1. Michael Milnik (University of Karlsruhe) for the CDF Collaboration Search for Rare b-Hadron Decays at CDF II HEP 2007, Manchester

2. 2007/07/21HEP 2007, Manchester 2 Covered in This Talk  B s/d →   B →  h  B u →  K  B d →  K *  B s →   Results from CDF on B 0,B s →h + h - ’ covered by M. Morello later in this session

3. 2007/07/21HEP 2007, Manchester 3 Motivation:  In the SM, B→  heavily suppressed (need FCNC) expectation:  B d →  further Cabbibo-suppressed  Expect to see nothing, if something seen  new physics Search for B s/d →  A.J. Buras, Phys. Lett. B566, 115 (2003)

4. 2007/07/21HEP 2007, Manchester 4 Search Methodology 1.Unbiased (blinded) selection optimisation using signal event sample: MC simulation background sample: data sidebands 2.Normalize to well-known B → J/  K decay  cancellation of many systematic effects 3.Apply cuts on search mode and normalization mode 4.Estimate Backgrounds 5.Unblind

5. 2007/07/21HEP 2007, Manchester 5 Selection Procedure Form likelihood ratio from following discriminating variables:  displacement of reconstructed B vertex (long B lifetime)  isolation (expect B to be isolated)  “pointing angle” between reconstructed B momentum and direction to primary vertex (should be small)  Optimize on best limit with 90% C.L. P  PP PP L 3D x y B s    R < 1 (  < 57 o )     z 

6. 2007/07/21HEP 2007, Manchester 6 Apply Selection  Observation in agreement with background expectation  Set limits

7. 2007/07/21HEP 2007, Manchester 7 Results World’s best limit

8. 2007/07/21HEP 2007, Manchester 8 Search for B→  h  Non-resonant decays B →  h via box or penguin diagrams  new physics may be observable through interference with SM amplitudes  Already observed (BaBar, Belle):  B u →  K  B d →  K*  Missing:  B s →    prediction: BR(B s   )=1.6x10 -6 PRD 73, 092001 (2006) PRL 96, 251801 (2006) C.Q. Geng and C.C. Liu, J. Phys. G 29, 1103 (2003)

9. 2007/07/21HEP 2007, Manchester 9 Search Methodology  Similar method than for B s →   Unbiased (blinded) selection optimisation using  signal event sample: MC simulation  background sample: data sidebands  Normalize to analogous resonant B → J/  h decay  Apply cuts on search mode and normalization mode  Remove resonant  by cutting out J/  /  (2S) mass ranges  Unblind

10. 2007/07/21HEP 2007, Manchester 10 Optimize selection based on cuts on similar quantities as used for B s →  (decay length, isolation, pointing angle) Optimize on best value for Selection Strategy

11. 2007/07/21HEP 2007, Manchester 11 Observations B u →  KB d →  K * B s →  # events signal range903511 # estim. BG events45.3 ± 5.816.5 ± 3.63.5 ± 1.5 Significance 4.5  2.9  2.4 

12. 2007/07/21HEP 2007, Manchester 12 Results BR(B + →  K + ) = [0.72 ± 0.15(stat.) ± 0.05(syst.)]x10 -6 BR(B 0 →  K*) = [0.82 ± 0.31(stat.) ± 0.10(syst.)]x10 -6

13. 2007/07/21HEP 2007, Manchester 13 Summary & Outlook  CDF set limits for B s/d →   currently probe the 10 -8 level  limits severely constrain new physics models  growing dataset will allow deeper probing in the future  CDF investigating B →  h modes  results in agreement with those of b-factories  most stringent limit on B s →   More data – better results: watch out!

14. 2007/07/21HEP 2007, Manchester 14 Backup

15. 2007/07/21HEP 2007, Manchester 15 B s/d →  Backgrounds Estimate backgrounds from: sidebands (combinatoric) branching fractions B→h + h - and fake rates