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Hi Urs, thanks very very much for all your useful comments. As usual you're too kind valuating the talk :)) ... I've added few answer below. Thanks again for looking at the draft. Alessio ______________________________________________________ Alessio Sarti Universita' & I.N.F.N. Ferrara >>>I'm in Ferrara<<< tel +39-0532-974328 Ferrara roma +39-06-49914338 SLAC +001-650-926-2972 "... e a un Dio 'fatti il culo' non credere mai..." (F. De Andre') "He was turning over in his mind an intresting new concept in Thau-dimensional physics which unified time, space, magnetism, gravity and, for some reason, broccoli". (T. Pratchett: "Pyramids") On Tue, 20 May 2003, Urs Langenegger wrote: > > Hoi Alessio, > > very nice talk! Here are just a few nit-picking comments: > > p2: "model dep." not due to mb, a parameters, but rather due to shape > function parametrization. The parameters per se are HQET "theory" > parameters, not a model. But the specific form of SF > parametrization in deFazio/Neubert is a model. Which is THE reason > why we want to avoid a dependency on the SF. > I hope to have made it more clear in the new version. > p4: I would flip the x-y axes for the "correlation" plot, then it's > the same as other people use, e.g. in the canonical plot of > Bauer/Ligeti (Fig 1 of ph/0107074). I think in general this is > called a "Dalitz" plot, not a "correlation" plot. > Done > p5: I do not think that we need to go as high as 10 GeV2. In fact, IF > we want to put out a result as soon as possible with minimal > changes, I would argue that the q2 cut should be relatively low, > with higher mX cuts than what we have done so far. See e.g. table > I in ph/0107074. > > Why 10Gev2? > I've specified that there's nothing "magic" with that number and that is just a point of the scan as the others... > I have to admit that I have not yet clicked through all the links > in your webpage, I don't know whether you have done this. Ed has > produced scans in the (mX, Q2) plane. It would be very nice to have Ed posting those scans and take a look at the results :). Knowing that before I could even think about putting that material in the talk: there's anything providing Ed making that information public? > > p6: I think that this should be a 2-d scan in (mX,q2), not just a 1-d > scan. You must look at different combinations. > > Not only "sys" reduction, but "sys^2 + theo^2". We will not gain > in "sys" probably. I've fixed the notation: here sys = theo... As I've already told you I do not have a SCAN in mx,q2 plane. Just other few points at mx cut = 1.75... and situation is not improving. But maybe I have other problems... :) > > p7: Naive question: Why does the efficiency flatten at mX = 1.8GeV? > Applying a q2 > 10 GeV2 should leave signal rate to higher mX > (both from your plot on page 4 and from ph/0107074). > > Again, I think that it should be a 2-d scan of the error not only > vs. q2, but in the full (q2,mX) plane. > > p8: By now I think I was confusd and what you call "sys" is actually > "theo"; OK... > > p9: I would propose that we very seriously consider switching to the > non-resonant as "default" signal MC. Of course we need to > understand the behavior of the error on the hybrid MC. > > p10 I would feel (very) uncomfortable to extract mb from a spectrum > that shows a disagreement between the model and data as shown in > the bottom left two plots. > > Before we do that we should be sure that e.g. changing neutrals > selection and tracking has a very small effect on this. There is > work ongoing by Jonathan Coleman which we should look at. I > consider this one of the more important improvements (on a time > scale longer than this summer) for the incl b2u analyses. > The talk say at the end that this was just a First Look that needs further studies and can be promising: nothing more. I completely agree with your comments. > p12 Again, I personally would not claim that we can extract mb from > the mX distribution to 80MeV. > I'm not claiming that: I took the output from the chisquare scan, plotting it, taking the minimu, going up +1, matching the scan with the green line and calculating the (+1sigma - -1sigma)/2 value as error from chisq scan. This needs to validated against binning fro chi2, selection and so on and so forth..... That was just the output of "an eye analysis" to give a feeling of a possible resolution... > p18 "1." I would maybe say that we need to understand the hybrid MC > "For this summer 2." I would say we need to validate the spectra > other than mX given from the fit. > Done. Thanks again for the careful reading. A new version will be ready as soon as I finish to discuss more details with Daniele. Ciao, Alessio > That's all for now. > > Cheers, > --U. > >