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Yes, lets discuss it on Monday! On Wed, 7 Nov 2001, Riccardo Faccini wrote: > Hi Oliver, > I have no doubt that your approach is valuable and I am happy to see it > carried on. I would spend one word on why it would be nice to have the > possibility to look at the other "biased" approach, though. > > To say it in simple words, I would like to be able (also) to apply the > neutrino mass constraint and look at the chi^2 for this fit. If you wish > it is just an hypothesis testing: "is it true that in this event we are > missing only a neutrino?" > > > > > So all missing momentum and energy from lost particles will be blamed > > on the neutrino and you naturally will get biased kinematic > > estimators. Even worse is the fact, that the chi^2 will not reflect > > this behavior because the neutrino, as unmeasured quantity, does not > > enter in the chi^2 definition -> You get a biased kinematic with > > a normal chi^2 behavior. No way to separate good from bad events. > > I would say that the chi^2 will reflect that there is a problem if the > neutrino mass constraint is imposed: you are just imposing a constraint > which does not apply. > If you wish this approach is the same as cutting on the Prob(chi2) of a > track fit or a vertex fit: if the background is due to tracks that do not > actually come from the same vertex ,cutting on the chi2 makes sense. > > This said I am happy with your approach, I am just suggesting one more > knob. We can discuss this by phone either offline (in particular if I am > misunderstanding what you say) or on monday. > > thanks > ric > >