Hi,

On Wed, 5 Jul 2006, Antonio Petrella wrote:

> 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:
> 
> http://www.slac.stanford.edu/~petrella/tmp/scra/Ibutest_fixed/ 
> http://www.slac.stanford.edu/~petrella/tmp/scra/Ibutest_SUN/
> 
> General comments:
> 
> -comparing the right lower plot (which contains the sum of Bch and B0 
> for data)
> 
> http://www.slac.stanford.edu/~petrella/tmp/scra/Ibutest_fixed/test_fixeddatachop_all-1.eps
> http://www.slac.stanford.edu/~petrella/tmp/scra/Ibutest_SUN/test_SUNdatachop_all-1.eps
> 
> 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
> http://www.slac.stanford.edu/~petrella/tmp/AWG38/depleted/MCsameEND/MCfit_1D_3.103.40.eps 
> 
> http://www.slac.stanford.edu/~petrella/tmp/AWG38/depleted/MCsameEND/MCfit_1D_3.403.70.eps
> 
> moreover in the Enriched MC the signal and the peaking components are 
> swapped for 3.1 < mx < 3.4!
This bin is indeed special in the sense that the fit error on the ratio 
sig/peakBG is much smaller than the ones in the neighbourhood and that 
the ratio has a minimum there. I would think that an average over a larger
mX range would be more appropriate. The question is how to define these
larger ranges.

> http://www.slac.stanford.edu/~petrella/tmp/AWG38/enriched/MC/MC_enrich_1D_3.103.40.eps
> 
> 
> - 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
> 
> http://www.slac.stanford.edu/~petrella/tmp/AWG38/depleted/MCsameEND/MCfit_1D_1.551.90.eps
> http://www.slac.stanford.edu/~petrella/tmp/AWG38/depleted/MCsameEND/MCfit_1D_1.902.20.eps
Do these fits correspond to to the two bins where we have the larger 
correction from the double-ratio?
 
Heiko

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