1. Summary of Recent Results on Rare Decays of B Mesons from BaBar for the BaBar Collaboration Lake Louise Winter Institute Chateau Lake Louise 20-26 February 2011 Bruce A. Schumm Santa Cruz Institute for Particle Physics University of California, Santa Cruz Searching for New Physics via Effective Flavor-Changing Neutral Currents

2. BaBar LLWI 2011: Rare Decays at BaBar2 Bruce Schumm Outline Recent (past year) results are in three areas: B  K l + l - with Missing Energy B  K (limit) B  K  +  - (limit) B    (limit) b  (s,d)  Penguins CP Violation in Penguin Decays (measurement) B  →  X d  and the Status of |V td /V ts | (measurement)

3. BaBar LLWI 2011: Rare Decays at BaBar3 Bruce Schumm The BaBar Dataset 54 fb -1 426 fb -1 BaBar collected 468 M BB pairs between 2000-2007 and 54 fb -1 off-resonance data

4. BaBar LLWI 2011: Rare Decays at BaBar4 Bruce Schumm Flavor-Changing Neutral Currents and New Physics B +  K + The Basic Story: FCNC process in SM require loops  suppressed rates New physics can enter at same order Modification of BF (x10 or greater!) Large CP-violating effects But always a battle against backgrounds… For example: Standard Model Contribution from Extended Higgs Sector

5. BaBar LLWI 2011: Rare Decays at BaBar5 Bruce Schumm B  K,K  Approach Mitigate backgrounds by tagging recoil B meson Tagging B Meson B  K Tag with reconstructed exclusive SL decay;   1% B  K  Tag with fully reconstructed Hadronic decay;   0.2% Signal B Meson K  Selection: Cut-Based K Boosted Decision Tree Missing energy Whole-event properties Signal kinematics Reconstruction quality K Selection: Multivariate Algorithm (Boosted Decision Tree)

6. BaBar LLWI 2011: Rare Decays at BaBar6 Bruce Schumm B  K ,K Results K Result: Phys. Rev D82, 112002 (2010) SM Expectation  4x10 -6 W. Altmannshofer et al., JHEP 04, 022 (2009) G. Buchalla et al., PRD63, 014015 (2000) K  Result (Preliminary): SM Expectation  2x10 -7 J.L. Hewett, Phys. Rev. D53, 4964 (1996) (But New Physics effects coupling to m 2 f could approach measured limit) Momentum Transfer to  +  - System Comparison of results, B +  K + PRELIMINARY SM Expectation

7. BaBar LLWI 2011: Rare Decays at BaBar7 Bruce Schumm B   SM Expectation ( Bosch & Buchalla, JHEP 0208:054, 2002 ) Form B  candidates from photon pairs after likelihood-based  0 rejection B(B  ) = (1.7  1.1(stat.)  0.2(syst.)) x 10 -7 (1.9  significance) B(B  ) < 3.2 x 10 -7 (90% CL) arXiv:1010.2229; to appear in Phys. Rev. D

8. BaBar LLWI 2011: Rare Decays at BaBar8 Bruce Schumm Radiative Penguins I: A CP in b  (s,d)  Tagging B Meson X High Energy Photon Inclusive Radiative Penguin Reconstruction Reconstruct single high-energy photon 2.1 < E *  < 2.8 GeV Reduce backgrounds by requiring lepton on tagging side Charge of lepton tags flavor on signal side Standard model expectation: Any signal would be an unambiguous signature of new physics. PRELIMINARY (Lepton from SL decay)

9. BaBar LLWI 2011: Rare Decays at BaBar9 Bruce Schumm Motivation and Interpretation  (b  s  ) leading indirect constraint on new physics (SUSY, extended Higgs, extra dimension…)  (b  d  )/  (b  s  )  0.03  Precise measurements of  (b  d  ) even more constraining? Practicalities: Rate depends on hadronic effects  Normalize to V ts by measuring corresponding s-quark process Rate depends on poorly constrained CKM parameter V td  Play off against B mixing, which also measures V td sensitively  Compare effective values of |V td /V ts | from B mixing and radiative penguins decays (different diagrams!); discrepancy implies new physics V t(s,d) Radiative Penguins II: b  d  (“X d  ”) and V td /V ts V ts(d ) (d)

10. BaBar LLWI 2011: Rare Decays at BaBar10 Bruce Schumm Radiative Penguins II: b  d  (“X d  ”) and V td /V ts Initial approach: Reconstruct B  ( ,  )  and B  K *  ; |V td /V ts | from  [B  ( ,  )  ]/  [B  K *  ] More current (“X d  ” Analysis) : Reconstruct “semi-inclusively” via sum of seven exclusive decay modes; |V td /V ts | directly from  [b  s  ]/  [b  d  ] Use two independent hadronic system mass ranges 0.6 < M X < 1.0 ( ,  “resonant” region) 1.0 < M X < 2.0 Together, comprise ~2/3 of total width

11. BaBar LLWI 2011: Rare Decays at BaBar11 Bruce Schumm B  X d  Results Result of fit to seven B  X d  modes in high mass region 1.0 < M X < 2.0 GeV/c 2 First observation of b  d  transition above resonance ( ,  ) region No evidence for new physics in b  d  transition Relative accuracy of b  d  constraint approaching that for b  s  transition Has impact of this constraint been fully examined? Phys. Rev. D 82, 051101(R) (2010) Theory Error

12. BaBar LLWI 2011: Rare Decays at BaBar12 Bruce Schumm Summary New limits on B  K and B  K  B(B  K + ) < 1.3 x 10 -5 approaching SM expectation of B(B  K + )  4 x 10 -6 B(B   ) < 3.2 x 10 -7 ; consistent with expected B(B  ) = b  (s,d)  Penguins No observed CP violation in b  (s,d); -0.05 < A CP < 0.16 at 90% CL First observations of b  d  in non-resonant region; |V td /V ts | from b  → d  consistent with that from B mixing; relative accuracy of constraint approaching that of b  s .

13. BaBar LLWI 2011: Rare Decays at BaBar13 Bruce Schumm

14. BaBar LLWI 2011: Rare Decays at BaBar14 Bruce Schumm K * Region 1.0 < M had < 2.02.0 < M had XSXS XdXd MEASURED UNMEASURED  and X d analyses X d analysis only M had (M Xd ) #  0 # bodies #  0 # bodies MEASURED UNMEASURED 0.6 < M had < 1.0

15. BaBar LLWI 2011: Rare Decays at BaBar15 Bruce Schumm Fate of “Snowmass” MSSM study points … on some of our favorite scenarios …

16. BaBar LLWI 2011: Rare Decays at BaBar16 Bruce Schumm C.F. BergerC.F. Berger, J.S. Gainer, J.L. Hewett, T.G. Rizzo,J.S. GainerJ.L. HewettT.G. Rizzo “Supersymmetry Without Prejudice”, arXiv:0812.0980v1 [hep-ph]arXiv:0812.0980v1 Explore 10 7 points over 19- dimensional parameter space of CP-conserving MSSM b  s  most effective constraint (72% of models surviving prior constraints are eliminated; better than direct searches for SUSY partners) … and just in general.

17. BaBar LLWI 2011: Rare Decays at BaBar17 Bruce Schumm