D 0 Mixing and CP Violation

B. Golob, Ljubljana Univ., JSI D0 Mixing and CPV 1 FPCP09, Lake Placid, May 2009

Boštjan GolobBelle & Belle II

University of Ljubljana, Jožef Stefan Institute

D0 Mixing and CP Violation

1. Phenomenology2. Measurements 3. Decays to CP eigenstates 4. Hadronic WS decays 5. t-dependent Dalitz analyses6. Average7. Constraints8. Outlook


1. Phenomenology

Time evolution flavor states ≠ Heff eigenstates: (defined flavor) (defined m1,2 and 1,2)

002,1 DqDpD

)0()( 2,12,12,1 tDetD ti

;2

; 2121

ymm

xttmi

etyix

Dp

qt

yixDtD 2000

2sinh

2cosh)(

|x|, |y| << 1

P0q1

q2 q1

P0q2

P0 = K0, Bd0, Bs

0 and D0

SM: |x|, |y| O(10-2)

D0 mixing is FCNC of u-type quarks

Decay time distribution of experimentally accessible states D0, D0

sensitive to mixing parameters x and y, depending on final state

2

000

2

)(Df

yix

p

qDfe

dt

fDdN t


1. Phenomenology

Oscillation frequency

Bs Bd D0

P(P0 P0)P(P0 P0)

Thus the system of the world only oscillates around a mean state from which it never departs except by a very small quantity Marquis de Laplace (1749 -1827)

x=26, y=0.15 x=0.8, y=0

x=0.01, y=0.01


D0: first two quark generations;CKM elements ≈ real;

using CKM unitarity:

below current exp. sensitivity; signals New Physics

1. Phenomenology

CP violationVcs

Vus*

D0

K-

K+

)(

0

0

0

0

0

0

2/1

)2/1(

),2

1(,2

1

,

fi

D

DM

MD

D

eA

RA

Df

Df

p

q

A

p

qA

Df

Df

RDf

Df

parameterization: RD ≠1: Cabibbo suppression

AD ≠0: CPV in decay AM ≠0: CPV in mixing ≠0 : CPV in interference

)(VV

VVVV -

udcd

ubcbuscs

3*

** 10~Imarg O


2. Measurements - general

Common methods

D*+ →D0s+

charge of s flavor of D0; M=M(D0s)-M(D0) background reduction

Experiments

p*(D*) > 2.5 GeV/c (or impact parameter) eliminates D0 from b → c

BelleBaBar

Cleo-c

CDF II


3. Decays to CP eigenstates

CP even final state;no CPV: CP|D1> = |D1> =1/1; K-+: mixture of CP states =f(1/1,1/2)

D0 → K+K- / +-

yxA

y

KK

Ky

CPVno

M

CP

sin2

cos

1)(

)(

S. Bergman et al., PLB486, 418 (2000)

Belle, PRL 98, 211803 (2007), 540fb-1

AM, : CPV in mixing and interference

exp. issues: - good S/N (tagged decays) - precise modeling of decay-t resolution needed

)%25.032.031.1( CPy

yCP=(1.24±0.39±0.13)%

BaBar, PRD78, 011105 (2008), 384fb-1


)%08.036.026.0( A

3. Decays to CP

eigenstatesCPV

intmixfdec

fCP

aaa

fDfD

fDfDA

)()(

)()(00

00

)%15.030.001.0( ABaBar, PRD78, 011105 (2008), 384fb-1

t-dependent

Belle, PRL 98, 211803 (2007), 540fb-1t-integrated:

t-dependent:

0sincos2

)()(

)()(00

00

CPVno

M xyA

KKDKKD

KKDKKDA

related meas. D0 → KS

-- CP= -1 (KS)-- CP= +1 (a0(980)KS)

CPCP

CPCP y

fy

f

1)1(

1' 11

)%52.061.011.0( CPy

exp. issues: un-tagged decays; worse t due to Ks ; comparison of topologically equal decays → reduced effects of resolution in <t>

’ ’’’’

m(K+K-)


4. WS decays

D*+ → D0 slow+ D0 → D0 → K+ -

DCS decays interference;

t

mixinterf

D

DCS

D etyx

tyRR

tDK

2

22

.

20

4

'''

)(

sincos'

sincos'

xyy

yxx

t-dependence to separate DCS/mixed

BaBar, PRL 98, 211802 (2007), 384fb-1

12

345

likelihoodcontours

3.9

Belle, PRL 96, 151801 (2006), 400fb-1

: unknown strong phase DCS/CF

CDF, PRL 100, 121802 (2008), 1.5fb-1

CPV allowed:separate D0 and D0 tags(x’2,y’,RD) → (x’±2, y’±,RD

±)

MM

MMM

DD

DDD RR

RRA

RR

RRA

results of similar accuracy

AD = (-21 ± 52 ± 15) ·10-3

exp. issues: - signif. background in WS; - accurate resol. f. param.; - stat. issues for x’2<0;


D0 →KS +-

different types of interm. states; CF: D0 → K*-+; DCS: D0 → K*+- ; CP: D0 → 0 KS

if f = f relative phases determined (unlike D0 → K+-);

t-dependence: regions of Dalitz plane → specific t dependence f(x, y);

5. t-dependent Dalitz

titi

titi

S

eemmp

q

eemm

tDKtmm

21

21

),(2

1

),(2

1

)(),,(

22

22

022

A

A

M

1,2=f(x,y); n.b.: K+-:x’2, y’

m±2 = m2(KS±),

t

access directly x, y

D0→f

D0→f

exp. issues: - model system.; - direct meas. x, y; - any f = f: sensitivity to x depending on a priori unknown strong phase variation

radpq

yx

)09.024.0(,86.0/

)%24.033.0()%,29.080.0(

30.028.0

09.010.0

29.030.0

14.010.0

16.013.0

Belle, PRL 99, 131803 (2007), 540fb-1


6. AverageAverage of results K+K-

K+-

KS-+ RM

2 fit including correlationsamong measured quantities

2/n.d.f.=25.3/20

http://www.slac.stanford.edu/xorg/hfag/charm/

(x,y)≠(0,0): 9.8 ;CP even state heavier and shorter lived;no CPV within 1

CP

V

uncertainty


8. Outlook

HFAG 2 fit

E. Barberio et al. (HFAG), arXiv:0808.1297& http://www.slac.stanford.edu/xorg/hfag/

1, 2, 3 @ 50 ab-1

50 ab-1

only KK/, K and Ks projected sensitivities included

expected sensitivity

)%3.01.0(

049.001.0

055.0919.0

)%001.0336.0(

6.45.24

)%062.0798.0(

)%087.0793.0(

D

D

K

A

rad

p

q

R

y

x


7. Constraints on NP constraints from mixing

21 NP models considered →17 with useful constraints; improved existing constraints; examples:

E. Golowich et al., PRD76, 095009 (2007)

D0 D0iL

l kRd~

iLl

kRd~

R couplings

kRd

m~

[GeV]

R SUSY:

xD=1.00%±0.25%constraint

4th generation fermion

mb’ [GeV]

|Vub’Vcb’|

xD=1.00%±0.25%constraint

xD=1.00%±0.08%constraint (50 ab-1)

xD=1.00%±0.08%constraint (50 ab-1)


::0,

:sincossincos

sincossincos

sincossincos

33

33

2,12,1

,

32

22

1

32

22

1

TCPd

dd

d

8. Outlook unexploited possibilities with B-factory data T-odd moments: D →KK

charmed baryon decays: c →, → p exp. issues: - unpolarized c; - p, p detector asymmetry

DCPV can be induced by FSI CPV

: (KK, plane);

exp. issues:-Br(D →KK) 1/2 Br(D →KK);- angular analysis


Conclusion

• D mixing and CPV are a unique handle to test FCNC of u-like quarks

• Important constraints on NP models from existing results (yet to be fully confronted with other experimental constraints)

• B-factories have not yet spoken the final word (only part of possible measurements done)

• Super-B factory can reach (x,y) 5x10-4, (ACP ~ x sin, AM y cos) 5x10-4

(possible evidence for NP)

there may be hidden treasures in charm physics....


Supplementary slides


Phenomenology more

n nD

Cw

Cw

D

Cw

D iEM

DHnnHD

MDHD

MiM

0110

02012 2

1

2

1)

2(

055

02

222**

2

2020 |)1()1(|

)(

4DcucuD

m

mmVVVV

GDHD

c

dsusudcdcs

FCw

short distance:

DCS SU(3) breakingG. Burdman, I. Shipsey, Ann.Rev.Nucl.Sci. 53, 431 (2003) |x| ~ O(10-5)

long distance:

absorptive part (real interm. states) ydispersive part (off-shell interm. states) x

D0 D0

K+

K-

I.I. Bigi, N. Uraltsev, Nucl. Phys. B592, 92 (2001);A.F. Falk et al., PRD69, 114021 (2004)

|x|, |y| ~ O(10-2)

D0 mixing: rare process in SM;possible contrib. from NP

x and y in SM 2nd order perturb.:

c

u

u

c

d, s, b d, s, b

W+

W-

D0 D0

Vci*

Vcj

Vuj*

Vui


continuum production

A) Experiments

* c

c

e+e- → (3770) → D0D0, D+D- (coherent C=-1 state); ~800 pb-1 of data available at (3770) 2.8x106 D0D0

3.5 fb-1 on tape(D0; pt>5.5 GeV,|y|<1)≈13 b50x109 D0’s

very diverse exp. conditions

d(D0)/dpt [nb/GeV]

(c c) 1.3 nb (~109 XcYc pairs)

Measurements – experim. more


K-+

Decays to CP eigenstates moreBelle, PRL 98, 211803 (2007), 540fb-1Fit

simultaneous binned likelihood fit to K+K- /K-+/+- decay-t, common free yCP

)(')'(/' tBdttteN

dt

dN t R

R : ideally each i Gaussian resol. term with fraction fi; : described by 3 Gaussians

N

i kikki tsttGwftt

1

3

10 ),,'()'( R

= 408.7±0.6 fs

event-by-event t

parameters of R depend slightlyon data taking conditions

trec-tgen/t


Decays to CP eigenstates more

yCP=(1.24±0.39±0.13)%

confirmation: BaBar, arXiv:0712.2249, 384fb-1

yCP currently most preciselymeasured param.

D0 → K+K- / +-

sincossin)1(cos

)cossin)(1(1,)cossin)(1(1

xyAxAyAA

yxAAyxAA

MDMff

ff

DMfDMf


)%08.036.026.0( A

3. Decays to CP

eigenstatesCPV

intmixfdec

fCP

aaa

fDfD

fDfDA

)()(

)()(00

00

)%15.030.001.0( A

Belle, PLB 670, 190 (2008), 540fb-1

BaBar, PRD78, 011105 (2008), 384fb-1

t-integrated ACP

meas =A + AFB + ACP

f

A : comparison of tagged/untagged

(D*+ →D0+),D0 →K-+ AFB: asymmetric f(cosCMS)

exp. issues: - meas. in bins of pD, cosD

due to A ( determined by NK

tag); - A

can be used in other meas.;

t-dependent

)%13.034.000.0( KKCPA

)%11.030.043.0( KKCPA

Belle, PRL 98, 211803 (2007), 540fb-1t-integrated:

t-dependent:

0sincos2

)()(

)()(00

00

CPVno

M xyA

KKDKKD

KKDKKDA

BaBar, PRL 100, 061803 (2007), 386fb-1

ACPKK ACP

|cosCMS|


3. Decays to CP eigenstates related meas.

D0 → KS

CP odd final state; (KS)= 1/2 > 1/1 =(K+K-)

exp. issues: - un-tagged decays; - worse t due to Ks - comparison of topologically equal decays → reduced effects of resol. in <t>

-- CP= -1 (KS)-- CP= +1 (a0(980)KS)

CPCP

CPCP y

fy

f

1)1(

1' 11

)'''('''

'''11

CPCPCP ffy

’ ’’’’

m(K+K-)

)%52.061.011.0( CPyBelle, preliminary, 600fb-1



methodBelle, preliminary, 600fb-1

D0 → Ks



Dalitz model CP=-1 Ks

CP=+1 a0(980)Ks

a0(1450)Ks

f0(980)Ks

f0(1370)Ks

f2(1270)Ks

flavour spec. K-a0(980)+

K+a0(980)-

K-a0(1450)+

Belle, preliminary, 600fb-1 D0 → Ks

model affects only fraction of CP=+1 states in individual mass interval; small model syst. uncertainty



syst. uncertainty on Belle, preliminary, 600fb-1

D0 → Ks

from MC (stat.)

data fluctuations


WS decays more C) WS decays (non-CP)

D*+ → D0 slow+ D0 → D0 → K+ -

BaBar, PRL 98, 211802 (2007), 384fb-1

Belle, PRL 96, 151801 (2006), 400fb-1

CDF: trigger: h+h- from second. vtx; NWS/NRS vs. t/ from M, M, imp. param.;

NWS/NRS

CDF, PRL 100, 121802 (2008), 1.5fb-1

NWS~13x103

12

34

CDF, PRL 100, 121802 (2008), 1.5fb-1


t-dependent Dalitz more

rad

pq

yx

)09.024.0(

86.0/

30.028.0

09.010.0

29.030.0

14.010.016.013.0

)%24.033.0()%29.080.0(

Belle, PRL 99, 131803 (2007), 540fb-1

D0 →KS +-

most accurate x

K*(892)+

K*X(1400)+

K*(892)-


t-dependent Dalitz more

2222

**2

20

4

)(t

yxAytAAxtAAA

e

tPffffffft

K

mmmmiiff

mmii

r

ir

i

mmii

r

ir

i

xteemmmmaaxtAA

emmeaemmaeamm

emmeaemmaeamm

r

r

11

)),(),(()(22

21

22

2111

*

),(22

211

1

22

211

22

21

),(22

211

1

22

211

22

21

22

21

22

2111

22

2111

22

2111

|),(|),(

|),(),(1),(

|),(),(1),(

ff

ff

ff

M|M|

M|A

M|A

BaBar, Lepton Photon 07, 384fb-1

D0 →KS0 BaBar, PRL97, 221803 (2006), 384fb-1


5. t-dependent Dalitz Belle, PRL 99, 131803 (2007), 540fb-1

D0 →KS +-

related meas. D0 →K+ -0

KK

KKxyyyxx

sincos''sincos''

BaBar, PRL97, 221803 (2006), 384fb-1

no mixing point 0.8% C.L.

radpq

yx

)09.030.0

28.024.0(,

09.0

10.0

29.0

30.086.0/

)%24.033.0()%,29.080.0(14.0

10.0

16.0

13.0

K: unknown strong phase shift DCS/CF

t

mix

f

interf.

ffff

DCS

f

etyx

A

txyAA

AtDK

]

||[

222

2

2200

4

''''||

)sin''cos''(||||

)(

exp. issues: - model system.; - direct meas. x, y; - any f = f: sensitivity to x depending on apriori unknow strong phase variation

separate WS/RS Dalitz distributions; t-distrib. analogous to D0 →K+ -;

RS t-integratedDalitz analysis;WS Dalitz analysis;


Average more Expected sensitivities from individual meas.

L = 5 ab-1 L = 50 ab-1 L = 5 ab-1 L = 50 ab-1

(x) 0.14% 0.10% 0.08% 0.05% KsKK, 0 total error :3(y) 0.11% 0.08% 0.06% 0.04% KsKK, 0 total error :3(yCP) 0.16% 0.11%(A) 0.12% 0.07%(ACP) 0.12% 0.07%(x’2) 0.11x10-3 0.09x10-3 0.13x10-3 0.10x10-3

x’2± stat. error •2 (y’) 0.20% 0.16% 0.23% 0.17% y’± stat. error •2(AD) 2.1% 1.7%(RD) 5x10-5 1.5x10-5 7x10-5 2x10-5

RD± stat. error •2

(|q/p|) 0.13 0.09 0.08 0.05 KsKK, 0 total error :30.12 rad 0.07 rad 0.07 rad 0.04 rad KsKK, 0 total error :3

i.e. assumingsens. same asin Ks

total errorscaled

for CPV allowed fit


Average more Projected sensitivities from average

)%0.12.0(

08.001.0

08.091.0

)%004.0336.0(

4.64.24

)%09.080.0(

)%12.080.0(

D

D

K

A

rad

p

q

R

y

x

)%0.12.0(

051.001.0

055.0910.0

)%003.0336.0(

7.45.24

)%06.080.0(

)%07.080.0(

D

D

K

A

rad

p

q

R

y

x

)%3.01.0(

049.001.0

055.0919.0

)%001.0336.0(

6.45.24

)%062.0798.0(

)%087.0793.0(

D

D

K

A

rad

p

q

R

y

x

)%26.01.0(

03.001.0

036.0914.0

)%001.0336.0(

7.36.24

)%045.0800.0(

)%055.0793.0(

D

D

K

A

rad

p

q

R

y

x

5 ab-1 5 ab-1, KsKK, 0 50 ab-1 50 ab-1, KsKK, 0

LHCb, 10 fb-1 (5 y): (x’2)~6x10-5, (y’)~0.9x10-3

(yCP)~0.05%main sensitivity on x, |q/p|, from t-dependent Dalitz analyses of Ks, 0, KsKK

+ assuming ACP=AD (AD) ~ 0.1%


Average more

0 1 2 3 4 5 [rad]

y’=

yco

s-x

sin

[%]

1.0

0.5

0

-0.5

-1.0

y’ measured

m

easu

red

(3770) →D0D0

constraints average direct meas. (fit w/o external input)

0 1 2 3 4 5 [rad]

cos

1

0

-1

D 0 Mixing and CP Violation

Documents

Transcript of D 0 Mixing and CP Violation