1 ICHEP’04, Beijing, Aug 16-22, 2004 A. Höcker – sin2  in Loop-Dominated Decays with B A B AR The Measurement of sin2β (eff) in Loop-Dominated B Decays with B A B AR Andreas Höcker Laboratoire de l’Accélérateur Linéaire, Orsay ICHEP 2004 August , 2004, Beijing, China For the B A B AR Collaboration Preliminary analyses documented in upcoming B A B AR -CONF-04/33, 04/25, 04/40, 04/19,

2 ICHEP’04, Beijing, Aug 16-22, 2004 A. Höcker – sin2  in Loop-Dominated Decays with B A B AR The Quest for New Physics in B Decays Since the successful and precise measurement of sin2β in decays (in perfect agreement with the SM), considerable effort at B Factories towards the search for specific signs of New Physics (NP)…. WHY ? The gauge hierarchy Problem (Higgs sector, scale ~ 1 TeV) Baryogenesis (CKM CPV too small) The strong CP Problem (why is  ~ 0 ?) Grand Unification of the gauge couplings... many more Note that: if NP contributes significantly to CPV in loop decays, we naturally expect it to be different among the modes  averaging only useful in case of SM see, e.g., the instructive talk by Y. Grossman at LP’03: hep-ph/ Conflict between limits from flavor physics  1 TeV (e.g., K 0, D 0, B 0 mixing), and NP scale (1 TeV)  NP cannot have a generic flavor structure Requires flavor suppression and/or generic suppression and/or alignment

3 ICHEP’04, Beijing, Aug 16-22, 2004 A. Höcker – sin2  in Loop-Dominated Decays with B A B AR Confronting Loop Decays with Tree Dominance High virtual mass scales involved: believed to be sensitive to New Physics decays are tree and penguin diagrams, with equal dominant weak phases decays are pure “internal” and “flavor-singlet” penguin diagrams Both decays dominated by single weak phase Penguin: Tree: New Physics? 33 ?

4 ICHEP’04, Beijing, Aug 16-22, 2004 A. Höcker – sin2  in Loop-Dominated Decays with B A B AR Bronze Silver Gold Penguin Olympia One may identify golden, silver and bronze-plated s-penguin modes: Color-suppressed tree Naive (dimensional) uncertainties on sin2  Note that within QCD Factorization these uncertainties are much smaller ! Color-suppressed tree

5 ICHEP’04, Beijing, Aug 16-22, 2004 A. Höcker – sin2  in Loop-Dominated Decays with B A B AR All Results are PRELIMINARY PRELIMINARY ! Definition of Time-dependent CP asymmetry observables: ~ 0 ~ –  CP  sin(2  ) for b  ccs, sss and with: CP observables

6 ICHEP’04, Beijing, Aug 16-22, 2004 A. Höcker – sin2  in Loop-Dominated Decays with B A B AR Highlights on Common Analysis Techniques Strong DIRC Particle ID to separate pions from kaons Event shape monomials (L 0,L 2 ), and B kinematics optimally combined in Multivariate Analyzer [MVA] (Neural Network (NN) or Fisher Discriminant) New NN-based B-flavor tagging with “Q” up to 30.6 % Unbinned maximum-likelihood fit using beam-energy-substituted B mass (m ES ), B-energy difference (  E), the resonance mass and decay angle, the MVA, and  t Likelihood components are signal (correctly and misreconstructed), continuum background, charmed and charmless B-related backgrounds; as many likelihood-model parameters as possible are determined simultaneously from the fit to reduce systematic errors Tagging-performance parameters and  t resolution parameters determined simultaneously from fit to fully reconstructed B decays to charm B A B AR - DIRC

7 ICHEP’04, Beijing, Aug 16-22, 2004 A. Höcker – sin2  in Loop-Dominated Decays with B A B AR Analysis of B 0   K 0 ML fit finds 114 ± 12 signal events 227  10 6 B pairs 98 ± 18 signal events full background continuum bkg combined fit : Systematic errors dominated by opposite-CP background PDF modeling Tag-side CP violation sin2  0.9 

8 ICHEP’04, Beijing, Aug 16-22, 2004 A. Höcker – sin2  in Loop-Dominated Decays with B A B AR Analysis of B 0/+   K 0/+ B 0  K S B 0  K L (statistical errors only) Complementary penguin mode: Fit finds 400 ± 23 signal events Significant direct CP violation would be hint for New Physics 227  10 6 B pairs

9 ICHEP’04, Beijing, Aug 16-22, 2004 A. Höcker – sin2  in Loop-Dominated Decays with B A B AR Analysis of B 0  K + K – K S (I) 227  10 6 B pairs Excluding  : dominant contribution (85%) of inclusive BR  much more statistics than  K S Unknown a priori CP content: CP-even fraction must be determined experimentally Angular moments analysis (main result): (statistical error only) and: Study  [K + K – ] helicity angle distribution Average moments computed from sum of background-corrected signal weights, returned by ML fit (“sPlot” technique [Pivk-Le Diberder, physics/ ]) Isospin analysis (cross check) [ Belle, PRD 69, (2004)]

10 ICHEP’04, Beijing, Aug 16-22, 2004 A. Höcker – sin2  in Loop-Dominated Decays with B A B AR Analysis of B 0  K + K – K S (II) Fit finds 452 ± 28 signal events (excluding  K S events) Results from CP fit ML fit: Systematic errors dominated by Fit bias Tag-side CP Violation CP content sin2  0.7  use C=0:

11 ICHEP’04, Beijing, Aug 16-22, 2004 A. Höcker – sin2  in Loop-Dominated Decays with B A B AR No CPV found in control sample Analysis of B 0   ’ K S Large statistics mode:, we exploit: Reconstruct in multiple final states:  ’   +  –,  0  and    ,  +  –  0 and K S  +  –,  0  0 Fit finds 819 ± 38 events ML fit : Systematic errors dominated by: Fit bias (MC statistics) 227  10 6 B pairs sin2  3.0  3.0 

12 ICHEP’04, Beijing, Aug 16-22, 2004 A. Höcker – sin2  in Loop-Dominated Decays with B A B AR Analysis of B 0  f 0 K S New, silver-plated s-penguin mode with 209  10 6 B pairs [BABAR, hep-ex/ ] Requires thorough estimate of CP dilution due to interference in B 0   +  – K S Dalitz plot ML fit : Systematic errors dominated by Fit bias & interference with other modes 2.3  Fit finds 152 ± 19 events sin2  0.6 

13 ICHEP’04, Beijing, Aug 16-22, 2004 A. Höcker – sin2  in Loop-Dominated Decays with B A B AR Analysis of B 0   0 K S (I) Challenging vertexing (  t ) due to lifetime of K S :  require at least 4 SVT hits (~60% of events) for  t measurement  determine  t from global fit to entire decay tree (use E beam, IP (+2  B )-constraint)  keep remaining “no-  t ”events for direct CPV measurement 227  10 6 B pairs Replace  E and m ES by: and  reduced correlation, improved resolution (m miss ) mass-constrained Fit finds 300 ± 23 events

14 ICHEP’04, Beijing, Aug 16-22, 2004 A. Höcker – sin2  in Loop-Dominated Decays with B A B AR Analysis of B 0   0 K S (II) sPlot ML fit : Systematic errors dominated by Background tagging asymmetry SVT alignment, vertexing No bias in control sample decays without using J /  -decay tracks for vertexing ~ SM physical limit 11 22 33 sin2  1.3 

15 ICHEP’04, Beijing, Aug 16-22, 2004 A. Höcker – sin2  in Loop-Dominated Decays with B A B AR sin2  (and related direct-CP ) Results from B A B AR s-penguin average at 2.7  from sin2  [cc] (B A B AR only) no indication for direct CP violation

16 ICHEP’04, Beijing, Aug 16-22, 2004 A. Höcker – sin2  in Loop-Dominated Decays with B A B AR Conclusion B A B AR has new sin2  (eff) results for all s-penguin analyses, most using 227  10 6 B pairs The significant decrease in the statistical errors begins to provide precision measurements of CP violation in loop processes The “Stamodometer” indicates for the different modes: s-penguins Introduced and observed new silver-plated s-penguin mode Sophisticated vertexing allows time-dependent measurement of CPV in... and overall: