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Tasks

• Provide world averages for measurements related to the angles of the Unitarity Triangle. In particular, we provide world averages of measurements of time-dependent CP violation, and related parameters. We also prepare averages of time-independent measurements that have a clean relation to the UT angles (especially in the B→DK system).
  
  • α ≡ φ₂
    • from time-dependent CP asymmetries in b → uu-bar d decays, like B_d → π⁺π⁻, (ρπ)⁰, ρ⁺ρ⁻, a₁⁺⁻π⁻⁺, …
    • extraction of α ≡ φ₂ via isospin analysis, or interpretation of Dalitz plot parameters
  • β ≡ φ₁
    • from time-dependent CP asymmetries in
      • b → cc-bar s decays, like B_d → J/ψ K_S, J/ψ K*, D*⁺D*⁻ K_S, …
      • colour-suppressed b → cu-bar d decays, like B_d → D π⁰
      • b → cc-bar d decays, like B_d → J/ψ π⁰, D⁽*⁾⁺D⁽*⁾⁻, …
      • hadronic b → s penguin decays, like B_d → φ K_S, η′ K_S, K_S K_S K_S, K⁺K⁻ K_S, …
      • hadronic b → d penguin decays, like B_d → K_S K_S, … (*)
      • radiative b → s γ penguin decays, like B_d→ K_S π⁰ γ, … (*)
    • extraction of sin(2β) ≡ sin(2φ₁) from the B_d → J/ψ K⁰ system
    • resolution of the ambiguity in 2β ≡ 2φ₁
  • γ ≡ φ₃
    • from time-dependent CP asymmetries in b → cu-bar d/uc-bar d decays, like B_d → D*⁺⁻π⁻⁺, …
    • extraction of constraints on |sin(2β+γ)| ≡ |sin(2φ₁+φ₃)| from the above
    • from rates and asymmetries in b → cu-bar s/uc-bar s decays, like B^±→ D⁽*⁾K⁽*^)±, …
    • extraction of constraints on γ ≡ φ₃ from the above
  • φ_s
    • from time-dependent CP asymmetries in b → cc-bar s decays of the B_s meson, like B_s → J/ψφ, …
  (*) These measurements are listed under the β ≡ φ₁ category as much for convenience as for physical reasons.
  
• Identify common experimental and theoretical uncertainties and treat them coherently in the averages. Rescale the measurements if updated input parameters are available.
• In cases where effective UT angles are measured no attempts are made to derive the fundamental quantities, if this requires input from QCD calculations.
• If straightforward, an interpretation of the results is given.

Averages

Averages are updated around the times of major conferences; speakers at such events are encouraged to contact the HFAG CP(t)/UT group members listed below in order to obtain the latest results which may not yet be posted officially. Requests for updates between major conferences are also welcome, though satisfaction cannot be guaranteed.

Documentation

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Contact for the Sub-Group

You can send a mail to the entire group with the major-domo list hfag-tri@slac.stanford.edu