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Hi Urs, > Why is the B0 default value higher than what we had last week (BRBR = > 0.0279 +- 0.0049)? Now it seems to be very close to 0.03. > non res MC vs hybrid MC produces this difference > Why the variation by 150 MeV? I thought we had decided to use > something like 90 MeV? in order to see the impact of this effect I used a large shift > > The scans assume the default to be at 1.55, not your latest "optimal" > value of 1.63, right? yes but I just wanted to be consistent with the results of the last weeks > > > > As you can notice, moving mb down and a up, fixs part of the discrepancy > > at low Mx low values. > > I would not say this (i.e. I disagree). In the DATA scans, compared to > the default, the diff plots would indicate that the lower mb scans > have higher level of disagreement. The overall shape seems to be > independent of the mb value. The same seems to be true for mb = 4.95 > (again, from the diff plots). I would conclude from this that we > cannot measure mb competitively with this analysis. I fully disagree. Generic MC is able to reproduce part of the problem. If we are sensitive to this effect, we are able to measure it. If you are talking about the errors in the diff plots, I agree that the difference in quadrature is not optimal. We should finally figure out the way to compute them correctly. > > > 4) our measurement is so clean and we have so many events that we are > > sensitive to these theoretical parameters. We can start thinking about > > fitting a and mb. > > I think before we do that, we should understand the reco level cuts > and effects a bit better. > > > > 5) I am a bit less worried about this slope now > > I am a man of constant sorrow (as blind Richard Burnett would sing) ... I am short of ideas now. Our control samples work fine. Data-MC comparisons are ok (except the one on the variable we use to extract Vub) Bchs work fine (except some disagreement at low values but I think this is compatible with the theo systematics). either new ideas or let's assign a new systematics or let's demonstrate that what we are seeing is covered by the present systematics. Daniele