Supported file formats

PROMC file format is used since 2014. It is primary used to to keep EVGEN records (truth level). The format uses Google protocol buffers. It uses varints for integer values (and, by design, for 4-momenta and vertex). It's efficient format for events with large number of particles. The file sizes are typically 30% smaller than traditional ROOT with fixed bytes for floats and integer values.

PROIO file format is used since 2018. It is more efficient file format then ProMC when the number of events in the files larger than 64k, and when number of particles in files is not large.

ROOT files are used to keep fast detector simulations from Delphes

LCIO files are used to keep simulated and reconstructed events for Geant4 simulation (and reconstruction) using “all-silicon” detector deigns.

LHE file formats are typically used for parton-level events from Madgraph.