Difference: AsymmetryFitting (5 vs. 6)

Revision 62010-08-20 - AlisonBates

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META TOPICPARENT name="WebHome"

B2hh GFact Asymmetry Fitting page

The aims for the asymmetry fitter are the following

  • Perform basic checks of current fitting package with toy data for Bd and Bs asymmetries (see below).
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  • Implement an automatic method such that when the mass region is changed, the normalisation for the pdfs is changed.
 
  • Add proper time pdf to the fitting package (started looking at this below).
  • Add Bs→KK pdf to fit package
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  • Think about adding the other background pdfs (3 body, Λ's)
 
  • Alter the parameters that are being varied by the minimiser to d, θ and γ
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  • Move to MC data/ real data (Bd) for first looks. So far 0.3fb-1 data is enough for asymmetry fitter

Most of the following is on my web page http://ppewww.physics.gla.ac.uk/~alison/B2hh.html where all the attached files are there and work. I have now stopped using my web page and will now just post all my results here.

>
>
  • Think about adding the other background pdfs (3 body, Λ's)
  • Move to MC data/ real data (Bd) for first looks. So far it looks like around 0.3fb-1 data is enough for asymmetry fitter
 

Basic Checks with asymmetry fitter

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>		 Toy data was generated with a mix of 56.1% Bd → π π, 10.3% Bd → K π and 33.6% combinatoric background with ssb of 0.664 (ssb is S/S+B) generated in a mass region of 5-5.8 GeV. The mistag rates in generation and fitting was ωBs = 0.361and ωBd = 0.355 and ACPBd→Kπ = 0.1.

Adir Bd - input was 0.38 and fitted was 0. ± 0. ( AdirBd)
Amix Bd - input was 0.61 and fitted was 0. ± 0. ( AmixBd)

Everything below is out of date and will be removed as soon as the above is updated with the newest and unbiased results. Jobs running now.

 

1. Bd → π π

50 datasets were generated with 6099 events per data set using 0.68 b2pipi (sf1=1 and ssb = 0.68) and 0.32 combinatoric background (MassDistribution) mass distribution. The asymmetry fitter was used to fit for Bd asymmetries only with sf1'=0.68 and obtained the following:
Adir Bd - input was 0.38 and fitted was 0.3953 ± 0.0476 ( AdirBd)
Amix Bd - input was 0.61 and fitted was 0.6503 ± 0.0311 ( AmixBd)
Then re-ran same job with 150 data sets with 2000 events per data set and fitted for the following:
Adir Bd - input was 0.38 and fitted was 0.4338 ± 0.0196 ( AdirBd)
Amix Bd - input was 0.61 and fitted was 0.6619 ± 0.0197 ( AmixBd)
The asymmetry plot is shown here .

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