Recent program version: PYTHIA 8.1

With the release of PYTHIA 8.1, this new C++ version series took over from the older Fortran 77-based PYTHIA 6.4 one as the new standard. It was strongly recommended to move to PYTHIA 8.1 for LHC studies, although for practical reasons the transition was a slow one in the experimental community.

This initial PYTHIA 8.1 release is focussed towards LHC and Tevatron applications, i.e. high-energy p p and pbar p collisions. Also e+ e- and mu+ mu- annihilation processes may be simulated, but not e.g. e p, gamma p or gamma gamma collisions. This is the major exception where PYTHIA 6.4 still has more to offer. For the rest PYTHIA 8.1 offers many features not found in PYTHIA 6.4, which should make a transition worthwhile.

The release of PYTHIA 8.2 in October 2014 means that PYTHIA 8.1 will not be developed any further, and that bug fixes would result in a new 8.1 subversion only if there are special reasons for it. The main reason for this is that the step from the later 8.1 subversions to 8.2 is so small that we expect most users to take it rather quickly.


To get going with the program, do the following (on a Linux or Mac OS X system):


All necessary information how to run the program is available in subdirectories of the pythia8186 directory you unpacked above, and copies of them are also linked here. In addition, the complete PYTHIA 6.4 Physics and Manual is still relevant for most of the physics in 8.1. Also the manual parts may be helpful since many 8.1 settings have exact counterparts in 6.4, but finding them may be too time-consuming for the normal user.


Previous presentations

Related programs

Earlier versions

Normally there should be no reason now to install an older, obsolete version.
However, for backwards checks, this might be required, so here are the previous ones:

Working materiel

In this section is collected some of the internal documents used in preparing the code.

The updates of branching ratios to the 2012 Review of Particle Physics for