Rivet tutorials

--ignore-beams flag

The --ignore-beams option disables the automatic beam-energy consistency check that normally occurs during the analysis initialisation phase.

Default behaviour

For most analysis routines corresponding to experimental measurements, the centre-of-mass energy is specified in the analysis .info file. During initialisation, Rivet checks the beam configuration in the input HepMC events against the allowed energies listed in the .info file.

If none of the allowed energies match, the analysis routine is disabled and will not run.

Behaviour with --ignore-beams

When --ignore-beams is supplied, this energy cross-check is skipped. This allows analyses to be executed even if the event sample’s beam energy does not exactly match the values listed in the .info file.

This can be useful, for example, when testing or validating analyses with Monte Carlo samples at slightly different energies.

[!caution] The --ignore-beams flag is only safe to use for analyses that correspond to a single centre-of-mass energy. For analyses covering multiple energies, Rivet cannot determine which subset of histograms should be filled. In such cases, use the ENERGY option (see below) to explicitly set which energy the analysis should assume.

Overriding beam energy

The ENERGY option can be used to force an analysis to assume a specific centre-of-mass energy, regardless of the actual beam configuration in the HepMC events. This option can be used, for example, to select which histograms are filled in analyses that include results for multiple energies.

Example usage:

rivet --ignore-beams -a ALICE_2010_I852264:ENERGY=7000 myevents.hepmc