expectation experiments rate asymmetries other approaches outlook

M. Selen, FPCP/02 1

• Expectation

• Experiments

• Rate Asymmetries

• Other Approaches

• Outlook

CP Violation in CP Violation in D Meson DecaysD Meson Decays

Mats Selen, University of Illinois

2002 FPCP Meeting, University of Pennsylvania

M. Selen, FPCP/02 2

0D

0Df( ) ≠ 0D

0Df

Indirect CPV:

Very small in charm since mixing is suppressed(i.e. good hunting ground for new physics)

( ) ≠ Direct CPV:

D f

11

ieA

22

ieA

D f

1*1

ieA

2*2

ieA

3

21*21

22

21

21*21 10

)(2)(2

)()()()(

cosAReAAA

sinAImAffffACP

M. Selen, FPCP/02 3

Since this decay isSingly Cabibbo Suppressed…

Direct CPV:

1) Consider D0 →

(same for K+KK+KK+K, , ,etc)

0Dc

u

u

d

u

d

W+

M. Selen, FPCP/02 4

0Dc

u

u

d

u

d

d,s,bW+

Direct CPV:

…we can modify it’stopology in a simpleway to get a penguin:

1) Consider D0 →

(same for K+KK+KK+K, , ,etc)

M. Selen, FPCP/02 5

0Dc

u

u

d

u

d

W+

0Dc

u

u

d

u

d

bW+

udcdVV *

ubcbVV *

differentweak

phases

differentstrongphases

are likely

23,

21

I

21

I

We have theingredients:

Expect ACP < 10-3

in most cases

Mats Selen

The reason that the tree diagram has delta-I = 1/2 and 3/2 is that the c quark has I=(0,0), u quark has I=(1/2,1/2) and d quark has I=(1/2,-1/2). Thus, the transition at the cWd vertex is delta-I = 1/2, the transition at the uWd vertex is delta-I = 1, hence their combination can be either delta-I = 1/2 or 2/3The penguin diagram diagram takes a c (0,0) to a u (1/2,1/2), hence is purely delta-I = 1/2

M. Selen, FPCP/02 6

2) Consider D+ → KS

(also KS, KSa1, K*[KS KS DSKSK[KS]K*Ketc)

Dc

d s

u

d

SKK 0

W+

d

Dc

d

SKK 0W+

s

d

u

d

CabibboFavoredDecay

DoublyCabibboSuppressedDecay

M. Selen, FPCP/02 7

D

SKK 0

CFDSKK 0DCSD

D

dCdKSS

SSCP sinsintanR

)KD()KD()KD()KD(A

22

Lipkin& Xing

M. Selen, FPCP/02 8

≤ 10-3

in SM(from data)

hopefully big(measurablein principle)

~5x10-2~1From CPV in

K0 system~ 3x10-3

D

SKK 0

CFDSKK 0DCSD

D

dCdKSS

SSCP sinsintanR

)KD()KD()KD()KD(A

22

New physics couldmake this much bigger

Lipkin& Xing

M. Selen, FPCP/02 9

)KD()KD()KD()KD(A

SS

SSCP

Bigi & Yamamoto, Phys. Lett B349 (1995)See Lipkin & Xing, Phys. Lett B450 (1999)

3x10-3 + new physics

So what?

• D+ → KS+, KS+, KSa1+…

• D0 → KS0, KS …

• Should be able to see K induced CPV with 107-108 reconstructed D events.

- This is in the ballpark for CLEO-c/Belle/BaBar

• New physics could make this asymmetry much bigger by increasing weak (and strong) phase differences.

- If seen, this can be studied using a suite of decays involving KL and KS in final state.

not suppressed (big BR)

M. Selen, FPCP/02 10

The usual suspectsThe usual suspects


CommentsComments Since D+ and D (and similarly D0 and D0) are not produced in equal numbers in FOCUS and E791,

these experiments normalize all asymmetries to some known Cabibbo favored mode.

e+e experiments need to worry about, A+, AFB

DDDDKKACP

KDNKKDND

For example:

where


These modes are “self-tagging” (no D* needed).

E791 D+ → K+K+, + ,K*(892)0+, ++

FOCUS D+ → K+K+, KSK+, KS+

DD++ Decays Decays


73710 ± 29268607 ± 282

D+→ D→

7355 ± 112

D→

6860 ± 110

D+→


5080 ±110

D+→S

5518 ±110

D→S

495 ±38

D+→S

454 ±42

D→S


1031± 44

1265± 48

474± 25

598± 28

D+→

23465± 183

28014± 201

D→

D+→ D→ D+→ D→


239± 18

291± 19

697± 42

851± 48

D+→ D→D+→ D→


-10-505

1015

K-K

+Pi+

KsP

i+

KsK

+(K

pp)

KsK

+(K

sP)

K-K

+Pi+

Phi

Pi+

K*K

+

PiP

iPiA

CP (%

)

stat

stat & systD± ACP

Summary

FOCUS E791

S S+

()

± 1.1 ± 0.5

S ± 1.5 ± 0.9

S ± 6.0 ± 1.5

SS ± 6.1 ± 1.2

± 2.9

± 3.6

± 5.0

± 4.2

S+

(S)

* All analyses statistics limited.* None are background free.


DD00 Decays Decays Use D* decays to tag D0 flavor:

E791 D0 → K+K, +, K++

FOCUS D0 → K+K, +

CLEO D0 → K+K, +, KS0, KSKS, 00

0* DD

fD 0

0D0D


KKD 0

333±21

KKD0

276±20

0D149±17

0D194±18

KD 0

7198±95

KD0

6075±87


KKD 0

1707±53

KKD0

1623±47

0D

606±31

0D

571±33

KD 0

19633±149

KD0

18501±144


KK

DD 00

2463±65

930±37

9099±151

0000 sKDD

00 DD

)(histogram

(points) 0

0

D

D


810±89 65±14

0000SS KKDD 0000 DD

)(histogram

(points) 0

0

D

D)(histogram

(points) 0

0

D

D


-15-10

-505

1015

K+K

-

Pi+

Pi-

KsP

i0

Pi0

Pi0

KsK

s

K+K

-

Pi+

Pi-

K+K

-

Pi+

Pi-

AC

P (%

)

stat

stat & systD0 ACP

Summary

CLEO FOCUS E791

S SS

± 2.2 ± 0.8

± 3.2 ± 0.8

S ± 1.3

± 4.8

S S ± 19

± 2.2 ± 1.5

± 3.9 ± 2.5

± 4.9 ± 1.2

± 7.8 ± 2.5

* All analyses statistics limited.* None are background free.


Other Promising ApproachesOther Promising Approaches

Look for CPV in Dalitz Plots: Analyze D and D samples separately Any differences in amplitudes & phases is an indication of

CPV. Work under way by several groups.

Examples from CLEO D0 → K+(Published last year). D0 → KS +(Preliminary results). D0 → +(soon…) D0 → S0(soon…).


D0

K

D0

K

Y

K

D0X

D0 K

Z

D0→


Resonance Fit Fraction Phase (770) 0.788 0.023 0 (fixed) K(892) 0.161 0.010 163 4 K(892) 0.127 0.010 0 4 (1700) 0.057 0.011 171 7 K (1430) 0.041 0.009 166 7

K (1430) 0.033 0.009 56 7

K(1680) 0.013 0.004 103 11 Non-res 0.075 0.011 31 7

We are sensitive to the amplitude and phase of something with BR ~ 10-3.

(Show Movie)


Fit D0 and D0 Dalitz Plots separately and look for asymmetries:

Find ACP = 0.031 0.086

DPdDD

DD

22

22

00

00

MM

MMACP

(Not an optimized ACP analysis)


Almost nobackground

D0→S

Fit D0 and D0 samples separately

0400300200202

1 ..ie..p

210

210

21

21

DDq

D

DDp

D

122 qp

writing

with

PRELIMINARY:


E791 and FOCUS Working on ACP analyses (for example Dalitz plots).

CLEO-c Still working on analyses using CLEO-II, II.V and III data. CLEO-c will turn on in about a year.

~30 million DD events (and new ACP search modes). ~ 1.5 million DsDs events

B Factories In the next 5 (?) years Belle and BaBar will accumulate

~100 times the integrated luminosity that CLEO has at the (4S). Improve on present CLEO limits by at least a factor of 10.

Hadron Machines CDF & D0 are getting into the game. BTeV (& LHC-b ?) could have 109 reconstructed charm events. COMPASS ? Others ?

BES

Outlook (is interesting)Outlook (is interesting)

E791

CLEO


Extra Slides…Extra Slides…


Observing this is evidence of CP

At the ”(3770)

e+ e

0D

0D

+

K+

e+e ” D0D0

JPC = 1

i.e. CP+

Suppose both D0’s decay to CP eigestates f1 and f2: These can NOT have the same CP :

CP(f1 f2) = CP(f1) CP(f2) (-1)l = CP

+ (since l = 1)

CPV through quantum CPV through quantum coherence at CLEO-ccoherence at CLEO-c

Sensitivity to this will be at the ~1% level


DD00→→AACPCP Fits Fits

expectation experiments rate asymmetries other approaches outlook

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