.
Website: pythia.org
Support: Documentation, Introduction
Developer: Christian Bierlich, Nishita Desai, Ilkka Helenius , Philip Ilten, Leif Lonnblad, Stephen Mrenna, Stefan Prestel, Christine O. Rasmussen, Torbjorn Sjostrand, Peter Skands
License: GNU General Public License v2.0
PYTHIA is written in C++. Learn C++ with our recommended free books and free tutorials.
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