Hi Concezio,
indeed, S and P are anti-correlated which increases the errors.
What puzzles me a bit is the fact that the chi^2 is too good. In
other words: At large mX the S/P value should fluctuate more than
it is observed.
If we believe in a constant the systematics on the individual mX bin
for the double ratio would (e.g. for IP>0.2) be 0.1491/1.328: 11%.
This should result in an interesting systematic error on DeltaBRBR
when only taking S/P from MC-enriched and by randomizing S/P by 11%
per bin. Of course, one should add still to this error also the error
on S/P from MC-enriched.
Cheers,
Heiko
On Thu, 5 Oct 2006, Concezio Bozzi wrote:
> Heiko Lacker wrote:
> > * Concezio will produce (S/P)-double-ratios for depleted sample
> > (data/MC) taking into account S/P-correlations in the error
> > calculations in the data-depleted mES fit
> >
> plots which include the correlations are here:
>
> http://www.slac.stanford.edu/~bozzi/SoverP/SoverP_mcdata_depl_020.eps
> http://www.slac.stanford.edu/~bozzi/SoverP/SoverP_mcdata_depl_030.eps
> http://www.slac.stanford.edu/~bozzi/SoverP/SoverP_mcdata_depl_040.eps
> http://www.slac.stanford.edu/~bozzi/SoverP/SoverP_mcdata_depl_050.eps
>
> the spreadsheet used to produce the plots is
> http://www.slac.stanford.edu/~bozzi/SoverP/SoverPFullRew.sxc
>
> Please note that the correlations are not yet taken into account for
> intpur>0.5, as I could not find the appropriate logfile. The effect of
> the correlations is in any case small. Since the S and P are
> ANTIcorrelated (as expected), the error on S/P increase.
>
> Here are the double S/P ratios (MC/data) for different intpur cuts, as
> resulting from a simple p0 fit. Chisquares are also shown.
>
> intpur cut S/P chisquare/nDOF
> 0.20 1.33 +/- 0.15 3.5/9
> 0.30 1.41 +/- 0.16 2.9/9
> 0.40 1.19 +/- 0.17 8.7/9
> 0.50 1.25 +/- 0.17 8.4/9 (no correlations yet)
>
> I would say that data and MC depleted samples agree better and their
> ratio is weakly dependent on mX at higher integrated purity cuts.
> Ciao, Concezio.
>
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