Chunhui Chen, University of Maryland PASCOS CP Violation in B Physics Chunhui Chen University of Maryland The 12 th International Symposium on Particles, Strings and Cosmology September 12 th, 2006 Columbus, Ohio

Chunhui Chen, University of Maryland PASCOS Most recent Results from BaBar and Belle for Stringent Tests of the SM & Search for New Physics using CP Violation in B Physics

Chunhui Chen, University of Maryland PASCOS PEP-II for BaBar 391 fb -1 As of Aug. 18 th, 2006 KEKB for Belle 630 fb -1 KEKB + PEP-II Performances of Two B Factories Far beyond the design luminosities for both experiments  1 Billion BB pairs !!

Chunhui Chen, University of Maryland PASCOS Why Study CP Asymmetry 0ne of conditions to generate matter dominated Universe: Sakharov conditions (1967): Violation of charge conjugation C & parity P asymmetries Baryon number violation, e.g., proton decay Deviation from thermal equilibrium CP violation allowed in Standard Model (SM): Common origin as the quark mass and their mixing Spontaneous electroweak symmetry breaking due to Higgs coupling Probing the EW scale as well, complementary to other studies at energy frontier, e.g.: high P T Physics at Tevatron & LHC Excellent probe for new Physics beyond SM Constraint on the possible new Physics beyond SM

Chunhui Chen, University of Maryland PASCOS CKM Matrix & Unitarity Triangle  3x3 complex unitary matrix  4 free parameters 3 angles 1 phase, change sign under CP  complex phase: Origin of CP violation in SM weak eigenstates ≠ mass eigenstates, related by CKM matrix

Chunhui Chen, University of Maryland PASCOS Methods to search for New Physics  Direct search for Physics beyond SM: CP violation in mixing, CPT violation in B decay …  Compare sin2  in tree and penguin modes: B 0  J/  K s v.s. B 0  K s  (b  ul ) Radiative penguin decays B 0 d and B 0 s mixing  2 )  1 )  3 ) CP asymmetries in: b->ccs modes. E.g.: B 0  J/  K s, etc. CP asymmetries in: B  , , . CP asymmetries in: B  DK, D , etc.  Overconstarint of the unitarity triangle: Indirect constraint: V ub,  m d,  m s … (not in this talk) Direct Measurement of CKM angles using CP violation

Chunhui Chen, University of Maryland PASCOS  CPV through interference of decay amplitudes  (B  f) Direct CP Violation in B System Difficult to extract CKM information due to strong phase BaBar: hep-ex/ E.g.: B  K +  - /K -  + A CP =   A CP =   BaBar: ICHEP06

Chunhui Chen, University of Maryland PASCOS  CPV through interference between mixing and decay amplitudes Time-dependent CP asymmetry Mixing Induced CP Violation For simple case shown with single decay mechanism: S fcp =Im fcp and C fcp =0 S fcp directly related to CKM angles Theoretically clean way to extract CKM angles = ¡ A CP

Chunhui Chen, University of Maryland PASCOS Current Measurement of  (  1 ) More detail: talk in parallel session: A. Kreisel Reference: hep-ex/ ,hep-ex/ hep-ex/ , hep-ex/ hep-ex/

Chunhui Chen, University of Maryland PASCOS Interference of b  c tree decay with mixing CP Violation in Charmonium Modes Decay dominated by Single Tree diagram: C=0 and S=sin2  Theoretically clean way to measure sin2 

Chunhui Chen, University of Maryland PASCOS Measure sin2  B 0  (cc)K (*)0 Modes B 0  J/  K 0,  (2S)K S,  c K S,  c1 K S, J/  K *0 (    S   ) sin2  =0.710   C=0.070   sin2  =0.642   C=   B 0  J/  K 0 only CP-odd CP-even CP-odd

Chunhui Chen, University of Maryland PASCOS Combined Results hep-ex/ hep-ex/  sin2  : Consistent between Babar & Belle Precision measurement, error ~ 4%  C: Slight difference between BaBar and Belle More data needed to understand difference

Chunhui Chen, University of Maryland PASCOS B 0  D* + D*  Ks Time-dependent Dalitz analysis (T.Browder, A. Datta et al. 2000)  cos2  > 0 BaBar 94%CL (hep-ex/ ,model-dependent) B 0  D (*)0 h0 (D 0  K S  & h0 =  0 etc.) Time-dependent Dalitz analysis  cos2  > 0 Belle: 98.3%CL (hep-ex/ , accepted by PRL) BaBar 87% CL (hep-ex/ ) From sin2  to  : cos2  Measurement Sign of cos2  Solve  and  /2-  ambiguity

Chunhui Chen, University of Maryland PASCOS Current Measurement of  (  2 ) More detail: talk in parallel session: C. Chavez Reference: hep-ex/ ,hep-ex/ hep-ex/ ,hep-ex/ hep-ex/ ,hep-ex/

Chunhui Chen, University of Maryland PASCOS If Interference of suppressed b  u tree decay with mixing only: C=0 and S=sin2  3 rd component: sizable Penguin diagram CP Violation in Charmless Modes C  0 S  sin2  “Penguin pollution” can be removed by isospin analysis  Clean measurement of  [Gronau-London 1990]

Chunhui Chen, University of Maryland PASCOS  diff. btw. Belle and BaBar More data needed to solve the difference between BaBar a& Belle CP Violation B 0  +  - hep-ex/ hep-ex/ Mixing inducted CP violation observed: BaBar (3.6  ), Belle (5.6  ) Direct CP violation: BaBar (No Evidence), Belle (5.5  )

Chunhui Chen, University of Maryland PASCOS inputs B (  +  0 ) = (5.75  0.42) B (  +  - ) = (5.20  0.25)  B (  0  0 ) = (1.30  0.21) C (  0  0 ) =  0.35  0.33 S (  +  - ) =  0.59  0.09 C (  +  - ) =  0.39  0.07 inputs B (  +  0 ) = (5.75  0.42) B (  +  - ) = (5.20  0.25)  B (  0  0 ) = (1.30  0.21) C (  0  0 ) =  0.35  0.33 S (  +  - ) =  0.59  0.09 C (  +  - ) =  0.39  0.07 No stringent constraint obtained with  system alone Extract  with B 

Chunhui Chen, University of Maryland PASCOS Similar Isospin analysis approach to extract  with B  Branching fraction of B0  0  0 /B 0  +  - is smaller than B  Small penguin pollution Extract  with B  New  0  0 branching fraction Isospin triangle now closed (new  0  + )  constraint on  becomes less stringent.  need to solve multiple solution 2005 Now B (  +  - ) = (23.5  2.2  4.1)  B (  0  0 ) = (1.16  0.37  0.27)  B (  +  - ) = (23.5  2.2  4.1)  B (  0  0 ) = (1.16  0.37  0.27)  10 -6

Chunhui Chen, University of Maryland PASCOS Extract  with B  B0B0 B0B0   Interference  info. on strong phase difference (no constraint at 2  ) Dalitz + Isospin (Pentagon) analysis

Chunhui Chen, University of Maryland PASCOS consistent with a global fit without  Combined: BaBar(  /  /  )+Belle(  /  )

Chunhui Chen, University of Maryland PASCOS Current Measurement of  (  3 ) More detail: talk in parallel session: V. Azzolini Reference: hep-ex/ ,hep-ex/ etc

Chunhui Chen, University of Maryland PASCOS Interference of color-allowed and color-suppressed tree decays Effect depends on ratio of two diagrams Measurement of  (  3 )

Chunhui Chen, University of Maryland PASCOS Combined Results of  (  3 ) Not including the most recent BaBar & Belle ICHEP06 results: See Virginia’s talk in this conference for detail

Chunhui Chen, University of Maryland PASCOS Now: looking for New Physics as correction to CKM Overconstrained: growing set of independent measurements are consistent with CKM picture UT from CKM angle and indirect Constraints Preliminary: Including the most recent BaBar & Belle ICHEP06 results:

Chunhui Chen, University of Maryland PASCOS New B Factory milestone: Comparable UT precision from CPV in B decays alone Overconstrained: subsets of measurements can be used to test for new physics UT from CKM Angle Measurement alone Preliminary: Including the most recent BaBar & Belle ICHEP06 results:

Chunhui Chen, University of Maryland PASCOS Interference of color suppressed b  s Penguin decay with mixing Another implication of overconstrained: redundant approaches to same CKM parameter CP Violation in Penguin Modes Dominated by Single penguin diagram: C=0 and S=sin2  but ……

Chunhui Chen, University of Maryland PASCOS Possible New Physics Effect 3 theoretically-clean modes  Ks,  ’Ks, 3Ks “Internal Penguin” E.g.: SUSY contribution with new phases New physics in loops?

Chunhui Chen, University of Maryland PASCOS Theory tends to predict positive shifts (originating from phase in V ts ) Naïve average of all b  s modes sin2  eff = 0.52 ±  deviation between b  s penguin and b  c tree mode Naïve average of all b  s modes sin2  eff = 0.52 ±  deviation between b  s penguin and b  c tree mode More statistics crucial for mode-by-mode studies Combined Results Observation of CP violation in B 0  ’ K 0 S=+0.55  0.11  0.02 (BaBar, 4.9  ) S=+0.64  0.10  0.04 (Belle, 5.6  ) Measured sin2  eff in all b  s modes are smaller than the measured sin2  in b  c tree mode

Chunhui Chen, University of Maryland PASCOS CP Violation in Mixing W-W- W-W- B 0 mass eigenstate: If mass eigenstate  CP eigenstate (|q/p|  1): CP Violation Expected deviation in SM ~ Most recent results: |q/p|-1 = (-0.8  2.7(stat.)  1.9(syst.))  10 -3, BaBar PRL96 (2006) |q/p|-1 = (+6.5  3.4(stat.)  2.0(syst.))  10 -3, Babar hep-ex/ |q/p|-1 = (+0.5  4.0(stat.)  3.5(syst.))  10 -3, Belle Phys.Rev. D73 (2006)

Chunhui Chen, University of Maryland PASCOS Summary and Outlook UT constraint from direct measurement of CKM angles sin2  determined at 4% level in Charmonium modes cos2  determined to be positive with > 98% confidence  /  /  Precise  measurement feasible by combining  /  /  Precision ~ 10  at present, need more statistics Methods to extract  well established in experiment Current UT constraint agree with SM Sin2  eff in penguin mode ~ 2  deviated from SM expectation interesting hint? Need more statistics No evidence of CP violation in B mixing Consistent with SM expectation More data expected in next 2 years! The best of two B factories is yet to come ! More data expected in next 2 years! The best of two B factories is yet to come !

Chunhui Chen, University of Maryland PASCOS Additional Slides for Reference

Chunhui Chen, University of Maryland PASCOS V is unitarity  geometric representation: triangle in complex plane Im Re V i1 V * k1 V i2 V * k2 V i3 V * k3 There are 6 triangles Kaon UT Beauty UT flat n.b. these triangles are rescaled by one of the sides The Unitarity Triangle

Chunhui Chen, University of Maryland PASCOS Located at the Stanford Linear Accelerator Center PEPII B Factory at SLAC L = 1.21 x /cm 2 /sec

Chunhui Chen, University of Maryland PASCOS DIRC ( PID) 144 quartz bars PMs 1.5T solenoid EMC 6580 CsI(Tl) crystals Drift Chamber 40 layers Instrumented Flux Return Iron / Resistive Plate Chambers or Limited Streamer Tubes (muon / neutral hadrons) Silicon Vertex Tracker 5 layers, double sided strips e + (3.1GeV) e - (9GeV) Collaboration founded in 1993 Detector commissioned in 1999 BaBar Detector

Chunhui Chen, University of Maryland PASCOS e + source Ares RF cavity Belle detector L = 1.65 x /cm 2 /sec SCC RF(HER) ARES(LER) 8 x 3.5 GeV 22 mrad crossing angle ~1 km in diameter Mt. Tsukuba KEKB Belle since 1999 The KEKB Collider

Chunhui Chen, University of Maryland PASCOS K L  detector 14/15 layer RPC+Fe Electromagnetic Calorimeter CsI(Tl) 16X 0 Aerogel Cherenkov Counter n = 1.015~1.030 Si Vertex Detector 4-layer DSSD TOF counter 3.5 GeV e + Central Drift Chamber momentum, dE/dx 50-layers + He/C 2 H 6 charged particle tracking K/  separation B vertex Muon / K L identification ,  0 reconstruction e +-, K L identification 8.0 GeV e - Belle Detector

Chunhui Chen, University of Maryland PASCOS For exclusive B reconstruction, two nearly uncorrelated * kinematic variables are used: B candidate (energy, 3-momentum) and beam energy in  (4S) frame Signal at  E ~ 0  (  E)  MeV Signal at m ES ~ m B  (m ES )  2.6 MeV “Energy- substituted mass” Reconstruction of B Decays E.g.: B 0  J/  K S

Chunhui Chen, University of Maryland PASCOS Background Rejection Ratio of second-to-zero th order Fox-Wolfram moments (R 2 ): Angle of thrust axis of “rest of the event” wrt B candidate direction (  T ) E.g.: B decays Continuum

Chunhui Chen, University of Maryland PASCOS CP-side Flavor tag and vertex reconstruction 1.Fully reconstruct one B-meson which decays to CP eigenstate 2.Tag-side determines its flavor (effective efficiency  30%) 3.Proper time (  t) is measured from decay-vertex difference (  z) electron positron  (4S) resonance B1B1 B2B2 ++ -- K+K+ --  ++ -- K S/L J/   z ~ 260  m (BaBar) B0B0 B0B0 _ Principle of tCPV Measurement  = 0.56 (BaBar) (Belle) produces coherent B pair