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Hi Heiko, we still need to make things work on MC, we hope to complete this today (sulle ali dell'entusiasmo...). Should we report at the SL meeting? I can prepare something, but I am not sure I will be able to show up at the meeting, last night has been very long ;-) W l'Italia! Concezio. Il giorno lun, 10-07-2006 alle 10:00 +0200, Heiko Lacker ha scritto: > Hi Concezio, > > first of all: congratulations to the new world champion! > > Second: Very good progress! > This looks like a real step forward. > > Cheers, > Heiko > > > On Fri, 7 Jul 2006, Concezio Bozzi wrote: > > > Hi, > > here are some results for the double ratio > > > > (signal/peakingBG)_MCenriched > > ----------------------------- > > (signal/peakingBG)_MCdepleted > > > > > > as a function of mx. We use this double ratio, multiplied by the ratio > > (signal/peakingBG) in the depleted data sample, in order to fix the > > (signal/peakingBG) components in the mES fits on data after all cuts as > > a function of mx. > > > > The various signal (S) and peakingBG (P) components of this double ratio > > on MC can be computed on either: > > > > (1) the entire MC sample, by performing a 3-parameter fit to S, P and > > combinatorialBG (B) > > > > or > > > > (2) on separate "signal" (reconstructed Breco mode == true Breco mode) > > and "background" (reconstructed Breco mode != true Breco mode) samples. > > In this case, the signal sample is used to determine S, whereas the > > background sample is used to determine P and B. > > > > Method (2) has a number of advantages on method (1): > > - the uncertainty on S and P is smaller > > - the bias on S is reduced, since we don't risk to mix up/swap signal > > and peaking background due to the very similar functional forms of their > > PDFs. > > > > The spreadsheet attached to this message proves the above two > > statements. > Excellent! > > > The upper part of the spreadsheet contains the results obtained with > > method (1), the lower part refers to method (2). Look e.g. at the > > errors on the peaking background numbers on the enriched sample on > > column E5-E14 for method (1) and E18-E27 for method (2). The same is > > true on the depleted sample (column Q) and for the signal yields > > (columns K and W). > > > > The bias in method (1) on the number of fitted signal and background > > events (columns I5-I14, U5-U14 for signal, AH5-AH14, AI5-AI14 for > > background) is also evident by comparing them to the number of expected > > events in the datasets (respectively: columns AI18-AI27, AI31-AI40 for > > signal, AH18-AH27, AH31-AH40 for background). > > > > The double ratios which come out are flat as a function of mx and are > > compatible with 1, see the light blue cells in the spreadsheet, or the > > attached eps file (The number for the last bin in mx is not meaningful > > since there are very few events in the mES plot). > > > > The bottom line is that the signal/peaking background in the mES fitss > > can be fixed in our data to the values which we obtain on the depleted > > sample, times a MC correction which turns to be about 1 within 10% and a > > ~10% uncertainty, which gets higher at high mx. > > > > This is not the end of the story, of course. The study needs to be > > repeated on the MC samples which we use in VVF (vcb+other, vubIN, > > voubOUT), since we have to fix the signal/peaking background components > > in there as well... > > > > Stay tuned, Antonio&Concezio. > >