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Hi guys, here is a lot of inside information from Belle on their way to re-weight the D**lnu MC kindly provided by Elisabetta and Phill after a discussion I had with Elisabetta at Beauty06. Clearly, there is a bunch of things to digest. Once we have fixed the SP5/SP6 bug there is certaintly additional room for improvements. Cheers, Heiko ---------- Forwarded message ---------- Date: Fri, 20 Oct 2006 06:55:25 +1000 (EST) From: Phillip Urquijo <[log in to unmask]> To: Heiko Lacker <[log in to unmask]> Cc: "[log in to unmask]" <[log in to unmask]> Subject: Re: D** re-weighting Hello Heiko, For the D** component of the MC we make use of 1/mQ corrections to the Isgur-Wise functions used to describe the differential decay rate of B->D** l nu, given in: A.K.Leibovich, Z.Ligeti, I.W.Stewart, M.B.Wise, Phys. Rev. D57, 308(1998). These models allow us to both; correct the w (the dot product of the four velocity of the B meson, and that of the recoiling D( ) meson) distributions of those produced using the Isgur-Wise functions in the MC, and to provide bounds on the less well known broad resonant branching fractions. We use experimental constraints from the ratios: R_(semileptonic) = BR(B->D1 l nu) / BR(B->D*2 l nu), (mostly from hep-ex/0112028 ) R_(hadronic) = BR(B->D1 pi) / BR(B->D*2 pi) (using factorisation) (K. Abe etal. BelleCollaboration, PRL94, 221805(2005): this paper also provides mass measurements of the D** components) as well as BR(B -> D1 l nu) and limits on BR(B->D*2 l nu) (PDG). There are 3 variables describing the corrections, which are additionally bound by theoretical arguments. The differential decay rates are calculated for the components: D*0, D*1 (wide), and D1, D*2 (narrow). There are five models discussed in the theory paper, split into two groups, A group (decay rates expanded in (w-1)), and B group (decay rates expanded in w). The difference between the expansions is suggested to provide an estimate of the theoretical uncertainty associated to the 1/mQ corrections. We can determine bounds on the semileptonic ratios: BR(B->D*1 l nu) / BR(B->D1 l nu), BR(B->D*0 l nu) / BR(B->D1 l nu), BR(B->D*2 l nu) / BR(B->D1 l nu), Using these ratios in combination with BR(B -> D1 l nu), we determine the BR for the remaining D** components. We check for consistency with BR(B->D(*)pi l nu) (D. Liventsev, T. Matsumoto et al, (The Belle Collaboration), published in PRD 72, 051109(R) (2005)) and full semileptonic rate measurements (HFAG), based on assumptions/measurements of D** ->D pi pi decay rates (see K. Abe etal. BelleCollaboration, PRL94, 221805(2005)). On a technical note, we used privately developed code by DELPHI (not written by the author) written in fortran, to perform the differential decay rate calculations. Interestingly there are quite significant changes to the q^2 distributions. ( w = ( mB^2 + mD(*)^2 - q^2 )/( 2 mB mD(*) ). Let me know if you would like more information/references. Best Regards, Phillip Urquijo On 19/10/2006, at 2:28 AM, Heiko Lacker wrote: Hi, some time ago I send you this email and maybe it was lost. Quantitative information on this re-weighting would be very welcome. Cheers, Heiko On Mon, 2 Oct 2006, Heiko Lacker wrote: Hi Phill, I had a chat with Elisabetta at Beauty06 about your D** re-weighting procedure after I have seen how well the MC describes the mX spectrum measured in Belle's moment's analysis of B-Xclnu. She told me that I can contact you to get quantitative details about how the D** part of the MC has been re-weighted. I would appreciate any further insight in what has been done. Cheers, Heiko