HepMC Interface

An interface to the HepMC [Dob01] standard event record format has been provided by M. Kirsanov. To use it, the relevant libraires need to be linked, as explained in the README file. Version 1 of the program requires that CLHEP is also linked, for the handling of four-vectors, while version 2 is standalone. This requires some adjustments in the interface code based on which version is going to be used. The (simple) procedure to translate PYTHIA 8 events into HepMC ones is illustrated in the main21.c, main22.c and main23.c main programs. At the core is a call to the
HepMC::I_Pythia8::fill_next_event( pythia.event, hepmcevt ) 
routine, which takes a PYTHIA event as input and returns a HepMC one.