APS Centennial

Centennial APS Meeting

Mats Selen, University of Illinois(speaking for the CLEO collaboration)

March 23, 1999

APS Centennial

This Presentation:

• New D0 mixing results – K mixing analysis (including lifetime)

(David Asner)– CP-even KK and lifetime results

(Tony Hill)

• Charmed Meson Spectroscopy– First observation of broad D1(j=1/2)

(Tim Nelson, Harry Nelson)

• B(c pK) absolute measurement– New method described– Preliminary results presented

(Dave Besson, Russ Stutz)

(Charge conjugation implied throughout)

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Our Detector:(CLEO-II & II.V)

Svx + HePr

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1996 1997 1998

32.3 pb-1

Our Accelerator(CESR)

9 fb-1

CLEO II.VIntegrated

Luminosity

DailyLuminosity

CLEO IItook 4.7 fb-1

prior to this

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Our Data:

On(2/3)Off(1/3)

This Presentation:

Mixing Analysis: 5.7 fb-1 CLEO-II.V (SVX)

DJ & c Analyses: 4.7 fb-1 CLEO-II

APS Centennial

0

0

*12

*12

*1212

0

0

22

22

D

D

iMiM

iMiM

D

D

t

00

00

DqDpD

DqDpD

H

L

1212

*12

*12

iM

iM

p

q

LHLH mmM

*

12*121212,

*12

*121212,

Re

Im

iMiMM

iMiMMm

HL

HL

Time evolution of D & D0 mesons

Decay eigenstates

Define

Where

Mixing Analysis:

APS Centennial

2y

Mx

What we are sensitive to in the K mixing analysis:

y

xyxRMIX

122

tan2

Where

D0 D0onshell

,KK…can be relatively

large in S.M.

D0 D0offshell

smallin S.M.

Window on New Physics

It will eventually be very important to disentangle “x” and “y”

CP eigenstate lifetime analysis will tellus about “y” independent of “x”

APS Centennial

RMIX =

)(

)(0

00

KDB

KDDBRMIX

D*+

D0

+

D0-

K+

D*+

D0

+

+

K-

“wrong-sign”

“right-sign”

But “wrong-sign” events can also come fromDoubly Cabibbo Supressed Decays (DCSD):

D*+

D0

+

-

K+

“wrong-sign”

Mixing in D0 K decays:

APS Centennial

D*+

D0

+

D0-

K+

Mixing

D*+

D0

+

-

K+

DCSD

1) Amplitudes evolve differently in time. 2) Amplitudes can interfere.

Can use timing information to help untangle Mixing from DCSD

Mixing vs DCSD:

Same initial & final states !• Bad news if this is all the info available• But theres more...

APS Centennial

The total “wrong-sign” rate is given by:

2

2cos2)( t

RtRRRetN MIX

MIXDCSDDCSDt

(Where t is measured in D0 lifetimes)

100% mixed100% DCSD

cos= 1cos= 0cos=-1

N(t)

D0 lifetimes

RMIX = RDCSD

RMIX / (RMIX+RDCSD)

(WS) (D0)

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Analysis uses excellent kinematic resolution tostop K-+ feedthrough, and relies on good Particle-ID to suppress backgrounds.

5.7 MeV

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RWS = (0.31 0.09 0.07) %

Systematic Errors

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CLEO-II 1

Aleph: RDCSD 1 RMIX 95% CL

E791Klv90%CL

E791 1

E691 90% CL

CLEO-II.5 1Preliminary

Results:

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Using Lifetime Info:

100% mixed100% DCSD

cos= 1cos= 0cos=-1

N(t)

D0 lifetimes

RMIX = RDCSD Exploit this info to limit RMIX

ws) = ( 0.650.4 (stat+sys) )x

D0)

APS Centennial

CLEO-II 1

Aleph: RDCSD 1 RMIX 95% CL

E791Klv90%CL

E791 1

E691 90% CL

CLEO-II.V 90% CLPreliminary

Mixing Results:

Limits have been calculated for all cos (ask me after)

APS Centennial

2y

Mx

What we are sensitive to in the K mixing analysis:

y

xyxRMIX

122

tan2

Where

D0 D0onshell

,KK…can be relatively

large in S.M.

D0 D0offshell

smallin S.M.

Window on New Physics

It will eventually be very important to disentangle “x” and “y”

CP eigenstate lifetime analysis will tellus about “y” independent of “x”

APS Centennial

CP-even Lifetime Analysis:

Look for (D0K-) (D0-K- K)

This is a direct measure of !(i.e. measure “y” independent of “x”)

Plan:Measure (D0K-)

(D0-) (D0K- K)

Both CP=+1Should have thesame lifetimes

D0K-D0-andD0K- Kare easy to distinguish kinematically

Don’t need particle-ID

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CP-even Yields:

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Lifetime Fits:

Use unbinned maximum likelihood fit toextract signal lifetimes:

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Extracting “y”:

Look for (D0K-) (D0-K- K)

12

Ky

Where + (-) are the CP even (odd) lifetimes,

and K = (+ + - )/2

Based on our present measurement:

y = -0.032 0.034or

-0.076 y 0.012 (90% CL)

CLEO II.V Preliminary

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Putting it all together

x

y

CLEO II.V Preliminary

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Future mixing prospects

CP odd eigenstatelifetime analysis

sneakpreview

Lots more data to analyze

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Charm Meson Spectroscopy

j=3/2

j=1/2

j=1/2

j=3/2

D1(j=1/2)D1(j=3/2)D2

*(j=3/2)

Previously not seen

Previously seen

D*+-

We search for

B- -

D0+

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• Analysis Technique– Partial reconstruction:

B- DJ0-; DJ

0 D*+-; D*+ D0

– Measure 4-momenta of .– Extract signal via 4-D Max Likelihood Fit

• Fitting Technique– 4 independent variables:

• helicity 2, helicity 3, azimuth ,D*

Fit parameters:Yields (3 resonant, 1 non-resonant)Mass and width of broad D1(j=1/2)Mixing and interference between resonances.Strong phases relative to D1(2420)

APS Centennial

Total Background

1+ d-wave 1+ s-wave 2+ d-wave

cos 3

vscos 2

vscos 2

vscos 1

cos 3

vscos 2

vscos 2

vscos 1

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Total background (see below)

D1(2420)0

D2*(2460)0

D01(j=1/2)

Fit Results

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1+ d-wave Weighted 1+ s-wave Weighted

2+ d-wave Weighted Background Weighted

Weighted Fit Components

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Preliminary Results

• Properties of D1(j=1/2)

MeV

MeVM

3626290

32102461101

79

41

34

With 5.7

significance

(second systematic error due to uncertainty modeling strong phases)

Spin-Parity assigned to 1+

Tests of JP favor 1+ over 0- (closest alternative).

Quark Model:

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B(c pK) Absolute• Why?

– One of the 4 measured quantities used to normalize all charm analyses

B(D0K-+),B(D+K-++),B(Ds+), B(cpK-+)

– Not well determined at present B(cpK-+) = (51.3)% PDG

• Our Technique (NEW):

e+ e-

c c

D*-

D -s

X e- e

p

c

Tag charm with one of these

pK-+

Baryon tag

Divide event into hemispheres

APS Centennial

Two versions:

c c D*-

D -s

X e- e

p

cpK-+

c c D*-

D -s

X e- e

p

canything

or

or

Triple correlation analysis (x2):

c cp

cpK-+

c c D*-

D -s

p

canything

anything

Double correlation analysis:

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Yield examples:

cpK-+

(same hemisphereas anti-proton tag)

D0K-+

(opposite hemispherefrom anti-proton tag)

(Double correlation analysis)

“numerator”

“denominator”

Apply efficiency correction and get answer...

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Sounds easy, but...Biggest Backgrounds/Corrections:

c c Dp

D N

Falsely increased denominator

Countc cp

D

anything

c c DD Falsely increased denominator

+ K-

Fake p tag

and correct

Study Kaon fake rate as a function proton momentum and correct (15% effect):

After correction,p momentum spectrumlooks OK.

APS Centennial

Preliminary Results

• Make the physics corrections mentioned on previous page (and other smaller ones):

• Make appropriate efficiency corrections.

B(cpK-+ )

Double correlation (4.9 0.5)%

Triple correlation (s tag) (5.2 1.3)%

Triple correlation (e tag) (5.6 2.5)%

Weighted average:

B(cpK-+ ) = (5.0 0.5 1.5) %

APS Centennial

Future ProspectsCLEO-III

• Several New Detector Components– RICH, Drift Chamber, Silicon

• New CESR cavities & IR– Lots more luminosity