Hi, 
here are some results for the double ratio 

(signal/peakingBG)_MCenriched
-----------------------------
(signal/peakingBG)_MCdepleted


as a function of mx. We use this double ratio, multiplied by the ratio
(signal/peakingBG) in the depleted data sample, in order to fix the
(signal/peakingBG) components in the mES fits on data after all cuts as
a function of mx. 

The various signal (S) and peakingBG (P) components of this double ratio
on MC can be computed on either:

(1) the entire MC sample, by performing a 3-parameter fit to S, P and
combinatorialBG (B) 

or 

(2) on separate "signal" (reconstructed Breco mode == true Breco mode)
and "background" (reconstructed Breco mode != true Breco mode) samples.
In this case, the signal sample is used to determine S, whereas the
background sample is used to determine P and B. 

Method (2) has a number of advantages on method (1): 
- the uncertainty on S and P is smaller 
- the bias on S is reduced, since we don't risk to mix up/swap signal
and peaking background due to the very similar functional forms of their
PDFs. 

The spreadsheet attached to this message proves the above two
statements. 

The upper part of the spreadsheet contains the results obtained with
method (1), the lower part refers to method (2).  Look e.g. at the
errors on the peaking background numbers on the enriched sample on
column E5-E14 for method (1) and E18-E27 for method (2). The same is
true on the depleted sample (column Q) and for the signal yields
(columns K and W). 

The bias in method (1) on the number of fitted signal and background
events (columns I5-I14, U5-U14 for signal, AH5-AH14, AI5-AI14 for
background) is also evident by comparing them to the number of expected
events in the datasets (respectively: columns AI18-AI27, AI31-AI40 for
signal, AH18-AH27, AH31-AH40 for background). 

The double ratios which come out are flat as a function of mx and are
compatible with 1, see the light blue cells in the spreadsheet, or the
attached eps file (The number for the last bin in mx is not meaningful
since there are very few events in the mES plot). 

The bottom line is that the signal/peaking background in the mES fitss
can be fixed in our data to the values which we obtain on the depleted
sample, times a MC correction which turns to be about 1 within 10% and a
~10% uncertainty, which gets higher at high mx. 

This is not the end of the story, of course. The study needs to be
repeated on the MC samples which we use in VVF (vcb+other, vubIN,
voubOUT), since we have to fix the signal/peaking background components
in there as well... 

Stay tuned, Antonio&Concezio.