Ciao Alessio,
thanks for the incredibly patient work you are doing ...
There is something fishy in your results, but I hope we can converge
easily now that you have done the bulk of the effort.

A few preliminary remarks to try and understand what is going on:

1) the plots right above the first table of your page and the example you
quote reports a situation which is not believable (if I understand
correctly): huge changes in D(*)lnu which I can;t believe (you claim a
factor 2 in Dlnu). And actually if I understand that the second table is
the DlnuX BF table (can you please write it out explicitely?) the Dlnu
almost does not change and the D*lnu is off by "only" 20%.

2) how much is the total B->(*,**)Dlnu systematics?

3) in the D branching fraction section, can you please show the Mx
distributions also in the >1.6GeV  region?

4) in the D BR systematics, did you adjust for the measured BF or for the
DECAY.dec one? The measured BF might always have a selection bias. Also
can you try doing the systematics varying only one well known BF (D0->KPi
for istance) and checking the systematics actually comes negligible/?

	thanks
	ric

On Fri, 17 May 2002, Alessio Sarti wrote:

> Hi all,
> the D systematics study has reach a crucial point.
> You can see in the updated web page
> (http://www.slac.stanford.edu/~asarti/recoil/sys )
> that the various D BR are extracted and the systematic is computed in a
> 'new' way:
> the BR are fixed to random values extracted accocrdingly to a gaussian
> distribution centered at PDG with PDG values for the sigma.
>
> The systematic effect is REALLY large. This is a very conservative way to
> extract the systematics. Sometimes we rely on the DECAY.DEC effect: the
> generated BR is far from the PDG one.
> Some other times is the PDG that has very large errors (this affect the
> systematics only in a 'statistical' way..)
> The other problems are coming of course from a BAD event reconstruction
> and those are the most dangerous from our point of view.
> the web page describes a little some of the main effects and
> contributions, but the work to understand such large syst. is ongoing...
>
> Any comment and help is really appreciated.
>
> Alessio
>
> ______________________________________________________
> Alessio Sarti
>  Universita' & I.N.F.N. Ferrara
>  tel  +39-0532-781928  Ferrara
> roma  +39-06-49914338
> SLAC +001-650-926-2972
>
> "Vorrei tanto sapere chi e' che va in giro a costruire quadrati
> sull'ipotenusa"
>
>