Interpreting CP asymmetries in
B CP asymmetries Tree diagram: Penguin diagram: need |P/T| and =arg(P/T) R t /R c R u /R c
Theoretical frameworks 1.strong isospin symmetry SU(2) (GL) CP-averaged Br(B ) only ( 0 0 not seen yet) EW penguins neglected SU(3) flavour symmetry (BF,Ch) OZI-suppressed annihilation penguins neglected No correction of SU(3) breaking |P | from K 0 - (GR,BBNS) R th from QCD factorisation Neglect annihilation diagram in K 0 - remains unconstrained 4.QCD factorisation (BBNS) Use the prediction of both |P/T| and Non-factorisable 1/m b contributions fixed to default value use Br(B 0 K + - ) and |P | = |P K | GL: Gronau, London, Phys.Rev.LettD65:3381,1990 BF: Buras,Fleisher, Phys.Lett.B360:138,1995 Ch: Charles, Phys.Rev.D59:054007,1999 GR: Gronau, Rosner, Phys.Rev.D65:013004,2002 BBNS: Beneke et al., Nucl.Phys.B606: ,2001
Experimental inputs ICHEP’02 Branching fractions (x10 -6 ) WA = BaBar + Belle + CLEO Global CKM fit using standard constraints (referred as standard CKM fit in this talk) BaBarBelle S 0.34– 1.23 0.42 C – 0.30 0.25– 0.77 0.28 sign convention changed! not seen CKMFitter: Hoecker et al., Eur.Phys.J.C21,225,2001 and ICHEP02 Aspen03 32 CL range:
BABAR Belle Constraints in the ( ) plane from isospin analysis BABAR Belle Gronau,London,Sinha,Sinha bound: Grossman-Quinn 98; Charles 99; Gronau-London-Sinha-Sinha 01 no significant constraints
Constraints in the ( ) plane: SU(3) BABAR Belle Charles 99 no significant constraints
Constraints in the ( ) plane: |P + – | from K 0 - BABAR Belle
BABAR Belle Constraints in the ( ) plane:QCD Factorisation Negative C and small positive negative BABAR Belle
What about ? BABAR Belle At present, significant theoretical input needed to extract
QCD Factorisation: uncertainty from hard spectator interaction and annihilation diagram BABAR Belle no zoom Non-factorisable power-suppressed contribution parameters free
Constraints/predictions on |P/T| and (C , S ) and ( , ) from standard CKM fit non-factorisable contributions free theoretical parameters varied within a given range uncertainty from ( , ) non-factorisable contributions fixed
Predicting C and S using , from standard CKM fit Only predictive approach: QCD Factorisation. poor knowledge of sin2 large uncertainty in S
Constraint on Br(B 0 0 ) Inputs = C , Br(B + - ), Br(B + 0 ) Moriond’02 Belle measurements ! ! Gronau-London-Sinha-Sinha 01 S C
How about More Statistics? Isospin analysis for present central values, but 500 fb –1 (BaBar C ,,S and WA branching fractions) and even more... The only hope for BaBar and Belle is not to observe B 0 0 0
Various strategies to interpret time-dependent asymmetry measurements C , S studied: –Significant constraints on from QCD Factorisation but still need validation from data –Qualitative information when constraining the penguin amplitude using Br(B - K 0 - ) – Mild assumption frameworks based on SU(2) and SU(3) do not lead to significant constraints If central value of BR( 0 0 ) stays large, isospin analysis probably cannot be performed by first generation B factories Conclusion