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Hi all, these are the results for the B decays and D decays systematics. I performed them both on data (blind) and on MC. Three shapes fit is on. I applied the technique and the code described by Alessio in the useful reference: http://www.slac.stanford.edu/~asarti/recoil/sys MC (fit on mixture cocktail-generic + vub signal) -- in the plots http://www.slac.stanford.edu/~daniele/vub/BDsystMCplot.eps you can find the distribution for the fitted BRBR including both B decays and D decays BR's reweighting and smearing. The default value (no correction) is 0.0180. The shift is -4.4%. The systematics is of the order of 10%. DATA ---- For the data I perform a bit more detailed study, studying B and D systematics separately. Here the default value is BRBR = 0.0198 +-0.034 (blind, no reweighting). In the ps file http://www.slac.stanford.edu/~daniele/vub/BDsystplots.ps you find - page 1 BRBR distributions for B decays syst. only (upper left), D decays syst. (upper right), both (bottom left). - page 2 distribution for mean, sigma and relative error for the three systematics separately. The shift is -3.4%/ The total systematics is ~7.7%. The MC and the data systematics can be different because this systematics is related to the bkg and it depends on the S/B for MX<MXcut and then on the final fitted ratio of BR's. DATA MX CUT STUDY ----------------- Since we want to decide the final value for Mx cut (see my previous posting), this systematics has to be studied with many cuts on Mx. (and then we will choose the mx cut that minimizes the total error = stat + syst + theo.). Look at http://www.slac.stanford.edu/~daniele/vub/mxstudy.ps In the first and second pages you find the distributions of BRBR for different Mx cuts and their spread (absolute and relative). The most important plot is the one on page 3. Here you can see the distribution of the systematic error (absolute) as a function of a cut on Mx with a p1 fit superimposed. Daniele