Implications of 'Event target could not be reached'
Hello,
I created my own model, which is basically SM + a scalar mediator, which can decay into electron neutrinos. With this model, I try to generate events of the form
med > e+ e- ve ve~
which can happen, if one of the final-state neutrinos radiates off a Z boson. I do this, because I need to know the energy distribution of the resulting electrons, i.e. d\Gamma/dE_e.
Now, my problem is as follows:
When I try to generate 10'000 events, this event target is always reached. However, when I try to generate 100'000 events, I oftentimes only get ~70'000 events and the message that the 'Event target could not be reached'. However, the result for the total width is always the same within the errors.
From other questions I know that this happens if there is a problem with the Monte-Carlo integration. For example, this also happens with the process z > e+ e- \gamma, which is divergent at LO. However, I am pretty sure that my process is not divergent, since the radiated Z boson is massive (The mediator has a mass of O(100GeV), i.e. Z cannot be considered massless). Also, I am really confused that I can generate 10*10'000 events, but not 1*100'000 events.
So my question is, can I still trust the resulting energy distribution, or is it likely that the Monte-Carlo integrator gets a wrong result due to the difficulties? Am I save if I just generate 10'000 events instead of 100'000 events? And why does this make a difference in the first place? And if I want to have N events, but only get M, do I have to correct the width by a factor M/N?
Thanks a lot for your help!
Best regards,
Marco
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