SMASH HepMC output is an implementation of the HepMC3 Event Record Library. The aim is to provide a format compatible with other frameworks like Rivet (https://rivet.hepforge.org). For resources regarding HepMC, see http://hepmc.web.cern.ch/hepmc/ and https://arxiv.org/abs/1912.08005.

Producing HepMC output requires HepMC3 to be installed. Download the tarball from http://hepmc.web.cern.ch/hepmc/.

ASCII HepMC Format

HepMC generaly structures each event into particles and vertices connecting them, basically storing a graph of the event. Since the purpose of this output is to only provide a particle list of the final state produced the output format is adapted accordingly for the SMASH implementation: Only one central vertex is used. All intial state particles are incoming particles and all final state particles are outgoing particles of this vertex. Scatterings happening during the SMASH event are not recorded. For the collider modus, the intial state particles are combined into two single colliding nucleus "particles" with a nuclear pdg code.

The output is written in Asciiv3, the HepMC3 native plain text format. See https://arxiv.org/abs/1912.08005 for documentation of the format.

Note

Since some HepMC readers (e.g. Rivet) need a value for the nuclei-nuclei cross section, a dummy cross section of 1.0 is written to the output. Furthermore, if you use Fermi motion and want to read in the HepMC ouput into Rivet, you need to disable the check for the beam particle energies with the –ignore-beams option.