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Hi Heiko, I saw that but I could not figure out the reason for this yet, sorry. I tried to. Kerstin On Mon, 17 Jan 2005, Heiko Lacker wrote: > Hi Kerstin, > > there is something I do not fully understand. > For set 2 the errors on the moments for mxhad > are smaller than those for set 1. > > Heiko > > On Sat, 15 Jan 2005, Kerstin Tackmann wrote: > > > > > Hi, > > > > this will be a little lengthy, but it I guess it is interesting for the > > decision about the kinematic fitter (for both the (mX) BRBR and the > > mX unfolding). > > > > I ran the VirVubFitter jobs on generic MC using the same genMC files for > > the generic MC and as data (as we said on Friday). This uses the ichep > > ntuples. You can find the VirVubFitter output in the following directory > > at SLAC: ~kerstin/scra. > > Taking the numbers from the results.dat for the fitted numbers of events > > in the first bin (0..1.55GeV) I find > > S/N(mxhadfit) = 1.04 > > S/N(mxhad) = 0.98 > > so the difference is a lot smaller than what Roberto saw on data if I > > remember correctly. Maybe someone could check my numbers to make > > sure I did not mess it up? > > > > > > Also I computed the moments for the unfolded spectra. Please find the > > tables in here: > > http://www.slac.stanford.edu:~/public_html/vubfit/moments_data.pdf > > The systematics evaluated are the same we had on Friday: > > statistical (on spectrum and detector matrix), multiplicity category > > reweighting, B->Xclnu BFs, exclusive D BFs, mb and a from Belle, B->Xulnu > > BFs (as done for ichep). > > > > The first four pages have tables for the uncorrected and the bias > > corrected moments as obtained on data for mxhad and mxhadfit. Comparing > > the uncertainties it looks like we see quite larger uncertainties on some > > of the moments using mxhad. This is coming mostly from the systematics > > (see the tables where the uncertainties are split up). I tried to figure > > out where this comes from. First having a little closer look at the error > > bars on the left plot on page 4 of VR011105.pdf from last Friday you can > > see that we have larger error bars for mxhad than for mhadfit, so this is > > consistent. > > The corresponding covariance matrices for the theo and the B->Xulnu > > branching fraction uncertainties on the MEASURED spectrum show somewhat > > larger uncertainties using mxhad than unsing mxhadfit. The difference is > > larger when comparing the covariance matrices on the UNFOLDED spectra and > > results in the larger uncertainties on the moments, which you see in the > > tables. This cannot be due to "bad toys", since the evaluation of these > > two uncertainties does not use toys. > > We also see enlarged uncertainties on some moments from the B->Xclnu and D > > branching fraction uncertainties when using mxhad. This does not seem to > > be due to "bad toys" either. I used 1/4 of the respective covariance > > matrices for tests and so not see a change in the relative size (bad toys > > would become less likely when using smaller covariance matrices). > > > > My current guess is that the worse resolution in mxhad is the reason for > > the enlarged uncertainties, but I am not sure how to make a meaningful > > test for this. > > What I tried is to just use the detector response matrix using mxhadfit > > when evaluating the B->Xclnu and D BF uncertainty for the mxhad spectrum > > and I see that the effect gets smaller. So this backs the guess at least. > > > > The following pages show the moments of the unfolded spectra using generic > > MC, first for the Set 1 and the Set2 for which we showed the plots on > > Friday and then for the case where we do not split up the MC sample but > > rather use the full sample for both genMC and as data. Please have a look > > and check if you think they are close enough for mxhadfit and mxhad. > > There does not seem to be enlarged uncertainties for mxhad with respect to > > mxhadfit, but these uncertainties are primarily statistical (and we do not > > see a big enlargement for the statistical uncertainties on the moments for > > the data either, compared to what we see for the systematics). > > > > I compared the theo and B->Xulnu BF systematic uncertainties on BRBR for > > mxhad and mxhadfit, but there I do not see a large difference: > > > > for mxhadfit: +8.2% -7.5% (theo) +- 6.5% (B->Xulnu) > > for mxhad : +8.6% -7.5% (theo) +- 6.6% (B->Xulnu) > > > > I assume someone has something set up to do the same for the B->Xclnu and > > D BFs since it was done for the summer results. I copied my results.dat > > files for this to ~kerstin/ebr/. There is also the file giving the > > corresponding mean value (mxhadcleo). > > > > With the Run1+2 statistics those systematics we evaluated for mxhad seem > > to be larger than the same ones for mxhadfit when looking at the moments > > (I also see this in the covariance matrices). > > > > At least for the theo and B->Xulnu BF systematics I do not see such a > > large difference for BRBR between mxhad and mxhadfit. Maybe someone should > > check the B->Xclnu and D BFs? > > > > Cheers, > > Kerstin > > > > >