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Dalitz plot of D 0   -  +  0 (EPS-208)

Results on CP Violation from CLEO. Dalitz plot of D 0   -  +  0 (EPS-208) Kinematic distributions in  c  e +  (EPS-138) Decay rate of B 0  K * (892) +  - (EPS-123). Searches for CP asymmetries in the:. Victor Pavlunin Purdue University the CLEO collaboration

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Dalitz plot of D 0   -  +  0 (EPS-208)

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  1. Results on CP Violation from CLEO • Dalitz plot of D0   - + 0(EPS-208) • Kinematic distributions in c  e+(EPS-138) • Decay rate ofB0 K*(892)+ -(EPS-123) Searches for CP asymmetries in the: Victor Pavlunin Purdue University the CLEO collaboration EPS-2003, Aachen, Germany

  2. The CLEO II and II.V detector • Tracking system: SVX (3 layers) or Gas Vertex Detector, Vertex Detector, Drift Chamber (B=1.5T, Ar2+C2H6 or He2+C3H8) (p/p ~ 0.6% for a 2 GeV track) • Time of Flight system Scintillating plastic (t ~ 170ps) • Crystal Calorimeter CsI crystals(E/E ~ 2% for a 2 GeV photon • Muon chambers Proportional chambers at 3, 5 and 7 I • The size of the data sample is 13.7 fb-1. • 2/3 (1/3) is taken with CLEOII.V (CLEOII). • 2/3 (1/3) is taken ON (50 MeV OFF) (4S). • ~10M of and ~18M of events.

  3. CPV studies at CLEO • CESR is a symmetric (5.3+5.3) GeV e+e –collider. • On (4S), • B =B BcB is ~30 m, • D =DDcD is 120 - 320 m (assuming DD=1), • B <Vertex resolution < D • Time integrated asymmetries in B and D systems, and time dependent asymmetries in the D system are accessible. All results reported today are on searches for directCP asymmetries

  4. ACP in the Dalitz plot of D0   - +0 (EPS-208) • Interference of different intermediate resonances in the Dalitz plot makes amplitudes and phases of the resonances accessible. Expected contributions are from resonant decays through 0, + and -, as well as a non-resonant contribution. • ACP is predicted to be as large as0.1% (F.Buccella et al., Phys.Lett.B 379, 249 (1996)). • E791 found strong evidence for (500) in D+   -+  + (PRL86, 770 (2001)). Does (500) contribute in D0   - + 0?

  5. Event selection for D0   -+0(CLEOII.V data only) D*+  D0  +slow , D0   - + 0 ,  0  . The sign of  slow determines the flavor of the D0. • Standard criteria on charged tracks and  0’s • Constrain D0and slowto the beam spot • D0( - + 0) and D*+( - + 0  +slow): • 1.841 GeV < M(D0) < 1.885 GeV • -0.604MeV < Q – Qexpected < 0.691MeV, where Q  M(D*+) - M(D0) • Xp  P(D*+) / P(D*+) max > 0.7 Signal yield: 1.1K events in the signal box, of which ~20% are background.

  6. The Dalitz plot of D0   - +0

  7. Fit to the Dalitz plot of D0   - + 0 • The likelihood function has the form • The matrix element is parameterized as • ACP across the Dalitz plot is obtained as

  8. Results for ACP in D0   - + 0 • The results of a fit with no CPV assumed (systematic errors are included): • The integrated ACP across the Dalitz plot: Fit fraction of (500) is consistent with zero. • Systematic errors (on-going): • Parameterization of efficiencies; • Parameterization of background; • Signal fraction; • Event selection criteria. All Preliminary

  9. Form factor measurement and search for CPV in the decay c  e+(EPS-138) • In the heavy quark symmetry limit, particles with a heavy quark are subject to a larger symmetry group . The Lorentz structure of -type baryons is due to the polarization states of the heavy quark only (light quarks forma spin zero state). Due to this simplicity, the predictions of HQET for -type baryons aremore reliablethan for mesons. • Four kinematic variables describe the decay sequence c  e+,  p +:t = q2/q2max, cos, cosW and . • The four-fold decay rate has the form: are helicity amplitudes containing the dependence on the form factors.

  10. Form factor predictionsfor c  e+ • Traditional parameterization of the hadronic current: • HQET implies relations among form factors and reduces their number to two: • In order to fit the data, the q2 dependence of the form factors must be assumed. We follow the Korner-Kramer (KK) model (Phys.Lett. B 275, 495 (1992)) and assume the same dipole dependence for both form factors: • The fit is made for R = f2/f1 and Mpole .

  11. Yields and Estimation of kinematic variables • Event selection and background studies: • Estimation of kinematic variables (neutrino is missing): • kinematic constraints of the decay, • the thrust vector of the event, • the fragmentation function of c. ~3K of signal events and S/B=3.7

  12. ML fitfor form factors in c  e+ • The fitting method used in the analysis was first suggested in D.M.Schmidt, R.J.Morrison and M.S.Witherell, Nucl.Instr. and Methods A328 547 (1993), in the measurement of form factors in DK*l. • The following samples are used as separate components in the fit (10 different components): • c  e+for CleoII/CleoII.V (2 components) • c   e-for CleoII/CleoII.V (2 components) • c  e+ (2 components) • fake positron background (3 components with different momentum ranges) • fake background (1 component) • Simultaneous fit forR=f2/f1andMpole: • Major systematic errors • Background shapes in 4D, • Feeddown from modes c  Xe+ , X0, • Background normalizations, • Uncertainties intrinsic to the fitter M(Ds*(1-)) = 2.11 GeV

  13. ACP in the kinematic distributions of c  e+ • The fit results correspond to • If CP is conserved then . Therefore, a CP violating parameter can be defined as . • Fitting the charge conjugate states separately for and , and using the relation we obtain where correlations among systematic errors are taken into account. for <q2> = 0.67 GeV2. All Preliminary

  14. ACP in the decay rate ofB0  K*(892)+ -(EPS-123) • In SU(3) symmetry limit: • Measuring and allows the extraction of both  and the strong phase, . • CLEO measured (PRL89, 251801 (2002)): • This study extends the previous analysis and measures:

  15. Event selection in B0  K*(892)+ - K*(892)+is reconstructed in two submodes: K*(892)+KS0+ and K*(892)+K+ 0. • Standard cuts on tracks and showers • 0’s: • P( 0) > 1.0 GeV • Beam constrained mass: • B candidate energy: • Veto some b  c background: • B D, D  K; • B  J/K0(or J/0), J/  +- Example: • Suppress background: • .

  16. UML fit for B0  K*(892)+ - and ACP • The likelihood function is given by Variables (plot on the right): MB,EB, the Fisher discriminant, cos(B),dE/dx for the faster of the primary tracks (h- =  - or K - ) and Dalitz plot variables. Components: the signal, the continuum, the BBbar bckg, the B0 R*+h–, where h–is  - or K-, R*+can be any of the intermediate state resonances - K*(1430), (770), or f0(980); and non-resonant (phase space) decays. • The fit is made for fj’s and ’s, where , for B0  K*(892)+ - • PDFs are functions of the event location in the Dalitz plot (plot of the right) and are derived from the off-resonance data, the D0 K-+ data and MC. K*(892)+(KS0 -) -

  17. Results for ACP in B0  K*(892)+ - B0 K*(892)+ - • Fit to 30 free parameters (fj’s and ’s) • Yield for B0  K*(892)+ -,K*(892)+KS0+: • Yield for B0  K*(892)+ -, K*(892)+K+ 0: • Combined significance 4.6. • Major systematic errors • Dalitz PDF shapes • Fitting method • Interference among intermediate resonances • Final results for ACP (Phys.Rev. D 68, 017101 (2003)):

  18. SUMMARY • ACP in the Dalitz plot of D0   - + 0(EPS-208): • , • No evidence for (500) is found. • Form Factors and Search for CPV in c  e+(EPS-138): • Charge Asymmetry inB  K*(892)+ -(EPS-123):

  19. Additional slides

  20. CP violation in the Standard Model In the SM, the origin of CPV resides in flavor changing quark transitions (VCKM): • CPV in decay (direct): Time integrated asymmetries; but strong phases are hard to calculate. • CPV in mixing (indirect): Time integrated asymmetries (e.g., like-sign di-lepton events); expected to be small in the SM. • CPV in the interference between decays with and without mixing: Time dependent analyses; avoid hadronic uncertainties in some important cases.

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