EPS, July  Dalitz plot of D 0   -  +  0 (EPS-208)  Kinematic distributions in  c   e + (EPS-138)  Decay rate of B 0  K * (892) +  - (EPS-123) Victor Pavlunin Purdue University the CLEO collaboration EPS-2003, Aachen, Germany Searches for CP asymmetries in the:

EPS, July  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. CP violation in the Standard Model In the SM, the origin of CPV resides in flavor changing quark transitions (V CKM ):

EPS, July The CLEO II and II.V detector  Tracking system: SVX (3 layers) or Gas Vertex Detector, Vertex Detector, Drift Chamber (B=1.5T, Ar 2 +C 2 H 6 or He 2 +C 3 H 8 ) (  p/p ~ 0.6% for a 2 GeV track)  Time of Flight system S cintillating 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.

EPS, July CPV studies at CLEO Type of CPV DirectMixingInterference Bottom Yes No Charm Yes All results reported today are on searches for direct CP asymmetries  CESR is a symmetric ( ) GeV e + e – collider.  On  (4S),  B =  B  B c  B is ~30  m,  D =  D  D c  D is  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.

EPS, July A CP in the Dalitz plot of D 0   -  +  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.  A CP is predicted to be as large as 0.1% (F.Buccella et al., Phys.Lett.B 379, 249 (1996)).  E791 found strong evidence for  (500) in D +   -  +  + ( PRL 86, 770 (2001)). Does  (500) contribute in D 0   -  +  0 ?

EPS, July Event selection for D 0   -  +  0 (CLEOII.V data only)  Standard criteria on charged tracks and  0 ’s  Constrain D 0 and  slow to the beam spot  D 0 (  -  +  0 ) and D* + (  -  +  0  + slow ): GeV < M(D 0 ) < GeV MeV < Q – Q expected < 0.691MeV, where Q  M(D *+ ) - M(D 0 ) X p  P (D *+ ) / P (D *+ ) max > 0.7 D *+  D 0  + slow, D 0   -  +  0,  0  . The sign of   slow determines the flavor of the D 0. Signal yield: 1.1K events in the signal box, of which ~20% are background.

EPS, July The Dalitz plot of D 0   -  +  0

EPS, July Fit to the Dalitz plot of D 0   -  +  0  The likelihood function has the form  The matrix element is parameterized as  A CP across the Dalitz plot is obtained as

EPS, July All Preliminary Results for A CP in D 0   -  +  0 Resonance AmplitudePhaseFit Fraction + (fixed)0 (fixed)76.5±1.8±4.8 00 0.56±0.02±0.0710±3±323.9±1.8±4.6  0.65±0.03±0.04  4±3±4 32.3±2.1±2.2 Non res 1.03±0.17±0.3177±8±112.7±0.9±1.7  Systematic errors (on-going): Parameterization of efficiencies; Parameterization of background; Signal fraction; Event selection criteria. Fit fraction of  (500) is consistent with zero.  The results of a fit with no CPV assumed (systematic errors are included):  The integrated A CP across the Dalitz plot:

EPS, July 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 form a spin zero state). Due to this simplicity, the predictions of HQET for  - type baryons are more reliable than for mesons.  Four kinematic variables describe the decay sequence  c   e +,  p  + : t = q 2 /q 2 max, cos  , cos  W and .  The four-fold decay rate has the form: are helicity amplitudes containing the dependence on the form factors.

EPS, July Form factor predictions for  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 q 2 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 = f 2 /f 1 and M pole.

EPS, July 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

EPS, July ML fit for 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 A (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 for R=f 2 /f 1 and M pole :  Major systematic errors Background shapes in 4D, Feeddown from modes  c   Xe +, X  0, Background normalizations, Uncertainties intrinsic to the fitter M(D s * (1 - )) = 2.11 GeV

EPS, July  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. All Preliminary A CP in the kinematic distributions of  c   e + for = 0.67 GeV 2.

EPS, July A CP in the decay rate of B 0  K * (892) +  - (EPS-123)  In SU(3) symmetry limit:  Measuring and allows the extraction of both  and the strong phase, .  CLEO measured ( PRL 89, (2002)):  This study extends the previous analysis and measures:

EPS, July Event selection in B 0  K * (892) +  -  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/  K 0 (or J/  0 ), J/    +  - Example:  Suppress background :. K * (892) + is reconstructed in two submodes: K * (892) +  K S 0  + and K * (892) +  K +  0.

EPS, July UML fit for B 0  K * (892) +  - and A CP  The likelihood function is given by Variables (plot on the right): M B, E B, 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 B 0  R *+ h –, where h – is  - or K -, R *+ can be any of the intermediate state resonances - K * (1430),  (770), or f 0 (980) ; and non-resonant (phase space) decays.  The fit is made for f j ’ s and ’s, where, for B 0  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 D 0  K -  + data and MC. K * (892) + (K S 0  - )  -

EPS, July Results for A CP in B 0  K * (892) +  -  Fit to 30 free parameters ( f j ’s and ’s) Yield for B 0  K * (892) +  -, K * (892) +  K S 0  + : Yield for B 0  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 A CP (Phys.Rev. D 68, (2003)): B 0  K * (892) +  -

EPS, July SUMMARY  A CP in the Dalitz plot of D 0   -  +  0 (EPS-208):, No evidence for  (500) is found.  Form Factors and Search for CPV in  c   e + (EPS-138):  Charge Asymmetry in B  K * (892) +  - (EPS-123):