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Hi Antonio,

can we also have a look at the plots for the MX fits, 
both for signal-enriched and signal-depleted?

I'm curious, after all re-weightings discussed so far,
how the fit performs above 2 GeV.

Cheers,
Heiko

On Tue, 26 Sep 2006, Antonio Petrella wrote:

> Hi,
> on the web page where I posted results of systematics due to 
> randomization of S/P:
> 
> http://www.slac.stanford.edu/~petrella/systsp.html
> 
> you can see that this systematic error is not stable, for example when 
> cutting on integrated purtity.
> 
> Now I'm trying to look at other results from these jobs to see if I can 
> find what makes this errors so large, but probably this is also due to 
> the S/P ratio and its error.
> 
> For example if you look at the correction factors for IP > 0.50
> (http://www.slac.stanford.edu/~petrella/tmp/SP_allrew/SPallweights/ip050_allrew/corrallwip050pol1.eps)
> 
> you can see that the first bin has a large error (the exact value of the 
> correction factor for this bin is S/P = 5.67 +- 5.34)
> 
> These numbers (they're on the spreadsheet at
> http://www.slac.stanford.edu/~petrella/tmp/SP_allrew/SPallweights/SoverPFullRew.sxc)
> come from the double ratio of S/P on MC (0.74 +- 0.13) times the S/P 
> ratio on data depleted sample
> 
> (http://www.slac.stanford.edu/~petrella/tmp/SP_allrew/SPallweights/ip050_allrew/data_depl_AC_intp0.50_0.001.55.eps)
> 
> On data depleted sample the signal component (fitted) is 291 +- 31 and 
> the background component (fitted) is 38 +- 35, so the error on the final 
> S/P ratio is driven by the background component on data depleted 
> sample... and cutting on purity (and having less background) will give 
> roughly higher errors on background component (at least the statistical 
> error).
> 
> For the data depleted sample we get S +- dS and P +- dP as they come out 
> from the fit and then we compute the quantity S/P +- d(S/P). But these 
> errors are correlated, aren't they?
> 
> ciao,
>    Antonio
>