DISKinematics fails if photon virtuality is zero
The new formula for Y in the DISKinematics is ill-defined if the photon virtuality, _theQ2
, and therefore _theX
, is zero. Rivet will not crash but in fact not produce any error message and simply not write out any events. However, the old formula works fine, events are correctly processed.
This is relevant for the Sherpa event generator, as there the photons in the EPA approximation are real.
I guess, a possible fix would be to check whether _theQ2 == 0
and use the old formula in that case?