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Hi all,

 let's look carefully at the fit results with the official cut ch=0 and
the looser cut ch = -1,0,1

 http://www.slac.stanford.edu/~daniele/vub/off.eps    ch = 0

 http://www.slac.stanford.edu/~daniele/vub/ch101.eps  ch = -1,0,1

 If you look at the subtracted plot (right one) you will see that the two
distributions are pretty similar exept for the forth bin.

 In

 http://www.slac.stanford.edu/~daniele/vub/compch0-ch101.eps

 I overlay the two distributions. The problem in the forth bin is clear
from this plot. The agreement for the remaining plots is nice and the
increase is compatible with the increase you expect in the signal efficiency
(~25%).

 I ran also the Mx scan with the cut ch = -1,0,1

 scan

 http://www.slac.stanford.edu/~daniele/vub/newmxstudy.ps

 difference with uncorr error (default is 1.55GeV)

 http://www.slac.stanford.edu/~daniele/vub/compmxstudy.ps


 The behaviour seems to be pretty unstable. At 1.2 the difference with the
default is 2 sigmas. I would like to point out that with a harder cut on
Mx the results with ch = -1,0,1 and ch = 0 are very compatible.

 We could conclude that the different value we get with ch = -1,0,1 is a
consequence of a wrong background estimation close to the D mass and not
of a wrong signal efficiency. Since the result is very unstable as a
function of Mx this wrong bkg estimation is in the ch = -1,1 sample.

 Daniele