Dear Lorenzo,
thanks a lot for the explanation! I think I can proceed with the chi2 fit for now. On the long run, maybe doing an log Likelihood fit of the histgram I am subtracting plus the expontial to the first histogram might be more straight forward (as I found in the helpful post here using skellam as search word: Skellam distribution maximum likelihood fitter? ).
Just do be sure I understood correctly, if I am doing the “L” or “WL” fit option as I do now, this might lead to incorrect results?
Cheer,
Dorin