The HepMC C++ Monte Carlo event record for high energy physics

HepMC is an Object Oriented event record written in C++ for High Energy Phy sics Monte Carlo event generators. Many extensions from HEPEVT, the Fortran HEP standard, are supported: the number of entries is unlimited, spin dens ity matrices can be stored with each vertex, flow patterns (such as colour) can be stored and traced, random number generator states can be stored, an d an arbitrary number of event weights can be included. Particles and verti ces an stored separately in a graph structure, reflecting the evolution of a physics event. The added information supports the modularization of event generators. The event record has been kept as simple as possible with mini mal internal/external dependencies. Event information is accessed by means of iterators supplied with HepMC. (C) 2001 Elsevier Science B.V. All rights reserved.