1. Radiative and Electroweak Penguin Decays of B Mesons Jeffrey D. Richman University of California, Santa Barbara B A B AR Collaboration 11 th International Conference on B Physics at Hadron Machines Oxford, Sept. 28, 2006

2. Outline Overview: a little history, physics goals, and challenges B +   +  B 0   0  B 0   and the  extraction of |V td /V ts | B  K l + l - and B  K* l + l - : search for new physics using the lepton forward-backward asymmetry Inclusive B  X s  branching fraction measurements and extraction of heavy-quark-expansion parameters (including m b ) using the E  spectrum Conclusions Apologies for not covering all results on radiative/electroweak penguin decays in this talk!

3. Radiative penguin decays of B mesons Observation of B  K*  CLEO II (1993): Loops in B decays! PRL 71, 674 (1993): cited >500 times! Now it’s a physics program! Rare, but not all that rare!

4. Probe SM at 1-loop level (flavor-changing neutral currents) Search for new physics: can affect amplitudes at leading order As for semileptonic decays, the amplitude in EM/EW penguins involves only one hadronic current  factorizes. What can we learn from b  s, d transitions? (+ W + W - box diagram) (dominated by t quark)

5. Understand QCD dynamics: single hadronic current allows us to isolate non-perturbative parameters in well-defined way. Can be related to same/similar parameters for other decays.  Exclusive decays: decay form factors f i (q 2 ). b  s transition is similar to b  u (heavy-to-light decays)  Inclusive decays: parameters of heavy-quark expansion (m b,   2,…); important input for |V ub |, |V cb | extractions. Measure/constrain CKM elements (|V td /V ts |): if info on hadronic parameters is available from data, theory, or both. What can we learn from b  s,d transitions?

6. Ali, Lunghi, Parkhomenko, PLB 595, 323 (2004) [for I-spin avg.] I-spin (  ), quark model (  ). Expect small I-spin violation: (1.1+/-3.9)%. Ball and Zwicky, JHEP 0604, 046 (2006) Ball and Zwicky, hep-ph/0603232 + W annihilation diagram (small) Observation of b  d  and Measurement of |V td /V ts |

7. Measurement of b  d  Decays (Belle) Signal BK*BK* continuum background Belle, PRL 96, 221601 (2006); 386 M BB. Good particle ID is critical in this measurement to suppress B  K*  feed- down.

8. Measurement of b  d  Decays (B A B AR ) signal bkgnd signal + bkgnd BABAR, hep-ex/0607099, 347 M BB B++B++ B++B++ B 0   0  B00B00 projections of 4-D fit

9. Comparison of b  d  Branching Fractions Mode B A B AR (10 -6 ) (6.3  signif.) Belle (10 -6 ) (5.1  signif.) PRL 96, 221601 (2006). preliminary; hep-ex/0607099 CKM fitter includes CDF B s mixing result. Error on CKM Fitter prediction includes uncert. on B  V  form-factor ratio. I-spin consistency?

10. Extracting |V td /V ts | from b  d  Decays Belle, PRL 96, 221601 (2006). BABAR, hep-ex/0607099 (preliminary) (used CDF hep-ex/0606027) Consistent within errors! courtesy M. Bona (UTfit collab.) Theoretical uncertainties already or soon limiting both approaches. CDF, hep-ex/0609040 (preliminary) exptthy expt thy

11. B  Kl + l - and B  K*l + l - in the SM and Beyond Photon penguin 3-body decays  dependence of rate on kinematic variables can be used to study the different amplitudes and their interference effects. The mode B  Kl + l - is allowed as well as B  K*l + l - (B  K  forbidden by conservation of angular momentum). Z penguin W + W - box

12. B  K*l + l - Dalitz plot Can see A FB behavior and q 2 dependence from the Dalitz plot Note: B  Kl+l- is expected to have very small A FB, even in presence of new physics; effectively provides a crosscheck. effect of  pole Standard Model Prediction

13. Amplitude for B  K*l + l - Short-distance physics encoded in C i ’s (Wilson coefficients); calculated at NNLO in SM: Interference terms generate asymmetries in lepton angular distribution over most of q 2 range. C i ’s can be affected by new physics; enters at same order as SM amp. mix of Z-penguin, W + W - box photon penguin dom. at v. low q 2 Kruger and Matias; PRD 71, 094009 (2005) Ali et al., PRD 61, 074024 (2000)

14. Form Factors and Observables Long distance QCD physics is mainly described in terms of form factors, which are functions of 4 semileptonic form factors: A 1, A 2, V, A 0 (similar to B  D*l, B   l  3 penguin form factors: T 1, T 2, T 3 Form factor uncertainies  35% uncertainty in rate predictions. large s

15. Predictions for A FB in B  K*l + l - : SM and beyond Standard Model s 0 : Ali, Kramer, Zhu, hep-ph/0601034

16. B A B AR, PRD 73, 092001 (2006) 229 M BB B  Kl + l - and B  K*l + l - Signals from B A B AR (6.6 , rarest observed B decay) (5.7  )

17. B  K ( * ) l + l - Signals from Belle Belle, PRL 96, 251801 (2006) 386 M BB (Data sample used for study of Wilson coefficients)

18. B  Kl + l - and B  K*l + l - branching fractionsMode B A B AR (10 -6 ) [208 fb -1 ] Belle (10 -6 ) [253 fb -1 ] preliminary, hep-ex/0410006PRD 73, 092001 (2006) Inclusive: HFAG avg.

19. B  K*l + l - : B A B AR results on K* polarization SM K* polarization Theory predictions in graphs: Ali et al., PRD 66, 034002 (2002); Ball and Zwicky, PRD 71, 014029 (2005). Data apply in 2 bins of q 2 high q 2 low q 2 J/  (vetoed) Polarization consistent with SM, but doesn’t discriminate against new physics scenarios with current data sample. BABAR, PRD 73, 092001 (2006) SM

20. B  K*l + l - : B A B AR results on A FB and  L SM q 2 range (GeV 2 ) A FB FLFL Data excluded at 3.6  ! Any A FB 2.7  use in 2 bins of q 2 (A FB =0 in SM and many BSM)

21. : B  K*l + l - : Belle results on A FB Belle, PRL 96, 251801 (2006) best fit with A 7 fixed to SM for reference:

22. B  K*l + l - : Belle results on Wilson coefficients fix |A 7 | to SM (B  X s  ) fit for A 9 /A 7 and A 10 /A 7 data consistent with SM quadrants I, III excluded at 98.2% C.L. SM fit A 10 >0 (A i are real and constant; q 2 dep. corrections fixed to theory) Fit q 2 and cos  l for need A 9 A 10 <0 to get A FB >0 in upper q 2 region allowed excluded

23. Inclusive B  X s  Canonical process for studying b  s transition. Theory uncertainties currently at 10% level (NLO); pushing toward 5% (NNLO). Huge theoretical effort to predict branching fraction & photon energy spectrum. Also predictions for CP and I-spin violation. Spectrum is insensitive to new physics but is sensitive to m b and Fermi motion of b-quark (“shape function”). T. Hurth, E. Lunghi, W. Porod, Nucl. Phys. B 704, 56 (2005). M. Misiak and M. Steinhauser, hep-ph/0609241 NNLO M. Neubert, Eur. Phys. J. C 40, 165 (2005). all for New!

24. Challenges of measuring inclusive B  X s  Weak experimental signature: single high-energy photon + event- shape cuts. Huge background from  0 ’s and  ’s! Difficult to carry analysis down to E  < 2.0 GeV. Want to push toward 5% precision to match the expected precision of NNLO calculations. MethodAdvantagesDisadvantages Fully inclusive Don’t reconstruct X s Closest correspondence to inclusive B(B  X s  ). Weak kinematic constraints  larger background E  known in Y(4S) frame, not B frame (smearing).  (E   MeV Sum-of-exclusive e.g., BABAR: 38 modes! Less background due to additional kinematic constraints (m ES,  E). Better E  resolution. More model dependence due to finite set of explicitly reconstructed B  X s  decays.

25. Fully inclusive B  X s  CLEO, PRL 87, 215807 (2001), 9.1 fb-1 Measure for E  >2.0; extrap. to E  >0.25 GeV Belle, PRL 93, 061803 (2004), 140 fb -1 Belle, hep-ex/0508005 (moments) Measure for E  >1.8 GeV; extrap. to full background subtracted efficiency corrected background subtracted not efficiency corrected

26. Fully inclusive, lepton-tagged B  X s  (B A B AR ) Suppress large continuum background using Event-shape cuts (continuum has jet topology) Lepton tag: high energy lepton from 2 nd B in event (B  X c l ) qq + ττ BB XSγXSγ continuum dominated BB dominated (blinded) lepton tag hep-ex/0607071 (preliminary, submitted to PRL)

27. B A B AR Fully Inclusive B  X s  w/lepton tag hep-ex/0607071 (preliminary, sub. to PRL) Spectrum from best fit to kinetic scheme. Spectrum from best fit to shape function scheme. (extrapolated, kinetic scheme) (measured) spectrum not efficiency corrected stat sys model

28. B A B AR B  X s  with Sum of Exclusive Final States B A B AR, PRD 72, 052004 (2005) Energy RangeBranching Fraction (10 -4 ) E  >1.9 GeV E  >1.6 GeV (extrapolated) averages over two shape-function schemes errors: stat, sys, variation of shape fcn params E  MomentsValue (GeV or GeV 2 ) E  (min) = 1.897 GeV K*(890) for BF, sum over all m(X s ): continuum signal comb. BB peaking bknd for spectrum, fit m ES in bins of m(X s ) BF/10 -3

29. Summary: B  X s  Branching Fraction & Moments Buchmüller and Flächer, PRD 73, 073008 (2006) HFAG 2006: common corrections to for BFs for extrapolations to E    GeV. Gambino and Uraltsev, Eur. Phys. J C34, 181 (2004) green band expt uncert. average stat+sys b  d  frac shape fcn

30. Fits to moments of inclusive B  X c l and B  X s  distributions all moments kinetic mass scheme Buchmüller and Flächer, PRD 73, 073008 (2006) Data from BaBar, Belle, CDF, CLEO, & DELPHI m b used for |V ub | (7.5% error!)

31. Studies of radiative/electroweak penguins have moved far beyond B  K* . Observation of exclusive b  d  decays: B  (  0,  +,  )  Use to extract |V td /V ts |; consistent with value from B s mixing. Precision soon to be limited by theoretical uncertainties. Electroweak penguins decays B  K l + l -, B  K* l + l -, and B  X s l + l - have been measured. First studies of decay distributions have been performed and exclude some non-SM scenarios. More data needed to exploit full potential. Inclusive B  X s  measurements provide information on m b and non-pert. QCD parameters and help improve precision on |V cb | and |V ub |. Difficult issues with systematic errors, but goal is to achieve 5% uncertainty on branching fraction. We will study radiative/EW penguins for many years to come at BaBar, Belle, and LHC-b! Conclusions

32. B A B AR

33. Backup slides

34. Extracting |V td /V ts | from b  d  Decays Belle, PRL 96, 221601 (2006). BABAR, hep-ex/0607099 (preliminary) CDF, hep-ex/0606027 (preliminary) Consistent within errors. Theoretical uncertainties limiting both approaches. BR(B→(ρ/ω)γ)/BR(B→K*γ) Belle 2005 CDF measurement (  m S ) B-Factories average BaBar ICHEP 2006 CKM fitter code w/o Δm s

35. B 0   BABAR, hep-ex/0607099, 347 M BB

36. B  Kl + l - and B  K*l + l - : q 2 distributions J/   (2S)K q2q2 q2q2 SM nonres SUSY models Pole from K*  even in  +  - constructive interf. destructive

37. B  Kl + l - and B  K*l + l - : the J/  veto The decays B  J/  K and B  J/  K* are huge backgrounds and must be carefully removed (also B   (2S)K,  (2S)K*). These backgrounds are restricted in q 2, but there is a tail due to bremsstrahlung in the electron modes. But B  J/  K and B  J/  K* are valuable control samples; use them to study efficiency of almost any analysis cut. Ali, Kramer, Zhu: B  Ke + e - J/  and  (2S) veto: MC B  Ke + e - e + e - )B  Ke + e - m(e + e - ) projection: MC B  Ke + e -

38. M(l + l - ) distributions from B  J/  K + control samples: data vs. Monte Carlo absolute normalization points: data histogram: MC Bremsstrahlung tails well described by MC. B A B AR

39. B  Kl + l - Signal from B A B AR summed over all K l + l - modes (K + e + e -, K +  +  -, K S e + e -, K S  +  - ) significance=6.6  rarest observed B decay (averaged) B A B AR, PRD 73, 092001 (2006) 229 M BB

40. B  K*l + l - Signal from BAB AR B A B AR, PRD 73, 092001 (2006) 229 M BB

41. B  K*l + l - Dalitz plot Can see A FB behavior and q 2 dependence from the Dalitz plot Note: B  Kl+l- is expected to have very small A FB, even in presence of new physics; effectively provides a crosscheck. effect of  pole Standard Model Prediction

42. B  K*l + l - Dalitz plot Can see A FB behavior and q 2 dependence from the Dalitz plot effect of  pole Maximal new physics effect:

43. B  K*l + l - : B A B AR results on q 2 distribution BABAR, PRD 73, 092001 (2006)

44. Lepton angular distribution in l  l  rest frame use l - if B use l + if B Ali, Kramer, Zhu, hep-ph/0601034

45. Extracting A FB and F L in bins of q 2 B A B AR, PRD 73, 092001 (2006)

46. Belle, hep-ex/041006

47. Inclusive B  X s  some history CLEO, PRL 74, 2885 (1995); 2.01 fb -1 on Y(4S), 0.96 fb -1 below Y(4S) Backgrounds: B decays, continuum, e + e -  qq  (ISR), e + e -  qq   0 X “Event-shape analysis”“B-reconstruction analysis” scaled off resonance total background (points w/error bars)

48. B A B AR B  X s  with Sum of Exclusive Final States Reconstruct 38 exclusive modes |  E|<40 MeV For E  spectrum, fit m ES distrib. in bins of m(X s ) Correct for efficiency of each mode and missing modes fraction (  model dependence) for BF, sum over all m(X s ): continuum signal comb. BB peaking bknd

49. Systematic Errors on B  X s  Belle, PRL 93, 061803 (2004)

50. Belle: B  X s l + l - Belle, PRL 72, 092005 (2006) 5.4 

51. Extraction of heavy-quark expansion parameters from B  X s  B  X s  inclusive E  spectrum B  X c l inclusive E l spectrum and M(X c ) hadron mass distrib. m b now determined to about 1% and |V cb | is determined to <2%. (measures kinetic-energy-squared of b-quark) Using heavy-quark expansion (HQE), moments of inclusive B decay distributions can be expressed in terms of non-perturbative QCD parameters and quark masses.

52. Predictions for A FB in B  K*l + l - : SM and beyond Standard Model s 0 : Ali, Kramer, Zhu, hep-ph/0601034

53. B  K*l + l - : B A B AR results on A FB and  L SM q 2 range (GeV 2 ) A FB FLFL Data excluded at 3.6  ! Any A FB 2.7  use in 2 bins of q 2 (A FB =0 in SM and many BSM)