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Ciao Alessio, if I understand correctly your page, there are two independent measurements of pilnu and rholnu. If one believes in isospin relationship one should have to average the two results (scaled to be measurement of the same thing) and quote this error. The error would be ~0.42, but it would be underestimated because of the fact that isospin relationships might not be exact. To account for this I suggest we take the error from a single measurement, basically treating them as uncorrelated. Since the rho has the smallest relative error 60/260, I would use this one and vary the exclusive B0 rate by 23% and the B+ one by 25%. A slightly larger error would not matter, but I do not understand by hoe much you are varying the total BF, 0.65 what? Which is the relative error on the total exclusive BF you are assuming? Are you floating B0 and B+ independently? thanks Ric > > "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, 4 Feb 2003, Alessio Sarti wrote: > > > Hi all, > > I've tried to understand what is the error that we want to use in our > > theoretical sys study when varying the exclusive BRs. > > The first point that needs to be clear is that I'm assuming that all the > > various excl B->ulnu BR are related by isospin relations. > > So, once evaluated the error, ALL the exclusive contributions can be > > varied within the error by the same factor. > > The problem now is what error can be quoted. > > I've find out the papers were the measurement are discussed (they're > > linked in http://www.slac.stanford.edu/~asarti/recoil/sys/theor_sys.html > > webpage). Those are two cleo papers. > > The last one is marked 16, Jan 2003. All the various measurements are > > reviewed. It is clearly said that the only two indipendent measurements > > are the B0 -> pi and B0 -> rho one, while all the others are obtained via > > isospin correlations. > > So I've focused my attention on them. > > In the DECAY.DEC we have exactly the same values as those ones quoted in > > PDG: so the error quoted in PDG directly applies to our excl. BR > > measurement. The only attention must be paid weighting the errors coming > > from rho and pi decays. Those two errors are slighlty different (+/- 60 > > (symm) on pi and +0.6 -0.7 (asymm) for rho. > > Should I do the weighted average of those two errors (given that the > > values are exactly scaling with our DECAY.DEC value) and come up with an > > asymm error or should I use a symm err of ~0.65 (reasonable error for > > doing the sys study)? > > > > It might also be said that values quoted in latest CLEO paper are slightly > > different from those ones quoted in PDG but they're all quite consistent > > within the present errors, so I propose to stick to PDG errors/values... > > > > Let me know any doubt/question. > > Cheers, > > Alessio > > > > ______________________________________________________ > > Alessio Sarti Universita' & I.N.F.N. 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") > > >