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given we are just taking X to be the sum of the four momemta we can just add covariance matrices. What is your perplexity? ciao ric ______________________________________________________ Riccardo Faccini U.C. San Diego, Universita' "La Sapienza" & I.N.F.N. Roma tel +39/06/49914338 http://www.slac.stanford.edu/~rfaccini Univ. La Sapienza. 2,Ple Aldo Moro, I-00100 Roma Dipartimento di Fisica "A voice said to me: 'smile and be happy, things could be worse'. I smiled and was happy and indeed things got worse" (an office in Ferrara) On Tue, 6 Nov 2001, Oliver Buchmueller wrote: > > Correct, so far I am using an "overall cov matrix" > for the event. However, technically the usage of event-by-event errors > is foreseen and (hopefully) it should improve things even further > - but not yet sure how to apply the event-by-event > stuff to the X-system ... a bit more brain power has to go into > this ..thought - > > Oliver > > > On Tue, 6 Nov 2001, Riccardo Faccini wrote: > > > Great! > > If I understand correctly you have not yet exploited the candidate by > > candidate information which is now in the ntuple, that could improve the > > situation (in particular the tails), correct? > > > > I will read the document more carefully later. > > thanks > > ric > > ______________________________________________________ > > Riccardo Faccini > > U.C. San Diego, Universita' "La Sapienza" & I.N.F.N. Roma > > tel +39/06/49914338 http://www.slac.stanford.edu/~rfaccini > > Univ. La Sapienza. 2,Ple Aldo Moro, I-00100 Roma > > Dipartimento di Fisica > > > > "A voice said to me: 'smile and be happy, things could be worse'. I smiled > > and was happy and indeed things got worse" (an office in Ferrara) > > > > > > > > On Tue, 6 Nov 2001, Oliver Buchmueller wrote: > > > > > > > > Dear All, > > > > > > as promised, the technical development of a > > > kinematic fit for semileptonic B events is > > > now finalized. All technical aspects have been > > > tested successfully (e.g. zero mass for neutrino, > > > overall constraint fullfillment,...). > > > The fit uses the whole event information including > > > not only the leptonic B decay but also the fully > > > reconstructed B candidate on the "other side". > > > Hence, not only energy momentum conservation but > > > also additional mass constraints like Equal Mass > > > or B Mass hypothesis can be used. > > > > > > For those who might be interested in details, > > > I have made a short node describing the technical > > > and physical aspects of this tool. Some performance > > > test are also shown in this note. > > > > > > The note can be found in: > > > http://www.slac.stanford.edu/~buchmuel/B-xlv_kinfit.ps > > > > > > This test indicates that's variables build out of > > > information from X-system AND neutrino (missing momentum) > > > are the most promising once in terms of "resolution improvements". > > > The results also suggest that more work has to > > > invested in the improvement of the X-system reconstruction > > > because it seems to be the limiting part in the > > > kinematic reconstruction. > > > > > > > > > I am looking forward to see your reaction/remarks/comments. > > > > > > Cheers, > > > > > > Oliver > > > > > > > > > By the way, > > > > > > this is clearly not the final word concerning kinematic fitting > > > of the semileptonic events ... it more supposed to be a start ...! > > > > > > > > > > > > > > > > > >