Hi Wolfgang, Neubert supports the fit to the spectrum for both the old
calculation (which is commonly referred as 'Kagan&Neubert') and the
current BLNP calculation. It is not true that the fit to the moments is
more accurate, it is just different and interesting as well. For the
future Vub paper, quoting from an exchange of emails we had with Matthias,
he says: "However, I still think that
for the Vub extraction it may be better to follow the route using the
generator, since the B->Xu l nu spectra are predicted with the same theory
at NLO."
Where for 'generator' he refers to the notebook we got, and for
b2sgamma then this means to use the differential BF.
I am happy to discuss further this topic... the fit to the spectrum is
correct and supported by the authors and the parameters obtained should be
used for the extraction of Vub.
		Francesca


On Thu, 28 Jul 2005, Wolfgang Menges wrote:

> On Fri, 29 Jul 2005, Concezio Bozzi wrote:
>
> > 1) We have been asked by the referee of our paper hep-ph/0504071 to
> > comment on the sentence:
> >
> > "However, there are concerns that the extraction of the shape function
> > parameters from the photon spectrum in B->Xs gamma is less reliable"
> > (p.18 before section 7)
> >
> > Could you explain to what you are referring to?
> >
>
> Actually, Vera and I have added this and, as written, it should hint to
> the fact that the extraction of the shape function parameters from the
> moments are more reliable than from the shape. To be more explicitly, this
> should be seen in the context that we are using the shape function
> parameters extracted from the Belle b->sgamma spectrum [hep-ex/0407052]
> which uses the Kagan-Neubert prescription. To my understanding
> Kagan-Neubert is not as sophisticated as BLNP but I am not sure what the
> authors have said about the reliability of their calculations.
>
> We would have prefered shape function parameters extracted from moments of
> the b->sgamma spectrum but this wasn't finished in time for LP05. For the
> paper this will be different.
>
> Cheers,
>
> 	Wolfgang
>
>
>
>