Presentation on theme: "Heavy Flavor Averaging Group David Kirkby UC Irvine"— Presentation transcript:
Heavy Flavor Averaging Group David Kirkby UC Irvine http://www.slac.stanford.edu/xorg/hfag/ http://belle.kek.jp/mirror/hfag/
D. Kirkby, UCI 2 Brief History HFAG is successor to LEP/SLD/CDF heavy- flavor working-groups. Established at May 2002 FPCP conf. as natural transfer of primary responsibility to Babar & Belle. Lesson from history [ t (B s ) from 1994 Moriond/LaThuile]: reliable averages require careful attention to methodology.
D. Kirkby, UCI 3 HFAG Mission Primary mission: provide averages of “heavy flavor” (B d,B s ) quantities for major conferences (summer/winter) and PDG. Secondary: standard reporting of analysis details standard reporting of analysis details develop & maintain averaging tools develop & maintain averaging tools build community consensus on methodology build community consensus on methodology develop new ways to summarize complex averages develop new ways to summarize complex averages
D. Kirkby, UCI 4 Organization b-hadron lifetimes B oscillations DG s V cb V ub B time-dependent Semileptonic decays Unitarity triangle Rare decays KEK, SLAC (flavor)CERN (flavour)
D. Kirkby, UCI 5 Methodology I Types of uncertainty & correlations handled: stat. syst1. syst2. syst3. syst4. … stat. syst1. syst2. syst3. syst4. … measurement A measurement B
D. Kirkby, UCI 6 Methodology II Assume that systematics correlated between measurements are due to unknown value of some external globally defined parameter. E.g., B lifetime used to determine B oscillation frequency.
D. Kirkby, UCI 7 Methodology III Approximate (n+1)- dim. likelihood with n-dim. likelihood, assuming external constraint on global param. more precise than internal constraint.
D. Kirkby, UCI 8 Issues Cannot handle statistical correlations (e.g., due to sample overlaps). Cannot combine multidim. results (e.g., simultaneous t-D m) How to combine measurements of same quantity made with different theoretical assumptions? (e.g., DG ).
D. Kirkby, UCI 9 Looking Ahead Convened task force to make recommendations on Dalitz analysis. Created new WG on b->c decays. Writeup of HFAG methodology & results on track for winter conferences. Involved in CKM2005 workshop.