Vub measurement using recoil of fully reconstructed Bs


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Antonio Petrella <[log in to unmask]>
05 Jul 2006 17:16:56 +0200Wed, 05 Jul 2006 17:16:56 +0200
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Hi all,

today I've run again two fit tests, one with the ratio signal/peaking 
bkg fixed (only on data, this time) and one without fixing the ratio.

Results can be found here:

General comments:

-comparing the right lower plot (which contains the sum of Bch and B0 
for data)

we see that the effect of fixing the ratio is to increase the 
distribution in the low mx region ( 1.55 < mx < 2.1) and to decrease in 
the high mx region (mx > 2.8 ).

So we looked with more attention to fits performed bin by bin to compute 
the correction factor and...:

- the fit in the high mx region for MC depleted has peaking background 
consistent with 0

moreover in the Enriched MC the signal and the peaking components are 
swapped for 3.1 < mx < 3.4!

- in the low mx region the increase in the mx distribution is due to the 
behaviour of the double ratio (sig/peak)_DATA/(sig/peak)_MC, where the 
numerator and denominator go in the opposite direction i.e.: for MC the 
ratio is small while for data is high, so the net effect of the double 
ratio is to give a high correction.

But fits on MC present clearly some problems: look at

So I don't think we can trust 100% the numbers used to compute the 
correction so far.