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The absolute value of USER_spectrum_mode determines which beamstrahlung spectrum is used, with the sign +/- indicating
electron/positron beam, respectively. For the 500 fb -1 SM data sample this absolute value is always 2, and corresponds
to the Guinea-Pig beamstrahlung data contained in the directory ftp://ftp-lcd.slac.stanford.edu/ilc/ILC500/StandardModel/guinea-pig/ilc_0500_may05_run05_seed06/
This spectrum represents the default ILC design for Ecm=500 GeV circa August 2005.
FAQ
Whizard has no gluon emission by default, leading to potentially incorrect multiplicity distributions.
This is true for WHIZARD but irrelevant for this sample since the parton showering was done with PYTHIA.
Whizard has an incorrect implementation of the CKM matrix. Only diagonal terms of the matrix are present (and = 1!), giving wrong W decays.
Although true, it is extremely doubtful that this will have any effect on the current analyses. When we regenerate these datasets, we will be using the latest version of Whizard, which has corrected this.
This sample has generator level cuts a la SiD, providing a potential bias when used for ILD.
There are, indeed, some kinematical cuts for processes with divergent cross-sections, which can be seen by looking at the whizard.in file as described above. However, the only kinematic cut that leads to a genuine loss of events is a 4 GeV minimum invariant mass cut on final state fermion-antifermion pairs.