1. Bayesian analysis at work troublesome examples
J. Charles, A. Hoecker, H. Lacker and F. Le Diberder

2. Outline Setting the stage Frequentist analysis Bayesian analysis
Simplified stage
Concerns and Conclusion

3. Setting the Stage α B decays into π π final states 6 observables And
6 theoretical
unknown
6 decay amplitudes
are involved CP
Violation α

4. α

5. Bayesian Analysis α Data Theoretical parameters: mind
are random variables
- following known PDF
mind

6. Quantum Mechanics parameterization
6 decay amplitudes
are involved
One phase may be set to zero
Bayesian (I)
frequentist

7. Standard model parameterization
The 6 amplitudes
are split into two
kind of contributions
Trees & Penguins
10^9
Bayesian (II)
amplitudes & phases
… or
real & Imaginary parts ?
Bayesian (II)
frequentist
Bayesian (III)

8. Changing decay channel (ρρ)
Bayesian (I)
Bayesian (II)
!?!
Quantum Mechanics
amplitudes & phases
JHEP 0507:028,2005
frequentist
(I)(II)(II)
real & imaginary parts
Bayesian (III)

9. B → π π
Taking key experimental information away
removing all
experimental hints
related to α
amplitudes & phases
Quantum Mechanics

10. Conclusion
… that attractive ?
priors
parameterization

11. Spheres within a cube Simplified Stage 6 D space
Bayesian treatment
one knows nothing about
the individual space
components x,y,z…
What do we known
about the radius
r =√(x^2+y^2+…) ?

12. Concerns & Conclusion α
CKM
Should we ?