CP violation at B-factoris Introduction  1 /   2 /   3 /  Vub, D mixing, Bs Conclusion Pavel Krokovny KEK, Tsukuba, Japan KEK

Unitarity triangle Using unitarity requirement: We need to measure all the angles to test SM.

CPV in Mixing B0B0 f CP B 0 AfAf AfAf 2 B0B0 f CP B 0 AfAf AfAf 2 Difference in decay rate for B 0 and B 0  CP Violation

Direct CPV in charged B Decays One rate asymmetry is not sufficient to extract physical parameters: measure A and A, but need A 1, A 2,  wk,  st CP violation through interference of decay amplitudes

KEKB and Belle KEKB Collider 3.5 GeV e + & 8 GeV e – beams 3 km circ, 11 mrad crossing angle L = 1.65 x cm –2 s –1 world record L dt = 740 fb Υ(4S) +off(~10%)

Event shape (m ES )  3 MeV (E) : mode dependent qq events (q=u,d,s,c) BB events  (4S) rest frame Event shape variables examples: Kinematics and event shape

 1 from the “golden” b  ccs mode -

Measuring cos2   B → D (*)0 h 0 with D 0 → K S  (same weak phase as B 0 → J/  K 0 ) cos2  consistently measured to be > 0! sin2  1 =0.75 ± 0.44 ± 0.22 cos2  1 =1.79 ± 0.53 ± 0.33 cos2  % CL cos  >0 solutions excluded: β = (21.3±1.0)°

CPV in B 0 → D + D -

sin2   from Penguin Decays no weak phase in b→(qq)s penguin decays –expect to measure S = sin(2   ) [just as in B → ψ K S ] –contributions from suppressed diagrams expected to be small (  sin(2   ) = sin(2   eff )  sin(2   ) ~ ) if new physics introduces weak phase in decay, we could measure something different than sin(2   ) new physics Standard Model New Physics NP weak phaseno weak phase from decay

sin2   in b  sqq Penguins No significant deviations from the WA from the value from the b  ccs modes: sin2   = 0.68±0.03 sin2   sin2  eff 1 eff HFAG advises extreme caution when interpreting this average (assumption of Gaussian errors not justified for all measurements)

Determination of  2 (  ) Time-dependent CP asymmetry: Tree: Penguin: Without penguin: Including penguin: Use isospin relations to estimate the penguin contribution: Neglecting EWP, h + h 0 (I=2)=pure tree Gronau-London, PRL, 65, 3381 (1990) Lipkin et al., PRD 44, 1454 (1991)

 2 (  ) Measurement using B    t (ps) PRL 78, (2007)

Sorting out penguin pollution Triangle analysis 6 observables 6 unknowns WA values  °±  °

B   isospin analysis WA values  ° <  2 <  ° B 0   +  – has 3 polarization states with different CP eigenvalues Fortunately, longitudinal polarization dominates  pure CP-even state No significant  0  0 signal  small penguin contribution

B   CP fit results PRD 76, (2007)

B →  Small penguins ! Dominantly longitudinally polarized ! Large branching fraction ! arXiv: v2 B 0 tag BABAR Time-dependent CP asymmetries in B 0 →     BaBar: 383 M BB

 with B →     With more data information on S 00 and C 00 will allow to resolve discrete ambiguities arXiv:

B 0  (  ) 0  Dalitz Analysis B0B0        B0B0 – Various (24) Patterns of Interferences  Information on Relative Phases Interference by B 0 B 0 oscillation + Interference Between  ,  ,   Dalitz tt

 Pentagon analysis  ° <  2 <  ° PRL 98, (2007)

 2 results:  B   B   B   ~90 o ±10 o

Determination of    Relative phase: ( B –  DK – ), ( B +  DK + ) includes weak ( γ/φ 3 ) and strong ( δ ) phase. If D 0 and D 0 decay into the same final state, B –  D 0 K – : Amplitude ratio: Possible D 0 / D 0 final states: CP eigenstates , KK) Flavor eigenstates (K  ) Three-body decays (K S  ) Gronau & London, PLB 253, 483 (1991) Gronau & Wyler, PLB 265, 172 (1991) Atwood, Dunietz, & Soni, PRL 78, 3257 (1997), Atwood, Dunietz, & Soni, PRD 63, (2001) Giri, Grossman, Soffer, & Zupan, PRD 68, (2003) Bondar, PRD 70, (2004)

Parameters are obtained from the fit to Dalitz distributions of D  K s π + π – from B ±  DK ± decays Dalitz analysis method Using 3-body final state, identical for D 0 and D 0 : K s π + π -. Dalitz distribution density: (assuming СР-conservation in D 0 decays) is determined from D *–  D 0 π –, D 0  K s π + π – decay  model uncertainty of the result A.Giri, Yu. Grossman, A. Soffer, J. Zupan, PRD 68, (2003) A.Bondar, Proceedings of the Belle Workshop, September (2002)

Dalitz analysis: sensitivity to the phase

Belle/Babar results on γ Fit parameters are x  = r cos(  φ3+δ) and y  = r sin(  φ3+δ) (better behaved statistically than r, φ 3 and δ) Belle/Babar measurements in good agreement Note: σ γ depends significantly on the value of r B Contours do not include Dalitz model errors rBrB 2γ2γ

Dalitz analysis (Belle) B   DK  B   D*K  B   DK*  Combined for 3 modes: φ 3 = 53° +15 3° (syst)9° (model) 8 ° < φ 3 <111 ° (2σ interval) r DK = 0.012(syst)0.049(model) CPV significance: 78% r D*K = 0.013(syst)0.049(model) r DK* = 0.041(syst)0.084(model) φ 3 = °(stat) φ 3 = °(stat) φ 3 = °(stat)

 from B  D (*)0 K, D 0  K S  (Babar) B -  DK - B +  DK + Dalitz distribution of selected B ± candidates 22 11 Stat Syst Model  =(92±41±11±12)°

Constraints of the Unitarity Triangle Estimated average with GLW, ADS, Dalitz and sin(2 φ 1 + φ 3 ) ~80 o ±30 o

Model-independent approach A.Bondar, A.Poluektov hep-ph/ ab -1 at SuperB factory should be enough for model-independent γ/φ 3 Measurement with accuracy below 2° ~10 fb -1 at ψ(3770) needed to accompany this measurement. A.Giri, Yu. Grossman, A. Soffer, J. Zupan, PRD 68, (2003) r B =0.2

Summary in pictures CPV angles CP-conserving quantities   

Summary in pictures

Summary φ 1 is measured with 1º accuracy. Still there is room for improvement. Remarkable progress in φ 2 measurement: accuracy of O(10º) is achieved using  and  Still limited by statistic - improvements in the future. The φ 3 remains the most difficult angle of the Unitarity Triangle to measure. Good perspectives with higher statistics since the theoretical uncertainties are very low. Model error can be eliminated using charm data: CLEOc/BES. No indication for a New Physics is found so far... Much more data is necessary  LHCb, Super B factory.

PEP-II and BaBar e-e- e+e+ 1.5T magnet Electromagnetic Calorimeter (EMC) Detector of Internally Reflected Cherenkov Light (DIRC) Drift Chamber (DCH) Silicon Vertex Tracker (SVT) Instrumented Flux Return (IFR) 3.1 GeV e + & 9 GeV e – beams L = 1.12 x cm –2 s –1 (June 28, 2006) L dt = 380 fb Υ(4S) +off (~10%)

Future plans of KEKB Next milestone –Accumulation of 1000 fb -1 (740 fb -1 at present) Near term plans –L = 2 x cm -2 s -1 Benefits of crab crossing Higher beam current (HER) > 1500mA with several reinforcements of vacuum components Search for better machine parameters –Beam emittance,  x *, x etc. Long-term future plan –SuperKEKB Major upgrade plan of KEKB Design luminosity: ~ cm -2 s -1 Not yet approved (Construction hope to start in FY 2009)

B  ρρ B 0   +  – has 3 polarization states with different CP eigenvalues Belle Fortunately, longitudinal polarization dominates, therefore, pure CP-even state BaBar (PRL 95, , (2005)): Belle (hep-ex/ ): cos  # of Events No significant  0  0 signal  small penguin contribution BaBar (PRL, 98, (2007)): 000 =(1.07 ±0.33 ±0.19) )(  BB

ADS method D. Atwood, I. Dunietz and A. Soni, PRL 78, 3357 (1997); PRD 63, (2001) Enhancement of СР-violation due to use of Cabibbo-suppressed D decays B –  D 0 K – - color allowed D 0  K + π – - doubly Cabibbo-suppressed B –  D 0 K – - color suppressed D 0  K + π – - Cabibbo-allowed Interfering amplitudes are comparable 

ADS method Belle results (357 fb -1 ) Suppressed channel not visible yet: Using r D =0.060±0.003, for maximum mixing ( φ 3 =0, δ=180° ): r B <0.18 (90% CL) r B <0.23 (90% CL) for B  DK r B <0.16 for B  D*K BaBar results (211 fb -1 )

GLW method M. Gronau and D. London, PLB 253, 483 (1991); M. Gronau and D. Wyler, PLB 265, 172 (1991) СР eigenstate of D -meson is used ( D CP ). CP-even : D 1  K + K –, π + π – CP-odd : D 2  K S π 0, K S ω, K S φ, K S η … for D 1 for D 2 4 equations (3 independent: ), 3 unknowns Additional constraint: СР-asymmetry:  A 1,2 of different signs

GLW averages D CP K * D * CP K D CP K

GLW method First evidence (3.4  ) for direct CP violation in B → DK decays

Dalitz analysis (Belle) Belle result (357 fb -1 ) PRD73, ±17 events 81±8 events 54±8 events B   DK  B   D*K  B   DK*  B-B- B+B+ B-B- B+B+ B-B- B+B+

Dalitz analysis: D 0  K s π + π – decay Statistical sensitivity of the method depends on the properties of the 3-body decay involved (For |M| 2 =Const there is no sensitivity to the phase θ ) Large variations of D 0 decay strong phase are essential Use the model-dependent fit to experimental data from flavor-tagged D *  D 0 π sample ( >2x10 5 events) Model is described by the set of two-body amplitudes + flat nonresonant term As a result, model uncertainty in the γ/φ 3 measurement

ρ-ω interference Doubly Cabibbo suppressed K * M (GeV 2 ) K s π – 2 D 0  K s π + π – decay model

Dalitz analysis (Belle) Fit parameters are x  = r cos(  φ 3 +δ) and y  = r sin(  φ 3 +δ) (better behaved statistically than ) are obtained from frequentist statistical treatment based on PDFs from toy MC simulation. B   DK  B   D*K  B   DK*  easier to combine results x – = y – = x + = – y + = – x - = – y - = – x + = y + = x – = – y – = – x + = – y + = –

sin(2φ 1 +φ 3 ) from B 0  D * π decay where Use B flavor tag, measure time-dependent decay rates: Decay : + B  D -  + B tag  B 0 CP violation

sin(2φ 1 +φ 3 ) result (211 fb -1 ) hep-ex/ result (357 fb -1 ) hep-ex/ Lepton tags, D*  final state New

sin(2φ 1 +φ 3 ) 90% CL 68% CL |sin(2  +  )| > 68 % C.L. |sin(2  +  )| > 90 % C.L. Combine partial and fully reco results and use the R parameters from SU(3) symmetry Frequentist confidence level |2  +  | = 90 o  43 o 30% theoretical error on r f |sin(2φ 1 +φ 3 )|> 0.44 |sin(2φ 1 +φ 3 )|> 0.52 R ~0.02 from New Br(B  D S (*) π)/Br(B  D (*) π)

D 0 -D 0 mixing