EPS, July 2003 1

Dalitz plot of D0 - + 0 (EPS-208)

Kinematic distributions in c e+ (EPS-138)

Decay rate of B0 K*(892)+ - (EPS-123)

Victor Pavlunin Purdue University

the CLEO collaborationEPS-2003, Aachen, Germany

Searches for CP asymmetries in the:

EPS, July 2003 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. BBee ccee

EPS, July 2003 3

CPV studies at CLEO

Type of CPV Direct Mixing Interference

Bottom Yes Yes No

Charm Yes Yes Yes

All results reported today are on searches for direct CP asymmetries

CESR is a symmetric (5.3+5.3) GeV e+e – collider. On (4S),

B = B BcB is ~30 m,

D = DDcD is 120 - 320 m (assuming DD =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 2003 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 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 D0 - + 0?

EPS, July 2003 5

Event selection for D0 -+0 (CLEOII.V data only)

Standard criteria on charged tracks and 0’s

Constrain D0 and slow

to 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

D*+ D0 +slow , D0 - + 0 , 0 . The

sign of slow

determines the flavor of the D0.

Signal yield: 1.1K events in the signal box, of which ~20% are background.

EPS, July 2003 6

The Dalitz plot of D0 - +0

222

23 0

0256

1 dmdmM

md

D

EPS, July 2003 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

backgroundsignal

D

N

mmBF

N

MmmFL

),()1(

),( 222

220000

000

00

0000

00

D

i

D

i

D

i

iNRD

MeaMeaMea

eaM NR

2222

22

22

00

00

00

/ dmdmdmdmMM

MMA

DD

DDCP

EPS, July 2003 8

All Preliminary

Results for ACP in D0 - + 0

Resonance Amplitude Phase Fit Fraction

+ 1.00 (fixed) 0 (fixed) 76.5±1.8±4.8

0 0.56±0.02±0.07

10±3±3 23.9±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±0.31

77±8±11 2.7±0.9±1.7

)(09.007.0 09.001.0 sysCPA

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 ACP across the Dalitz plot:

EPS, July 2003 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 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 = q2/q2

max , cos, cosW and . The four-fold decay rate has the form:

are helicity amplitudes containing the dependence on

the form factors.

SpinHQSULorentzG _)2(

WH

EPS, July 2003 10

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 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 .

EPS, July 2003 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

EPS, July 2003 12

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 A328 547 (1993), in the measurement of form factors in DK*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=f2/f1 and Mpole:

Major systematic errors Background shapes in 4D,

Feeddown from modes c Xe+ , X0, Background normalizations, Uncertainties intrinsic to the fitter

5.0t

5.0t

5.0t

5.0t

5.0t

5.0t

cos cos

Wcos Wcos

12 / ffR

GeVM

R

sysstatpole

sysstat

10.007.013.2

,04.005.031.0

M(Ds*(1-)) = 2.11 GeV

EPS, July 2003 13

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

ACP in the kinematic distributions of c e+

Asysstat

cc

cc

cA 02.001.003.001.0

),( 22

AAOAAcc

cc

cc

cc

cc

cc

cA

)(02.0)(03.085.0

2

02/1

2

02/1

2

12/1

2

12/1

2

02/1

2

02/1

2

12/1

2

12/1

sysstat

HHHH

HHHHc

for <q2> = 0.67 GeV2.

c

c

EPS, July 2003 14

ACP in the decay rate of B0 K*(892)+ - (EPS-123)

In SU(3) symmetry limit:

Measuring and

allows the extraction of both and the strong phase, .

CLEO measured (PRL 89, 251801 (2002)):

This study extends the previous analysis and measures:

)(*0 ))892(( ieTPKBA)(*0

))892(( ieTPKBA)(~

22 AAB )(~ 22AAACP

665

* 10)216())892((

KBB

))892(())892((

))892(())892((*0*0

*0*0

KBBKBB

KBBKBBACP

EPS, July 2003 15

Event selection in B0 K*(892)+ -

Standard cuts on tracks and showers

0’s: P( 0) > 1.0 GeV

Beam constrained mass:

B candidate energy:

GeVpEMGeV BbeamB 3.52.522

BbeamB

B

EEE

MeVE

,)300(200

Veto some b c background: B D, D K; B J/K0(or J/0), J/ +-

Example:

Suppress background: .

qqee

8.0)cos( sph

K*(892)+ is reconstructed in two submodes: K*(892)+ KS0+ and K*(892)+ K+ 0.

EPS, July 2003 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.

candidates

1

components

1

variables

1

)1(i j k

ijkj

j PAfL

j

h

j

h

j

h

j

hj

NN

NNA

jA

K*(892)+(KS0

-) -

)10( 4 OAA

CP

EPS, July 2003 17

Results for ACP in B0 K*(892)+ -

Fit to 30 free parameters (fj’s and ’s) Yield for B0 K*(892)+ -, K*(892)+ KS

0+:

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)):

jA

10.0

08.033.034.0

*0 26.0))892((

KBACP

C.L.%90at 78.0;31.0))892(( *0 KBACP

B0 K*(892)+ -

CPA

6.49.36.12

2.29.11.6

EPS, July 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 in B K*(892)+ - (EPS-123):

)(09.007.0 09.001.0 sysCPA

GeVM

f

fR

sysstatpole

sysstat

10.007.013.2

,04.005.031.02

1

Asysstat

cc

cc

cA 02.001.003.001.0

10.0

08.033.034.0

*0 26.0))892((

KBACP

C.L.%90at 78.0;31.0))892(( *0 KBACP

EPS, July 2003 19

Additional slides

EPS, July 2003 20

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

jijji

i dVuJ )1(2

15

,

In the SM, the origin of CPV resides in flavor changing quark transitions (VCKM):

1)(

)()(

)(

j

ij

j

ij

jj

jj

ea

ea

fPA

fPA

1

2

2,

1212

*12

*12

2

00

i

M

iM

p

qPqPpP

0)(Im)(Im A

A

p

qCP