"PYTHIA and JETSET are programs 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. Together they contain theory and models for a number of physics aspects, including hard and soft interactions, parton distributions, initial and final state parton showers, multiple interactions, fragmentation and decay. They are largely based on original research, but also borrow many formulae and other knowledge from the literature."

The installation requires the libPythia6.so library. Then user should you the TPythia6 class.

1. You will only need a fortran compiler (g77).
2. Download the tarball for building the libPythia6 library.
3. Unpack it :

   tar zxf pythia6.tar.gz

4. Build the package using the corresponding make script (makePythia6.linux for instance)
5. Compile ROOT from sources :

   ./configure linux --enable-pythia6 --with-pythia6-libdir=/usr/bin/pythia6/pythia6

6. Put libPythia6.so in $ROOTSYS/lib and make the root installation !

• Pythia web site
• TPythia6 class