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Hi David, Vera, and Marcello, thanks a lot for your inputs. In the meantime, we have implemented the form factor weights for B->Dlnu, B->D**lnu and the B->Xulnu channels. None of these changes our results in any significant way (as expected). I added the results for the newest fit with taking the weight for the D** component from the fit to the depleted spectrum to the bottom of here: http://costard.lbl.gov/~kerstin/vubunf/r22/spectrum/spectrum.html To answer Vera's comment on using the B->D*lnu BF from the Breco sample: We do see a significantly better fit for the depleted spectrum if we use the higher B->D*lnu BF that we used for the analysis on release 18. The numbers and plots are on the same webpage (with the heading "B->Xclnu BF Reweighting According to What We Used on 18"). So I think the effect of this is basically achieved with the extra weight for the D**. It seems more-or-less a matter of taste which of the options we choose -- get a scaling for the D** or find a justification for using a higher D* BF. Thanks again, Kerstin On Thu, 17 Dec 2009, Marcello Rotondo wrote: > > > Hi all, > > I want just add my thought about the scaling we need to apply to the D* or > D** component to get a good chi2 in the final fit. > The fact that fitting the depleted sample with the D* free, we need to > rescale the D* up by a large amount, does not means we are measuring a larger > B->D*. > > As shown at the Coll. Meeting, fitting the Depleted sample with the D** free, > you get also un "unreasonble result" because the fit prefer to reduce the D** > fraction by ~30% when you know there are missing components. But also in this > case we are going in the same direction: the D* have to increased. (I have to > say here that I agree with kersint and I would prefer to fit the D**). > > But I want to remind you that in the fit on the Enriched sample (to extract > Vub) we have the total Vcb component free in the fit. The fit on the Depleted > say that the shape need to be adjusted, and the relative fraction of the > D*/D** have to be increased to get a good chi2. Otherwise the chi2 are bad. > That all we can say without other inputs. > > Cheers, > Marcello > > > > > On Fri, 11 Dec 2009, Luth, Vera G. wrote: > >> Hello Kerstin, >> >> sorry for the delay in response. >> I am somewhat hesitant to offer advice, since I am not >> directly involved. >> >> Here is my 5c of contribution to the discussion: >> >> Clearly your rescaling of the D* rate is unreasonable. >> I would fix the Dln, since this BF appears to be solid >> and should not be rescaled. >> The idea of rescaling the D* is based on the notion that it is the >> largest contribution and its BF is poorly known. So, if you scale D* up >> do you downscale down scale D**?? >> Another approach is to fix the D*ln to the BF measured with the BABAR >> Breco samples. But then how do you fill the rest of the BF? >> DO we just leave a gap? the appears to be difficult to accept, >> but may give better results! >> >> Without definite measurements we really are in trouble! >> >> I am afraid, these are very useful comments. Nothing you do not know! >> >> Ciao >> Vera >> >> >> >> ============================================ >> Vera Luth >> SLAC - Stanford University >> 2575 Sandhill Road, Menlo Park, CA 94025 >> Phone: 650 926 2702 FAX 650 926 2657 >> ============================================ >> >> -----Original Message----- >> From: Kerstin Tackmann [mailto:[log in to unmask]] >> Sent: Friday, December 11, 2009 8:51 AM >> To: vub-recoil; Lopes Pegna, David; Luth, Vera G. >> Subject: Re: Analysis status >> >> >> Dear all, >> >> should we interpret the silence as that there are no objections to what >> we >> are saying/proposing? >> >> Best, >> Kerstin >> >> On Tue, 8 Dec 2009, Kerstin Tackmann wrote: >> >>> >>> Dear vub-recoilers, conveners, Vera, >>> >>> we have continued to look into the things we showed at the CM last >> month and >>> are getting to a point where we would appreciate feedback on several >> points. >>> It would be nice for us to have these clarified before we move on to >> produce >>> a measured spectrum with complete systematics, which we will need to >> then >>> tune the unfolding. I am hoping that settling on a strategy now that >> is >>> supported by the AWG might spare us duplicating work. >>> >>> (1) >>> Is the fitting of a scaling factor for the D** component from the >> depleted >>> sample a strategy we are happy enough with? I did try rescaling the D* >>> (see the Nov 10 entry here: >>> http://costard.lbl.gov/~kerstin/vubunf/r22/spectrum/spectrum.html), >> but given >>> that supposedly we know the D* better (forgetting about the spread in >> the >>> different results...) I think I have some preference for >>> rescaling the D**, for which our knowledge is more limited. >>> >>> (2) >>> We evaluated another set of systematics to see what the discrepancy >> between >>> the fit results for the B->Xclnu scaling factor is that we fit on the >>> signal-enriched and -depleted samples. We go down from 5.5 sigma (stat >> only) >>> to 2.3 sigma including a good number of systematics. This page >>> http://costard.lbl.gov/~kerstin/vubunf/r22/spectrum/spectrum.html >>> has results from a lot of the studies we performed. I am also >> attaching a >>> slide that shows the breakdown of the systematics on the scaling >> factor >>> difference. If we cannot go ahead with this at this stage, I would >> appreciate >>> suggestions for what other studies we should be providing. >>> >>> (3) >>> We are currently only using FF reweighting for B->D*lnu given that mX >> should >>> not be very sensitive to FFs. So the only sensitivity we have comes >> from the >>> El cut at 1GeV. In the r18 round of the analysis the uncertainties >> from the >>> B->D*lnu FF were so low that we did not even quote them. However, we'd >> rather >>> include additional reweightings now than later if there are strong >> opinions >>> that reweightings for other channels are necessary. >>> >>> Thanks, >>> Kerstin >> > > > +------------------------------------------------------+ > Marcello Rotondo > INFN Sezione di Padova, Dipartimento di Fisica > Via Marzolo, 8 > 35131 Padova - Italy > Tel : +390498277047 > Fax : +390498277102 > Email: [log in to unmask], [log in to unmask] > +------------------------------------------------------+ > >