1 / 19

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

manjit
Download Presentation

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

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript


  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. 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.

  3. 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.

  4. 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

  5. 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?

  6. 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.

  7. The Dalitz plot of D0   - +0

  8. 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

  9. 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

  10. 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.

  11. 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 .

  12. 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

  13. 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

  14. 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

  15. 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:

  16. Event selection in B0  K*(892)+ - K*(892)+is reconstructed in two submodes: K*(892)+KS0+ and K*(892)+K+ 0. • Standard cut 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: • .

  17. 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 -) -

  18. 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)):

  19. 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):

More Related