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Thank you Kerstin for posting all these nice plots.

My observation is the following:
  -  the dominant B to XC l nu background is not well described,
     thus your background subtracted distributions look poor
     in many cases.
  -  Of course the distributions that are the most difficult to 
     reproduce are multiplicities, both charged and neutrals,
     in the recoil only, and also the total charge in the event 
     (which includes the Breco charge).
     What are the cuts on the momentum/energy of charged
     and neutral particles in the recoil? 
     The total charge distribution for the enriched sample
     of neutral B gets very asymmetric in data.  Is this a loss
     of negative slow pions in data due to interactions?
     the effect is much smaller in the charged B, for which
     you do not apply the D* l nu veto.
   - have you tried to change the purity of the Breco selection,
     to see whether this might cause problems? or enlarge the q2 cut
     on the recoil?
   - Do you understand the large change in charged multiplicity between 
     enriched and depleted samples?  The neutral multiplicity increases
     for the enriched samples, the charged multiplicity decreases.
     Does this point to problems with the enriched MC?  Jet-set 
     fragmentation?
   - the enriched Emiss-Pmiss and MM*2 distributions do not 
     show the expected peaks. Emiss-Pmiss= MM2/(Emiss+Pmiss) assumes 
     a linear dependence of the MM2 resolution on Emiss.
     Have you checked MM2 vs Emiss? 
     I do not understand the motivation of the additional
     cut on the MM^2.  
   - Have you tried to look at these distribution with fewer bins
     on Mx?

So many questions, no clear answers?

Ciao
Vera



-----Original Message-----
From: [log in to unmask] [mailto:[log in to unmask]] On Behalf Of Kerstin Tackmann
Sent: Friday, August 31, 2007 2:26 PM
To: vub-recoil
Subject: Data-MC Agreement (again)


Dear vub-recoilers,

as you probably know, we are seeing some problems in the data-MC 
agreement. The most recent plots are here:
http://costard.lbl.gov/~kerstin/vubunf/ana32/dataMC/dataMC_KLcorr.html

We obtain these plots as follows:
*Remove the cut on the given variable from the analysis.
*Perform the fit to the mX spectrum with this selection.
*Rebin the data and MC in the variable under study and use
  the *comp from the previous fit to mX to scale the MC
  components.

The main concern is about the neutrino variables and Qtot.

If we could have plots using this technique for the Vub analysis, that
would be a very interesting comparison, from which we could hopefully
learn and which would help us a lot in the review. I would really
appreciate if someone could look into this (as soon as possible)
-- please let me know if that would be possible. I'd be happy to give
more technical details, just let me know if something isn't quite clear!

Thanks so much,
Kerstin