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L.Lista INFN Sezione di Napoli

L.Lista INFN Sezione di Napoli. Results of B A B AR experiment on CP violation and B physics. Outline. Experimental set-up CP asymmetries sin2 b sin2  eff B Mixing and lifetime Rare B decays Conclusions (Many topics will be skipped). (4S).

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L.Lista INFN Sezione di Napoli

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  1. L.ListaINFN Sezionedi Napoli Results of BABAR experiment on CP violation and B physics Luca Lista

  2. Outline • Experimental set-up • CP asymmetries • sin2b • sin2eff • B Mixing and lifetime • Rare B decays • Conclusions (Many topics will be skipped) (4S) Luca Lista

  3. center of mass energy  MU(4S) =10.58 GeV/c2 bg= 0.56 PEP-II at SLAC Low Energy Ring [e+, 3.1GeV] BaBar High Energy Ring [e-, 9.0GeV] The PEP-II B-Factory Luca Lista

  4. Integrated Luminosity 32 Million Y(4S) decays recorded • BaBar recorded: • 37.7fb-1 • 4.05 fb-1 off peak • Top luminosity: • 3.4x1033 cm-2s-1 • Design: • 3x1033 cm-2s-1 Luca Lista

  5. Electromagnetic Calorimeter 6580 CsI(Tl) crystals 1.5T solenoid e+ DIRC (PID) 144 quartz bars 11000 PMTs Drift Chamber 40 axial stereo layers e- Instrumented Flux Return 19 iron / 18-19 RPC layers Silicon Vertex Tracker 5 layers, 2-sided Si strips The BaBar detector Luca Lista

  6. A=(,) B=(1,0) C=(0,0) The Unitarity Triangle • Unitarity relations on matrix elements lead to a triangle in the complex plane • Quark mixing is described by the CKM matrix    1 Luca Lista

  7. B0 fCP B0 t d b B0 B0 W W t b d @Dt=0 B0 B0 F- F+ Dt(ps) CP violation at asymmetric B factory CP violation via mixing interference fCP eigenvalue  e-2ib For “golden” bccs modes: Luca Lista

  8. sin2b: Improvements w.r.t. run I • More data! • Added new modes • c1KS, J/K*0 • Improved reconstruction efficiency • Improved tracking • ~ +30% KS reconstruction eff. • Improved vertex resolution • New alignments • More elaborated vertex algorithm • Optimized KL selection taking into account the background CP asymmetry • Maximize (S+AB/ASB)2/(S+B), not S2/(S+B) Luca Lista

  9. All sin2b CP modes hCP = +1 IFR KL momentum not measured DE determined from B mass and beam energy constraints B0J/K0L N=129 (65% pur.) hCP = -1 B0J/K0S B0(2S)K0S B0cK0S N=724 EMC N=128 (56% pur.) Golden modes: ~30% higher efficiency than run 1: KS efficiency improved Luca Lista

  10. Fully reconstructed B flavor modes • Cabibbo favored decays: • B0D(*)-p+/r+/a1+ • B+ D(*)0 + , J/K+, (2S)K+ Luca Lista

  11. B01 partially reconstructed flavor tagged B02 fully reconstructed D*+  - or J/K0S e-e+ B1 = B0 B1 = B0 unmixedB0 B0 Dz Mixing and CP asymmetry of B0/B0 CP modes:FCP(Dt)  e-|Dt|/tB ( 1 hCPsin2b. sin Dmd Dt ) Flavour specific modes: Fflav(Dt)  e-|Dt|/tB ( 1 cosDmdDt ) mixedB0B0 or B0B0 Luca Lista

  12. Imperfect tagging and resolution D = 1-2w = dilution, w = wrong tag fraction R(Dt)= resolution function Imperfect tagging Imperfect resolution B0 B0 e-|Dt|/tB (1hCP sin2b  sin Dmd Dt) e-|Dt|/tB (1hCP Dsin2b sin Dmd Dt) e-|Dt|/tB (1hCP Dsin2b  sin Dmd Dt)  R(Dt) unmixed mixed e-|Dt|/tB (1cos DmdDt) e-|Dt|/tB (1 Dcos Dmd Dt) e-|Dt|/tB (1Dcos DmdDt)  R(Dt) Luca Lista

  13. Fitting Procedure • Unbinned maximum likelihood fit • Mistag and resolution: empirical distribution • fitted from data • fixed in the fit: md = 0.472 ps-1 (was extracted from the same fit in Run-I analysis) tB = 1.548 ps Separate for Run I & II Largest correlation With sin2b: 13% Luca Lista

  14. Flavor misid. measurement e w D=1-2w Q=e(1-w)2 s(sin2b) 1/(Q) Neural network mainly to recover unidentified leptons and use soft pions from D* Luca Lista

  15. sin2b result sin2b = 0.59 ± 0.14stat ± 0.05syst Luca Lista

  16. Comparison of different samples Submitted to Phys. Rev. Lett. On July 5 2001 Luca Lista

  17. 1s 2s Unitarity triangle sin2b = 0.59 ± 0.14stat ± 0.05syst Luca Lista

  18. Search for direct CP violation • Assuming more than one amplitude dominate the decay: || may be 1 • Only CP = -1 used • High purity, no assumption needed on CP of the background • No evidence found (none expected from SM) ||=0.93 ± 0.09 ± 0.03 Luca Lista

  19. Systematic errors • 0.03 from vertexing • 0.03 from tagging • 0.02 from background • Total 0.05 Luca Lista

  20. Dmdmeasurement preliminary Dmd= 0.519 ±0.020stat±0.016syst ps-1 Run I only Luca Lista

  21. Lifetime results B B0/B0 background Dt (ps) Dt (ps) t0 = 1.546  0.032(stat)  0.022(syst) ps t  = 1.673  0.032(stat)  0.022(syst) ps t0 /t = 1.082  0.026(stat)  0.011(syst) common resolution Luca Lista

  22. u u d d d d Charmless Hadronic Decays • Physics motivations • Significant penguin contribution • Direct CP violation studies • Measurement of  from time-dependent asymmetry + isospin analysis • Possible field for new physics… }p-(K-) Vud(s) d(s) W- Vub { b }p+ u B0 Cabibbo suppressed tree diagram }p-(K-) Vtd(s) W- d(s) Vtb }p+ { b u t B0 Penguin diagram Luca Lista

  23. Two body Branching fractions control sample: D*+D0, D0K-+ > 3 sigma Run I only p (GeV/c) Luca Lista

  24. CP violation in B0+-: sin2aeff • Neglecting penguin pollution: •  = f e-2i() = f e2i  C=0, S= sin2 • Considering penguin diagrams: • ||  1 • C  0, S= sin2eff = sin2  f (Penguin / Tree) • Extraction of sin2 requires the study of B000 and B000 • Fitted simultaneously with branching fractions • Dilutions and time resolutions taken from sin2b fit Run I + II expected ~0.3 preliminary ACP(K+p-) = -0.07  0.08  0.02 S = 0.03 +0.53-0.56  0.11 C  = 0.25 +0.45-0.47  0.14 Luca Lista

  25. Radiative Penguin: B  K* • Sensitive to top quark couplings • CKM matrix elements Vtd,Vts • Sensitive to New Physics • SUSY, Charged Higgs • No CP asymmetry in the Standard Model (< 1%) • Possible sources beyond SM Signal: B0  K*0, K*0  K+- Backgrounds: e+e-  qq  e+e-  qq  X 0 Luca Lista

  26. B0 K*0: yield and branching ratio • Nsignal = 139.2  13.1 events • Br(B0 K*0)= (43.9  4.1  2.7)  10-6 • Br(B Kl+l-) < 0.6  10-6 (90% C.L.) • Br(B K*l+l-) < 25.7  10-6 (90% C.L.) B0  K*0 K*0  K+p- Luca Lista

  27. BK, BK* • Penguin dominated Max Lik. Fit projections • B+K+=(7.7 +1.6-1.4  0.8)  10-6 • B+p+<1.4  10-6(90% C.L.) • B+K*+ =(9.7 +4.2-3.4  1.7)  10-6 • Possible measure of sin2b: • B0K*0 =(8.6 +2.8-2.4  1.1)  10-6 • B0 K0 =(8.1 +3.1-2.5  0.8)  10-6 Luca Lista

  28. Quasi 2-body and 3-body decays B+p+ = ( 6.6+2.1-1.80.7 )  10-6 B0K0 < 12 10-6 B+K+ = ( 70 85 )  10-6 B0K0 =( 42+13-114 )  10-6 B+K*+ = ( 22.1+11.1-9.2 3.3 )  10-6 B0K*0 = ( 19.8+6.5-5.61.7 )  10-6 B0K*0 p+ < 28  10-6 B+0K+ < 39  10-6 B+0p+ < 39  10-6 B+K+p+p- < 54  10-6 B+p+p+p- < 22  10-6 B0p =( 49  13 +6-5 )  10-6 B0a0(980)p Br(a0 p) = ( 6.7 +3.2-2.71.3 )  10-6 Potential for sin2a  First Observation  Luca Lista

  29. Search for direct CP violation Luca Lista

  30. B  D*D(*)K • Study of the bccs transition • Experimental inclusive estimate from from BDSX, (cc)X, CX, CX (ALEPH, CLEO) • Br(bccs) ~ 15.82.8 % • Theoretical calculation can’t determine this low value together with inclusive s.l. branching ratio (bcW) • Three-body B  DDK can contribute • Study of color suppressed modes (B+ D*+D*-K+) Color suppressed Color allowed Luca Lista

  31. B  D*D(*)K • Reconstructed decays: • D*+ D0p+ • D*0 D0p0 • D*0 D0g • D0 K-p+ • D0 K-p+p0 • D0 K-p+p-p+ • D+ K-p+p+ • Br(B0 D*+D0K+) = (0.280.070.05)10-2 • Br(B0 D*+D*0K+) = (0.680.170.17)10-2 • Br(B+ D*+D*-K+) = (0.340.160.11)10-2 • First observation of color suppressed mode other than B  (charmonium)X B0 (all modes) NS = 18021 B+ (all modes)NS = 11715 B+ D*+D*-K+ NS = 8.23.5 Luca Lista

  32. Conclusions • sin2 extracted from 37.7 millions of BB events sin2b= 0.59 ± 0.14stat ± 0.05syst • CP violation established at 4.1 level • First measurement of CP violation in B0 • High precision measurements of mixing parameter and lifetimes • High precision measurements of B decays branching fractions • Many newly observed decays • Most of the results are still statistically limited Luca Lista

  33. Backup slides Luca Lista

  34. J/ K* angular analysis J/ rest frame K* decay plane Channels withoutp0 f (costr, cosK*, tr) = f1|A0|2 + f2|A|||2 + f3|A|2 +f4Im(A||* A) + f5Re (A0* A||) + f6Im (A0* A) Channels withp0 • L=0,1,2 waves • Both CP even and odd amplitudes are present • Measurement of sin2b is possible from angular analysis Time dependent CP asymmetry dilution factor: D =1 – 2|A|2 = 0.680.10 Luca Lista

  35. B0 D*+D*- • Cabibbo suppressed decay • A measurement in bccd of CP violating time-dependent asymmetry can be performed from angular analysis • Possible penguin contamination • Measurement of sin2b independent from B0J/K0S • Significant deviations from B0J/K0S measurement of sin2b may be indication of new physics Tree diagram Penguin contribution • Branching ration measurement of B  D(*)+D(*)-: Luca Lista

  36. Signal box (38 events) Background sample (6.240.49 expected in signal box) B0 D*+D*- Br(B0D*+D*-) = (8.0  1.6  1.2)10-4 Luca Lista

  37. J/ +- J/ e+e- p*J/ < 2 GeV/c Inclusive Charmonium decays c J/, (2S), c b c • Inclusive J/branching ratio: Br(BJ/X) = (1.0440.013 0.028)10-2 Br(BJ/X dir.) = (0.7890.010 0.034)10-2 • Inclusive (2S)branching ratio: Br(B (2S) X) =(0.2750.020 0.029) 10-2 • (2S)l+l-branching ratio: (2S)  e+e- (7.8  0.9  0.8)10-3 (2S)  +- (6.7 0.8  0.7)10-3 • Inclusive cbranching ratios: Br(B c1 X) = ( 0.378  0.034  0.026 )  10-2 Br(B c1 X dir.)= ( 0.353  0.034  0.024 )  10-2 Br(B c2 X) < 0.2110-2 @ 90% C.L.= ( 0.137  0.058  0.012 )  10-2 W- B0, B- s, d X d, u Br((2S)  J/p+p-)assumed from PDG Luca Lista

  38. Exclusive B decays • Main motivation: • Channels are used for CP violation measurements • Kinematics selection: • Energy substituted mass • Independent on particle mass hypotheses • Energy difference in the center of mass B0J/ 0 First observation: B0c1 K*0 Luca Lista

  39. J/ production in continuum • First observation of J/ production in continuum • (4S) events with p*J/>2 GeV/c • Off-resonance events Angular distribution1+A cos2q* • A (all E*) = 0.250.19 • A (p*>3.5 GeV) l= 0.620.39 • Color singles prediction:   0.8 pb A  –0.8, • NRQCD (c.o.) prediction:   2.8 pb 0.6<A<1.0 Luca Lista

  40. Branching ratios results RUN 1: 22.7 MBB Luca Lista

  41. l+or l- e-e+ l+or l- N+–, –+ – N++, –– Asymmetry A(Dz)= N+ –, –+ + N++, –– Dz Dmdmeasurement: the di-lepton analysis Dmd= 0.499 ± 0.010 ± 0.012 ps-1 Luca Lista

  42. Semileptonic B decays • Determine the sign of the B from a sample of ~14000 fully reconstructed B B0D(*)-+, D(*)-+, D(*)-a1+, J/K*0 B- D(*)0+, J/K+, (2S)K+ • Lepton identified in the decay of the other B B+ B0 Mixing corrected Luca Lista

  43. bs, B0 mES for 0.6 <mhad < 2.0 GeV • Semi-exclusive study • Sum of exclusive modesK+np (n=1,2,3) Branching ratio measurementcoming soon… B0   • Theoretical exp.: ~ 10-8 • Br(B0) < 1.7 x 10-6 90% C.L. • PDG: Br(B0 ) < 3.9 x 10-5 90% C.L. (L3) Luca Lista

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