Hi,

I try to summarize what we have learnt so far if I got
everything correctly (please correct me in case I
missed something):

            mxHad <-> mxHadfit
-------------------------------------------------------
BRBR        Not a big improvement when using mxHadfit
            concerning statistical errors
            However, I would guess that this is not
            any more the case when also considering
            systematics from b->clnu.

Moments     Errors on Moments seem to be significantly
            larger when using mxHad instead of mxHadfit

At least concerning the second topic we would like to use
a kinematic fitter. How well we are really doing using the
VertexTreeFitter is also not known at this stage.

My personal point-of-view:
In this situation the only reasonable thing to do wrt the
CKM workshop is to produce updated numbers for Run1+Run2
concerning:
1) using the new Neubert calculation
2) mX-q^2 result using updated numbers from Zoltan and Co.

In addition one might try to add:
3) One bin-unfolding for mX
4) Further Tests on the unfolding and calculation of moments.

Please give me feedback!

Cheers,
Heiko

On Mon, 17 Jan 2005, Kerstin Tackmann wrote:

>
> Hi Daniele,
>
> > > I ran the VirVubFitter jobs on generic MC using the same genMC files for
> > > the generic MC and as data (as we said on Friday). This uses the ichep
> > > ntuples. You can find the VirVubFitter output in the following directory
> > > at SLAC: ~kerstin/scra.
> > > Taking the numbers from the results.dat for the fitted numbers of events
> > > in the first bin (0..1.55GeV) I find
> > > S/N(mxhadfit) = 1.04
> > > S/N(mxhad)    = 0.98
> > > so the difference is a lot smaller than what Roberto saw on data if I
> > > remember correctly. Maybe someone could check my numbers to make
> > > sure I did not mess it up?
> >
> > your results show that, as far as the BR measurement is concerned, the fit
> > is not useful at all?
> > this is true for the mx analysis with a cut at 1.55 GeV. I am not sure it
> > is the same for a looser cut. If I compare the two ...fitresults.eps
> > files I notice that the "D0/Dc" bin (the second bin in mx) is quite
> > different between mxhad and mxhadfit. This should imply that there is more
> > background for mxhad if you use loose cuts in mx.
>
> Ok, I understand. Would it be the plan to try to go to a higher mX cut or
> would this mean that what we see here might not be the same for mX-q2?
>
> > > Also I computed the moments for the unfolded spectra. Please find the
> > > tables in here:
> > > http://www.slac.stanford.edu:~/public_html/vubfit/moments_data.pdf
> > > The systematics evaluated are the same we had on Friday:
> > > statistical (on spectrum and detector matrix), multiplicity category
> > > reweighting, B->Xclnu BFs, exclusive D BFs, mb and a from Belle, B->Xulnu
> > > BFs (as done for ichep).
> > >
> > > The first four pages have tables for the uncorrected and the bias
> > > corrected moments as obtained on data for mxhad and mxhadfit. Comparing
> > > the uncertainties it looks like we see quite larger uncertainties on some
> > > of the moments using mxhad. This is coming mostly from the systematics
> > > (see the tables where the uncertainties are split up). I tried to figure
> > > out where this comes from. First having a little closer look at the error
> > > bars on the left plot on page 4 of VR011105.pdf from last Friday you can
> > > see that we have larger error bars for mxhad than for mhadfit, so this is
> > > consistent.
> >
> > but do we understand why the error on the subtraction is different?
>
> I think I am not sure what you mean by error on the subtraction. One the
> charm background subtraction? But I think you said on Friday that we would
> expect to have higher uncertainties on the charm subtraction?
>
> Kerstin
>
>