Difference: AsymmetryFitting (8 vs. 9)

Revision 92010-09-14 - AlisonBates

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META TOPICPARENT name="WebHome"

B2hh GFact Asymmetry Fitting page

The aims for the asymmetry fitter are the following

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  • Perform basic checks of current fitting package with toy data for Bd and Bs asymmetries (see below).
  • 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
  • Alter the parameters that are being varied by the minimiser to d, θ and γ
  • Think about adding the other background pdfs (3 body, Λ's)
  • Move to MC data/ real data (Bd) for first looks.
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  1. Perform basic checks of current fitting package with toy data for Bd and Bs asymmetries. In process of checking by Alison and will copy below once completed..
  2. Implement an automatic method such that when the mass region is changed, the normalisation for the pdfs is changed. DONE by Paul.
  3. Add proper time pdf to the fitting package. Stand alone model of pdfs done - see below.
  4. Alter the parameters that are being varied by the minimiser to d, θ and γ.
  5. Think about adding the other background pdfs (3 body, Λ's).
  6. Move to MC data/ real data (Bd) for first looks.

PDF modeling for Bs

The basic pdf of

f(t,tmin, signal)=N*exp(-t/τ)[1+q(1-2ω)(Adir.cos(Δmt)-Amix.cos(Δmt))]

with standard values has been plotted with q=+1 (red) and q=-1 (blue) and gives the following distribution. The integrated area from tmin to 10.0 is 0.994402.

BsKKPDFnoPTres.gif

I am studiying the pdf obtained from the following distribution

f(t|tmin,signal)=N.1/τ.exp(-t/τ)[1+q(1-2ω){Adir.cos(Δmt)-Amix.cos(Δmt)}Θ(t)conv 1/√2πexp-(t'-t)^2/2σ^2

and obtained the following for q=+1 (red) and q=-1(blue).

BsKKnewPDF.gif

 

Basic Checks with asymmetry fitter

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. 100 data sets with 100,000 events per data set was used here but Lars ran with 1000 data sets with 100k events per set and found no bias on the pulls and much improved uncertainties. I just show the plots below (100 data sets) for completion.

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META FILEATTACHMENT attachment="B2pipiB2KpiCBAdirnew.gif" attr="" comment="" date="1282552940" name="B2pipiB2KpiCBAdirnew.gif" path="B2pipiB2KpiCBAdirnew.gif" size="15497" stream="B2pipiB2KpiCBAdirnew.gif" tmpFilename="/usr/tmp/CGItemp26948" user="AlisonBates" version="1"
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META FILEATTACHMENT attachment="BsKKPDFnoPTres.gif" attr="" comment="" date="1284477759" name="BsKKPDFnoPTres.gif" path="BsKKPDFnoPTres.gif" size="7857" stream="BsKKPDFnoPTres.gif" tmpFilename="/usr/tmp/CGItemp25414" user="AlisonBates" version="1"
META FILEATTACHMENT attachment="BsKKnewPDF.gif" attr="" comment="" date="1284477773" name="BsKKnewPDF.gif" path="BsKKnewPDF.gif" size="7801" stream="BsKKnewPDF.gif" tmpFilename="/usr/tmp/CGItemp25423" user="AlisonBates" version="1"
 
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