Hi,

> I agree we cannot correct SP5 to look like SP6. However, by determining
> separate correction factors we definitely get a better data-MC agreement
> and get confidence that the fit is working OK. Here are the errors on
> the correction factors:
>
> Entire sample (Run1-4, SP5+6):
>
> Chi Square of the Fit = 4.48376
> NDOF = 7
> ratio other/vcb  =  0.60 +- 0.07
> Vcb comp = 0.188267 +- 0.00631457
> Oth comp = 0.113042 +- 0.0125698
>
>
> This is what Kerstin got on separate samples:
>
> > > > **Fit on Run 1+2, SP5:
> > > > chi2/ndof = 1.64116 (for 7 dof)
> > > > ratio other/vcb = 0.296045 / 0.287339 = 1.03 +- 0.17
> > > > (with errors:
> > > > Vcb comp = 0.287339 +- 0.0183957
> > > > Oth comp = 0.296045 +- 0.0442523)
> > > >
> > > > **Fit on Run 4, SP6:
> > > > chi2/ndof = 1.90748 (for 7 dof)
> > > > ratio other/vcb = 0.117799 / 0.141224 = 0.83 +- 0.13
> > > > (with errors:
> > > > Vcb comp = 0.141224 +- 0.00785652
> > > > Oth comp = 0.117799 +- 0.0174853)
>
>
> A couple of warnings
>
> 1) I previously run the fits WITHOUT the B&D reweighting (-b -d flags),
> so I run them again and the ratio on the entire sample went from 0.55 to
> 0.60. I hope Kerstin was more clever than me and run with -b and -d ;-)
I did run with -d -b.

> 2) Wolfgang mentions that the signal has been reweigthed to match the
> Run1+2/Run3+4 luminosity ratios ub data. A point related to this is:
> what happens if you run on Run1+2 or Run4 only?
As long as the magic k numbers are correct, applying the weights to SP5
when running on Run1+2 should not hurt I think, as it only changes the
effective number of events (as most of the other reweightings do), but it
keeps the relative fraction as we want them.

> In this case you should
> not apply any reweighting at all and you should also use different magic
> factors. Did anybody check this?
I did recompute the magic k numbers when we introduced this SP5/SP6
correction. I am sure I did it for the full statistics and I just
crosschecked with my notes that I also recomputed the numbers for the
individual run periods as they are in wfermifile.dat, assuming the SP5 vs.
SP6 reweighting will be done independent of the run flag. So I think
things are used consistently here.

Cheers,
Kerstin


> A similar reweighting should be done for vcb+other background, I guess.
>
> Ciao, Concezio.
>
>
> Il giorno gio, 20-07-2006 alle 07:40 +0000, Wolfgang Menges ha scritto:
> > Hi Kerstin,
> >
> > Kerstin Tackmann wrote:
> > > Hi Concezio,
> > >
> > >> if we stay with SP5/6 I think that reweighting the D** wrt D+D*
> > >> separately for SP5 and SP6 would be the best we can do. But this means
> > >> that we need to know whether we are analysing SP5 or SP6 events when we
> > >> build the datasets in VVF, which I am not sure how to do.
> > >> Using SP8 means a lot of extra work/checks/tunings.
> > >> However it is not clear to me why when we compute the D** reweighting we
> > >> get 1 for SP5 and 0.83 for SP6, whereas we get 0.55 for (sp5+sp6). Well,
> > >> the fit might be just readjusting itself...
> > > Would we actually want to trust it if it is readjusting by so much?
> >
> >
> > Well, checking with data would be better but we have to rely on MC here.
> >   One thing nobody meantioned is the error on this ratios or the ratio
> > of the D** components to the total background.
> >
> > And you can see clearly from the numbers that something else is going
> > on. Otherwise you will not end up with (1+0.83)/0.55. Or is this to naive?
> >
> > Cheers,
> >
> > 	Wolfgang
> >
>
>