1. 18 th November 2005 Guillaume Thérin 1 Lausanne –  measurements with Guillaume Thérin LPNHE – Paris Lausanne BaBar Measurements of  detector at SLAC with

2. 18 th November 2005 Guillaume Thérin 2 Lausanne –  measurements with Theoretical context –CP violation –Standard model PEPII and BaBar B-Factory Direct measurements of  –B -  D ( * ) K ( * )- method (ADS, GLW, GGSZ) Direct measurements of sin(2  ) –B 0  D ( * )-  +, D ( * )-  +, B 0  D ( * )0 K ( * )0 Combinations of the results with CKMFitter Outline

3. 18 th November 2005 Guillaume Thérin 3 Lausanne –  measurements with Theoretical context

4. 18 th November 2005 Guillaume Thérin 4 Lausanne –  measurements with The CKM matrix elements V ij describe the electroweak coupling strength of the W to quarks The CKM mechanism introduces quark flavour mixing CP violation in the Standard Model The phase changes sign under CP. Transition amplitude violates CP if V ub ≠ V ub *, i.e. if V ub has a non-zero phase = CP Complex phases in V ij are the origin of SM CP violation

5. 18 th November 2005 Guillaume Thérin 5 Lausanne –  measurements with Structure of the CKM matrix –Mixing is weak  Magnitude of elements strongly ranked (leading to ~diagonal form) 3 particle generations and unitary CKM matrix: 4 parameters (3 real + 1 im.)  = arg( V* ub / V cb ) (Wolf.) Unitarity Triangle /3/3 /2/2 /1/1 V td V tb * V ud V ub * V cd V cb * (  ) V cd V cb * Wolfenstein : Measuring SM CP violation  Measure complex phase of CKM elements 3 real par. A, λ (= sin  Cabibbo = 0.22) and ρ 1 imaginary par. iη (responsable of CP violation) (  )(  )

6. 18 th November 2005 Guillaume Thérin 6 Lausanne –  measurements with http://ckmfitter.in2p3.fr CP violation studies established: Experimental Constraints on the Unitarity Triangle Before the B-factories, constraints came from kaons, B oscillations and |Vub/Vcb| B-factories can be used to over-constrain the triangle and so to test the SM sin(2  ) = 0.685 ± 0.032 experimental contraints on   (this talk) harder to measure The SM test consists of comparing 2 kinds of measurements :  P (new physics) B decays in charmless 2-bodies (envolving amplitudes with penguins) charmonium b  cus,b  ucs b  cud,b  ucd b  cus,b  ucs  st (Standard Model), B -  D ( * ) K ( * )- (GLW, ADS, GGSZ) B 0  D ( * ) , D 0 K ( * )0 (  or sin(2  )) B s  D s K ( * )0 (probably at LHC)

7. 18 th November 2005 Guillaume Thérin 7 Lausanne –  measurements with PEPII / BaBar, Experimental apparatus

8. 18 th November 2005 Guillaume Thérin 8 Lausanne –  measurements with 3.1 GeV 9 GeV The PEP-II B factory - Specifications BB threshold  (4S) Produces B 0 B 0 and B + B - pairs via Y(4s) resonance (10.58 GeV) Asymmetric beam energies Low energy beam 3.1 GeV High energy beam 9.0 GeV Clean environment ~28% of all hadronic interactions are BB

9. 18 th November 2005 Guillaume Thérin 9 Lausanne –  measurements with RUN1 RUN2 RUN5 RUN3 Most analyses are based on 232.10 6 BB pairs RUN4 Trickle injection: w/o trickle injection top-off every 30-40 min continuous filling with trickle injection more stable machine, +35% more lumi The PEP-II B factory - Performance PEP-II top lumi: 1.x10 34 cm -2 s -1 (~10 BB pairs per second) Integrated luminosity PEP-II delivered: 311 fb -1 BaBar recorded: 299 fb -1 on- peak+off-peak data Most analyses use 211fb -1 of on- peak data Records:

10. 18 th November 2005 Guillaume Thérin 10 Lausanne –  measurements with B A B AR Collaboration : 11 countries and ~590 physicists ! Solenoid : 1.5T ElectroMagnetic Calorimeter : 6580 CsI crystals (Tl)  E)/E = (2.32 E –1/4  1.85)% Support tube Instrumented Flux Return : iron / RPCs [ → LSTs ] The BaBar detector Drift CHamber : 40 layers  (p T )/p T = (0.13 p T  0.45)% Detector of Internally Reflected Cherenkov light : 144 quartz bars, 11000 PMs K/  > 2.5  (p < 4.3 GeV/c) Silicon Vertex Tracker : 5 layers of double-sided Silicium, vertex resolution of 60-120  m

11. 18 th November 2005 Guillaume Thérin 11 Lausanne –  measurements with Selecting B events for CP analysis B mesons identification m ES EE e + (3.1 GeV) e - (9 GeV) b udsc Signal isotropic E* beam very well known e + e - → uu, dd, ss, cc e + e - → bb -2 –1 0 1 2 3 4 Fisher discrimnant E* beam = E* Υ(4S) / 2 K/  separation with Cherenkov angle Excellent separation between 1.5 and 4 GeV/c Combinatorial e + e -  qq bkg suppression Jet-like E* beam 2 m B > ~

12. 18 th November 2005 Guillaume Thérin 12 Lausanne –  measurements with Constraining  with B -  D ( * ) K ( * )- decays Gronau-London-Wyler method Atwood-Dunietz-Soni method Giri-Grossman-Soffer-Zupan method Combination Introduction

13. 18 th November 2005 Guillaume Thérin 13 Lausanne –  measurements with B-B- b u c u s u D0D0 K *- V cb V us Constraining  with B ± → D ( * ) K ( * )± decays a a r B e i(  ) B-B- b u s u u c D0D0 K *- V ub  = arg( V* ub / V cb ) Favored decay b  c Strong phase CKM Angle Suppressed decay b  u Ratio of the 2 amplitudes r B ≈ 0.1-0.2 D 0, D 0  same f  interference sensitive to  : ff –Gronau-London-Wyler : CP eigenstates –Atwood-Dunietz-Soni : DCSD D 0 and CA D 0 ex. : B - → (K +  - ) D K - Ks0Ks0 KsKs K+K-K+K- ++ KsKs –Giri-Grossman-Soffer-Zupan : D 0 → K s     K+-K+- Ks-Ks- r D / r B ≈ 0.5 B(B -  D ( * ) K ( * )- )  5. 10 -4 ! r B, , different for DK* ±, DK ± and D*K ± modes

14. 18 th November 2005 Guillaume Thérin 14 Lausanne –  measurements with Constraining  with B -  D ( * ) K ( * )- decays Introduction Atwood-Dunietz-Soni method Giri-Grossman-Soffer-Zupan method Combination Gronau-London-Wyler method

15. 18 th November 2005 Guillaume Thérin 15 Lausanne –  measurements with GLW - Observables of the method - B ±  D ( * ) K ±( * )    A(B+→D CP K *- ) A(B- →D CP K *+ ) A ( B  →D 0 K*  ) Observables are: non-CP modes ≈ flavour eigenstates N(B + → D K* + ) ≠ N(B - → D K* - ) Direct CP violation:

16. 18 th November 2005 Guillaume Thérin 16 Lausanne –  measurements with A + R + = - A - R - Extract the 3 unknowns ( , r B,  ( * ) B ) for each mode from 4 observables  a relation between observables: 8-fold ambiguity in  Sensitivity on  depends on r B D ( * ) K modes suffer from bkg from D ( * )0  (12x higher BF)  need excellent  /K separation D ( * ) K* modes cleaner but lower BF and lower efficiency need to consider D ( * ) K s  irreductible component Need to take into account dilution effect from opposite-sign CP D 0 decays in fK S 0 and  K S 0 (for instance D 0  a 0 K S 0 ) D*K* need angular analysis -not realistic with current statistics GLW - Characteristics of the method - B ±  D ( * ) K ±( * ) Experience: Theory:

17. 18 th November 2005 Guillaume Thérin 17 Lausanne –  measurements with Event Shape Variables cos(  of B momentum m ES &  E mass (D 0 ) D 0 helicity D0D0 BB mass (K S 0 ) distance of flight mass (K*) K* helicity K*  Ks0Ks0 232 millions of charged B decays Reconstructed BF of the order of 2.10 -7 – 10 -6 CP=+1 : K  K ,    , non-CP : K   , K     0 , K  3  D0D0 track PIDs CP+, non-CP mass (K S 0 ) distance of flight CP- : K s 0 X. X = {    } Ks0Ks0 mass (  )  helicity dalitz angle track PIDs  mass (  0 ) 00 mass (  )  helicity track PIDs  GLW – Reconstruction and selection - B ±  D K ± * -- -- ++

18. 18 th November 2005 Guillaume Thérin 18 Lausanne –  measurements with CP+ : 24 CP- : 25 B+B-B+B- B0B0B0B0 cc uds Signal Adding CP+ modes together (resp. CP- and non- CP) Strategy : fit in one dimension in m es Use data in  E and D 0 mass sidebands to fix the background shape Hypothesis : common parameterisation for all modes (checked on MC) D 0 mass EE m es Gaussian G (r B = 0) Argus function A m es GLW – Distribution of the simulation and fit strategy - B ±  D K ± *

19. 18 th November 2005 Guillaume Thérin 19 Lausanne –  measurements with GLW - Results of the fit for 232 millions of charged B - B ±  D K ± * m(D 0 ) sidebands  E sidebands B+ non-CPCP+1 CP-1 SIGNAL REGION B- One single Gaussian G One single Argus A Simultaneous fit in m es for 3 regions : –Signal –m D0 sidebands –  E sidebands PRD72,71103(2005)

20. 18 th November 2005 Guillaume Thérin 20 Lausanne –  measurements with B  D 0 K: 232M B ± decays, D 0  KK,  K S 0  0 A 2  cut on  C in these plots B  D* 0 K: 123 B ± decays, only D* 0  D 0  0, D 0  KK,  at the moment: Main background from kinematically similar B→D 0  which has BF 12x larger –So the signal and this main background are fitted together Kaon hypothesis GLW - Results - B ±  D ( * ) K ± Only CP+ modes 3D Fit(m es,  E,  C ) without the kaon hypothesis 2D fit to  E and the Cherenkov angle of the prompt track

21. 18 th November 2005 Guillaume Thérin 21 Lausanne –  measurements with GLW – Summary - B ±  D ( * ) K ±( * ) No asymmetry seen All values compatible with 1 except for the DK* mode  r B is bigger than expected for this mode 1 0

22. 18 th November 2005 Guillaume Thérin 22 Lausanne –  measurements with Constraining  with B -  D ( * ) K ( * )- decays Introduction Gronau-London-Wyler method Giri-Grossman-Soffer-Zupan method Combination Atwood-Dunietz-Soni method

23. 18 th November 2005 Guillaume Thérin 23 Lausanne –  measurements with ADS - Method - B ±  D ( * ) K ±( * ) B-B- b u c u s u D0D0 K *- B-B- b u u c D0D0 Cabibbo favoured b  c amplitude Cabibbo suppressed b  u amplitude s u s u u d u d u s r B = Cabibbo suppressed c  d amplitude Cabibbo favoured s  u amplitude r D = r D = 0.060±0.003 Sensitivity: r D / r B ≈ 0.5 Better sensitivity than GLW but lower BF 4-fold ambiguity in  : need to measure at least two D decay modes to loose ambiguity between  and the strong phase

24. 18 th November 2005 Guillaume Thérin 24 Lausanne –  measurements with m ES (GeV/c²) ~90 events ~4 events RS WS WS B + WS B - Cut same variables as GLW Some of them are put in a neural network ADS – Results of the fit - B ±  [K  ± ] D K ±( * ) ± B ±  [K ±  ] D K* ± ± B ±  [K  ± ] D K* ± ± B -  [K +  - ] D K* - B +  [K -  + ] D K* - PRD72,71104(2005)

25. 18 th November 2005 Guillaume Thérin 25 Lausanne –  measurements with 1-CL GLW ADS combination    rBrB  [0,  ] & (  D +  )  [0,2  ]  (deg) 1-CL    (semi-log scale)   [75°,105°] (excluded @2  CL) GLW + ADS – Interpretation - B ±  D K ± * EPJ,C41,1 (2005) CkmFitter Frequentist approach to determine  and r B Construction of Confidence Level plots PRD72,71104(2005)

26. 18 th November 2005 Guillaume Thérin 26 Lausanne –  measurements with hep-ex/0504047 B - →D*[D  0 ]K - B - →D*[D  ]K - B - →DK -  D*→D  0 /D  ≠ in  D* by  (r* B )²< (0.16)² * (Bayesian r* B ²>0 & uniform,   and  D *) PRD70,091503(2004) 0<  D <2  r D ±1  51°<  <66°  r B <0.23* * * * * ADS – Results - B ±  [K  ± ] D(*) K ± ±

27. 18 th November 2005 Guillaume Thérin 27 Lausanne –  measurements with ADS – Summary - B ±  D ( * ) K ±( * ) No signal peak was observed More sensitive than GLW but need more statistics to constrain  Other non-CP modes to add and reduce ambiguities 0

28. 18 th November 2005 Guillaume Thérin 28 Lausanne –  measurements with Constraining  with B -  D ( * ) K ( * )- decays Introduction Gronau-London-Wyler method Atwood-Dunietz-Soni method Combination Giri-Grossman-Soffer-Zupan method

29. 18 th November 2005 Guillaume Thérin 29 Lausanne –  measurements with  Schematic view of the interference Reconstruct B  D (*)0 K (*) with Cabibbo-allowed D 0 /D 0  K S     If D 0 /D 0 Dalitz f(m + 2,m - 2 ) is known (included charm phase shift  D ): B:B+:B:B+: |M  | 2 =  ambiguity only 2-fold (  ↔  ) Experimentally: BF [(B   D 0 K  )(D 0  K 0  )]=(2.2  0.4)10 -5  High statistic Only charged tracks in final state  high efficiency/low bkg GGSZ – Dalitz Method - B ±  D ( * ) K ±( * )

30. 18 th November 2005 Guillaume Thérin 30 Lausanne –  measurements with f(m 2 +,m 2 - ) extracted from high statistics tagged D 0 events (from D *  ) D decay model described by coherent sum of Breit-Wigner amplitudes  D  phase difference determined by model Not so good for  s-wave. Need controversial  and  ’(1000) to reasonably describe the data Masses and widths fixed to PDG2004 values except for  and  ’ (fitted) 13 fitted resonances + NR term +  +  ’  2 /dof  3824/3022=1.27 DCS K*(892) CA K*(892)  (770) GGSZ – D 0  K S     Dalitz model f - B ±  D ( * ) K ±( * )

31. 18 th November 2005 Guillaume Thérin 31 Lausanne –  measurements with Mode Signal events B -  DK − 282 ± 20 90 ± 11 B -  D*[D  ]K − 44 ± 8 B -  DK* − [K 0 S  - ] 42 ± 8 B -  D*[D  0 ] K − DK - D*[D  0 ]K - D*[D  ]K - hep-ex/0504039 (m ES >5.27 GeV/c²) B -  DK* − [K 0 S  - ] GGSZ – Fit results - B ±  D ( * ) K ±( * )

32. 18 th November 2005 Guillaume Thérin 32 Lausanne –  measurements with  (deg) k. rs B 0<k<1 is an extra parameter with no assumption made on (K 0 S  - ) under the K*- part 2  CL 1  CL GLW+ADS 11 11 22 GGSZ/GLW+ADS – Confidence regions - B ±  D K ± *  (deg) GGSZ rBrB More constraint with GLW/ADS for this mode than with GGSZ (K 0 S  - ) under the K* - and K  S-waves accounted for in a model where strong phase are unknown (k=1)

33. 18 th November 2005 Guillaume Thérin 33 Lausanne –  measurements with 7D Neyman Confidence Region: r B (DK), r B (D*K), k.r sB  B (DK),  B (D*K),  B (DK*)   = 67°± 28°(stat.) ± 13°(syst. exp.) ± 11°(Dalitz model) D0K- D0K- D* 0 K - D 0 K* -  (deg) k.r sB (<0.75 @ 2  CL+ and no assumption) 2  CL 1  CL GGSZ – Combined results - B ±  D ( * ) K ±( * ) rBrB rBrB

34. 18 th November 2005 Guillaume Thérin 34 Lausanne –  measurements with Constraining  with B -  D ( * ) K ( * )- decays Introduction Gronau-London-Wyler method Atwood-Dunietz-Soni method Giri-Grossman-Soffer-Zupan method Combination

35. 18 th November 2005 Guillaume Thérin 35 Lausanne –  measurements with  (deg) 1-CL  = GLW+ADS+GGSZ - Combination - B ±  D ( * ) K ±( * ) Sensitivity for all methods depends on r B GGSZ GLW+ADS B ±  D K* ± B ±  D* K ± B ±  D K ±

36. 18 th November 2005 Guillaume Thérin 36 Lausanne –  measurements with Constraining sin(  with B 0  D ( * )  decays

37. 18 th November 2005 Guillaume Thérin 37 Lausanne –  measurements with CP violation in B 0  D (*)  Large branching fraction for favoured decay (~3  x 10 -3 ) Small BR for suppressed decay (~10 -6 ) Small CP violating amplitude Favoured b  c decay Strong phase difference CKM angle    + Suppressed b  u decay Determines the sensitivity of the method r(D ( * )  ) ≡ r (*) = A(B 0 → D ( * )-  + ) ≈ 0.015 A(B 0 → D ( * )-  + )    + 

38. 18 th November 2005 Guillaume Thérin 38 Lausanne –  measurements with Time-dependent decay rate distributions Measurements of S + and S - determine 2  +  and  if r is an external input Experiment : tag the flavour of the B with lepton and kaon categories combined in a neural network Mixing-Decay interference P(B 0 → D ( * ) ,  t) 1 C cos(  m d  t) + S sin(  m d  t) P(B 0 → D ( * ) ,  t) 1 C cos(  m d  t) - S sin(  m d  t) ∞ ± ± ± ± ± ± ± C = 1 – r 2 1 + r 2 ≈ 1 l+l+ lepton tag K+K+ kaon tag (4s) Tag B Reco B K+K+ ++ zz K+K+ t  z/c z -s-s -- neglecting terms in o(r 2 ) S ± ≈ 2r sin ( 2  ±  ), |S ± | 0.03 < ~ ± ∞

39. 18 th November 2005 Guillaume Thérin 39 Lausanne –  measurements with Possible CP violation on the tag side Potential competing CP violating effects in B decays used for flavour tagging signal sidetag side Lepton tags Kaon and other flavour tags ’ + P(B 0 → D ( * ) -  ,  t) 1 + C cos(  m d  t) + sin(  m d  t) [± 2r sin(2  ) + 2r’ sin(2  ’)] ∞ Kaon tag : expect CP violation comparable to signal → Modified time distributions K+K+ Observables a, b, c K+K+ PRD68, 034010

40. 18 th November 2005 Guillaume Thérin 40 Lausanne –  measurements with B 0 →D*    : partial reconstruction results 18710 ± 270 lepton tags 70580 ± 660 kaon tags Lepton Tags Preliminary Signal Combinatoric BB Peaking BB Continuum DD Find events with two pions and examine the missing mass m miss Lepton Tags kaon Tags Mean value A CP = N(B 0 tag) - N(B 0 tag) N(B 0 tag) + N(B 0 tag) Preliminary hep-ex/0504035

41. 18 th November 2005 Guillaume Thérin 41 Lausanne –  measurements with B 0  D (*) ,D  full reconstruction results background Lepton tags, D*  final state B modeYieldPurity (%) DD 15635  13585.5  0.3 D*D* 14554  12693.0  0.2 DD 8736  10581.7  0.4  +  +  0, D +  K -  +  +, K s  + D *+  D 0  +, D 0  K -  +,K -  +  0,K -  +  -  +,K s  +  - - Reconstruct B 0 candidate using full decay tree:

42. 18 th November 2005 Guillaume Thérin 42 Lausanne –  measurements with Determination of r Simultaneous determination of sin(2  +  ) and r from time-evolution is not possible with current statistics  Need r as an external input Estimate amplitude ratios from B 0  D s (*)+  - using SU(3) symmetry SU(3) r(D  ) = 0.019 ± 0.004 r(D *  ) = 0.015 ± 0.006 r(D  ) = 0.003 ± 0.006 I. Dunietz, Phys. Lett. B 427, 179 (1998) Assuming several hypotheses for SU(3) : Assuming factorisation Neglect exchange and annihilation diagrams without any theoritical errors

43. 18 th November 2005 Guillaume Thérin 43 Lausanne –  measurements with |sin(2  +  )| > 0.64 @ 68 % C.L. |sin(2  +  )| > 0.42 @ 90 % C.L. - Combine partial and fully reco results for the a and c lep parameters |2  +  | = 90 o  43 o 68 % 90 % 30% theoretical error on r 100% theoretical error on r Interpretation of sin(2  ) assuming SU(3) Assign theoretical error on r(D*  ), r(D  ) and r(D  ) Bayesian approach Frequentist approach (Feldman-Cousins) 90 % CL 68 % CL www.utfit.org

44. 18 th November 2005 Guillaume Thérin 44 Lausanne –  measurements with Conclusion

45. 18 th November 2005 Guillaume Thérin 45 Lausanne –  measurements with Conclusion Measuring  at B-Factories: an impossible mission a few years ago GGSZ analyses give the best results The GLW method eliminates  constraints close to 90 0 All analyses are statistically limited or statistics are too low for most sensitive methods  GLW,ADS,GGSZ WA = (63 +15 -12 )º |sin(2β+γ)| BaBar >0.64 (@ 68 %CL) B -  D ( * ) K ( * )- (GLW, ADS, GGSZ) B 0  D ( * ) 

46. 18 th November 2005 Guillaume Thérin 46 Lausanne –  measurements with Backup Slides