Event filter/selector on hadron level

[Frank Siegert]

Currently one can only cut events on the ME level and typically all hadron level cuts are applied in the analysis. Recently we have had a few cases where users thought it would be useful to apply selectors on the hadron level e.g. to reduce the size of files written out or to send only relevant events through full-sim.

This should be relatively simple with some kind of combination of the Analysis module with its Triggers and the output modules.

[Frank Siegert]

Implemented in r15493 and attached here as a patch for version 1.2.2:

  cd SHERPA-MC-1.2.2
  patch -p0 < event-selector.patch
  make install

It implements a pseudo-observable in the internal analysis module, which writes out events if the specified InList is not empty. This can be achieved using arbitrary combinations of analysis triggers. The event format can be specified exactly like the global event output. An example which will only write out events if the final state contains an electron:

(analysis){
  BEGIN_ANALYSIS {

  LEVEL Hadron;

  Trigger {
    InList   FinalState;
    OutList  Triggered;
    Counts   11    1  -1;
  }

  Event_Output {
    InList Triggered
    HEPMC2_GENEVENT_OUTPUT testfile
    FILE_SIZE 100
    EVT_FILE_PATH triggeredevents
  }
}(analysis)

As demonstrated, the Event_Output observable takes as arguments the name of the trigger list and additionally allows for all event output parameters as documented in the manual.

This should be used in an analysis with LEVEL Hadron only.

[Stefan Hoeche]

Milestone old deleted