Hi Antonio, can we also have a look at the plots for the MX fits, both for signal-enriched and signal-depleted? I'm curious, after all re-weightings discussed so far, how the fit performs above 2 GeV. Cheers, Heiko On Tue, 26 Sep 2006, Antonio Petrella wrote: > Hi, > on the web page where I posted results of systematics due to > randomization of S/P: > > http://www.slac.stanford.edu/~petrella/systsp.html > > you can see that this systematic error is not stable, for example when > cutting on integrated purtity. > > Now I'm trying to look at other results from these jobs to see if I can > find what makes this errors so large, but probably this is also due to > the S/P ratio and its error. > > For example if you look at the correction factors for IP > 0.50 > (http://www.slac.stanford.edu/~petrella/tmp/SP_allrew/SPallweights/ip050_allrew/corrallwip050pol1.eps) > > you can see that the first bin has a large error (the exact value of the > correction factor for this bin is S/P = 5.67 +- 5.34) > > These numbers (they're on the spreadsheet at > http://www.slac.stanford.edu/~petrella/tmp/SP_allrew/SPallweights/SoverPFullRew.sxc) > come from the double ratio of S/P on MC (0.74 +- 0.13) times the S/P > ratio on data depleted sample > > (http://www.slac.stanford.edu/~petrella/tmp/SP_allrew/SPallweights/ip050_allrew/data_depl_AC_intp0.50_0.001.55.eps) > > On data depleted sample the signal component (fitted) is 291 +- 31 and > the background component (fitted) is 38 +- 35, so the error on the final > S/P ratio is driven by the background component on data depleted > sample... and cutting on purity (and having less background) will give > roughly higher errors on background component (at least the statistical > error). > > For the data depleted sample we get S +- dS and P +- dP as they come out > from the fit and then we compute the quantity S/P +- d(S/P). But these > errors are correlated, aren't they? > > ciao, > Antonio >