charm physics at b-factoriesmerlot.ijs.si/~golob/sola/babar_school.pdf · b. golob, ljubljana univ....

B. Golob, Ljubljana Univ. Charm Physics 1 BaBar School, SLAC, Oct 2009

Boštjan Golob

University of Ljubljana, Jožef Stefan Institute & Belle Collaboration

Charm Physics at

B-factories University

of Ljubljana

“Jožef Stefan”

Institute

BaBar Physics School,

SLAC, October 25-30, 2009


Outline

1. Generalities on charm of beauty

2. D0 Mixing

decays to CP states

WS hadronic decays

t-dependent Dalitz

CPV

3. Rare decays D0 l+l-

4. Ds leptonic decays

Ds mn

5. Spectroscopy

exotic states, Z+(4430)

6. Summary

7. Bonus material


Introduction

Dual role of charm physics

- experimental tests of theor. predictions (most notably of (L)QCD);

improve precision of CKM measurements (B physics);

example: leptonic decays of D mesons → decay constants,

tests of LQCD; Dr. Jeckyll

- standalone field of SM tests and search for new phenomena

(SM and/or NP);

example: mixing and CPV in D0 system Mr. Hyde


Introduction

Experiments

s(c c) 1.3 nb (~1.2x109 XcYc pairs)

continuum production * c

c

on resonance production

e+e- → U(4S) → B0B0, B+B-

s(BB) 1.1 nb (~109 BB pairs)

e+e- → y(3770) → D0D0, D+D-

(coherent C=-1 state);

~800 pb-1 of data

available at y(3770);

2.8x106 D0D0

(+ ~600 pb-1

at ECM=4170 MeV);

5.7 fb-1 on tape

s(D0; pt>5.5 GeV,|y|<1)≈

≈13 mb

75x109 D0’s

very diverse exp. conditions

We all live with the

objective of being happy;

our lives are all different

and yet the same.

Anne Frank (1929 -1945)

B-factory=charm factory


2

000

2

)(tDf

yix

p

qDfe

dt

fDdN t

D0 mixing

Time evolution flavor states ≠ Heff eigenstates:

(defined flavor) (defined m1,2 and 1,2)

00

2,1 DqDpD

)0()( 2,12,12,1

tDetD

ti

;2

; 2121

y

mmx

ttmi

etyix

Dp

qt

yixDtD 2000

2sinh

2cosh)(

|x|, |y| << 1

q2

P0 = K0, Bd0, Bs

0 and D0

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

D0 only P0 system with uplike quarks;

D0 mixing FCNC of uplike quarks

Decay time distribution of experimentally accessible states D0, D0

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

P0 q1

P0 q2

q1


D0 mixing

if mi = mj due to CKM unitarity:

no mixing

Phenomenology P0-P0 transition → box diagram at quark level

P0: any pseudo-scalar meson;

specific example of D0

c

u

u

c

d, s, b

d, s, b

W+ W- D0 D0

c

u

u

c

d, s, b d, s, b

W+

W-

D0 D0

Vci

Vcj

Vuj*

Vui* j

bsdji

iujcjciuiwk mmVVVVDHD

,,,

**00

|VcbVub*|<< |VcsVus*|, |VcdVud*|

assuming unitarity in 2 generations

0

55

0

2

222**

2

2020 |)1()1(|

)(

4DcucuD

m

mmVVVV

GDHD

c

dsusudcdcs

FC

w

m

m

G. Burdman, I. Shipsey,

Ann.Rev.Nucl.Sci. 53, 431 (2003) DCS SU(3) breaking

homework: estimate leading contrib. to box diagram for K0 and Bd,s

0 mixing

O. Nachmtann, Elem. Part. Phys., Springer-Verlag


n nD

C

w

C

w

D

C

w

D

ijD

D

jeffi

ij

iEM

DHnnHD

M

DHDM

M

M

DHDiM

0110

020

2

1

2

1

2

||)

2(

D0 mixing

Phenomenology

2nd order in pert. th.::

short distance:

|x| ~ O(10-5)

c

u

u

c

D0 D0 NP

common statement: mixing

with large x sign of NP;

Dn

nDnD

MEiEM

PViEM

11

long distance: contributes to y and x; y is affected by sum over

real intermediate states;

x also affected by

sum over off-shell states;

|x|, |y| ≤ O(10-2) I.I. Bigi, N. Uraltsev, Nucl. Phys. B592, 92 (2001);

A.F. Falk et al., PRD69, 114021 (2004)

D0 D0

K+

K-

D0 mixing is a rare process


D0 mixing

Bs Bd D0

P(P0 P0)

P(P0 P0)

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

x=0.01, y=0.01

Phenomenology

B. Spinoza (1632 -1677)

All things excellent are as difficult

as they are rare.


D0 mixing

Common exp. features

D*+ →D0s+

charge of s flavor of D0;

M=M(D0s)-M(D0)

(or q=M-m)

background reduction

D0 decay products vertex;

D0 momentum & int. region;

p*(D*) > 2.5 GeV/c

eliminates D0 from b → c

20

2

)(1tA

yix

p

qA

dt

fDd

efft


K+K- K-+ +-

Nsig 111x103 1.22x106 49x103

P 98% 99% 92%

D0 mixing Decays to CP eigenstates

CP even final state;

if no CPV:

CP|D1> = |D1> t=1/1;

K-+: mixture of CP states

t=f(1/1,1/2)

D0 → K+K- / +-

AM, : CPV in mixing and interference

(addressed later)

yxA

y

KK

Ky

CPVno

M

CP

t

t

sin2

cos

1)(

)(

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

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

M(K+K- ) ,

q=M(K+K- s)- M(K+K- )- M(),

st, selection optimized on MC


D0 mixing Belle, PRL 98, 211803 (2007), 540fb-1

Decays to CP eigenstates

c2/ndf=

1.084

(ndf=289)

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




K+K-/+-

and K-+ratio evidence

for D0 mixing (regardless of

possible CPV)

3.2 s

(4.1 s

stat. only)

+ )%25.032.0

31.1(

CPy




yCP=(1.24±

0.39±0.13)%


K+K-/+-

and K-+ratio evidence

for D0 mixing (regardless of

possible CPV)

3.2 s

(4.1 s

stat. only)

+ )%25.032.0

31.1(

CPy

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

yCP currently

most precisely

measured param.



D0 mixing

WS decays (non-CP)

D*+ → D0 slow+ D0 → D0 → K+ -

DCS decays interference;

sincos'

sincos'

xyy

yxx

t-dependence to separate DCS/mixed

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

: unknown strong phase DCS/CF

t

mixinterf

D

DCS

D etyx

tyRR

tDK

2

22

.

20

4

'''

)(

reconstruction

NWS=4030±90;

fit

R: sum of 3 Gaussians;

RS sample: t=(410.3±0.6) fs

WS

sample

DCS


1s

2s

3s

4s

5s

likelihood

contours

3.9s

D0 mixing

WS decays (non-CP)

Result

x’2, y’ region

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

evidence

for D0 mixing

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

95% C.L. (x’2, y’) contour

frequentist, FC ordering

RD = (3.03 ± 0.16±0.10 ) ·10-3

x’2 = (-0.22 ±0.33±0.21) · 10-3

y’ = (9.7 ±4.4±3.1) · 10-3

RD = (3.64 ± 0.17 ) ·10-3

x’2 = (0.18 ± 0.210.23) · 10-3

y’ = (0.6 ± 4.03.9) · 10-3

uncertainty includes syst. error

in y’=ycos-xsin,....

at Cleo-c


D0 mixing

t-dependent Dalitz analyses different types of interm. states;

CF: D0 → K*-+

DCS: D0 → K*+-

CP: D0 → r0 KS

if f = f populate same Dalitz plot;

relative phases determined

(unlike D0 → K+-);

D0 →KS +-


D0 mixing

t-dependent Dalitz analyses different types of interm. states;

CF: D0 → K*-+

DCS: D0 → K*+-

CP: D0 → r0 KS

if f = f populate same Dalitz plot;

relative phases determined

(unlike D0 → K+-);

t-dependence:

regions of Dalitz plane →

specific t dependence f(x, y);

titi

titi

S

eemmp

q

eemm

tDKtmm

21

21

),(2

1

),(2

1

)(),,(

22

22

022

A

A

M

sum of intermediate states:

1,2=f(x,y);

n.b.: K+-:x’2, y’ m±

2 = m2(KS±),

NRr i

NR

i

r eammBeamm

),(),( 2222A

t

access directly x, y

D0→f

D0→f


D0 mixing

t-dependent Dalitz analyses

Nsig= (534.4±0.8)x103

P 95%

Dalitz fit projections;

decay-t fit projection;

K*(892)+

K*X(1400)+

K*(892)- r/w

t [fs]

t = (409.9±0.9) fs

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

)%24.033.0(

)%29.080.0(

14.010.0

16.013.0

y

x

most sensitive

meas. of x 95% C.L.

region of

(x,y)


D0 mixing

D0: first two quark generations;

CKM elements ≈ real;

using CKM unitarity:

bellow current exp. sensitivity;

signals New Physics

CP violation Vcs

Vus*

D0 K-

K+

)(VV

VV

Df

Df-

uscs

ubcb 3

*

*

0

0

10~arg O

)(

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: Cabbibo suppression

AD ≠0: CPV in decay

AM ≠0: CPV in mixing

≠0 : CPV in interference


D0 mixing

)%08.036.026.0( A

CP violation

Decays to CP states

0sincos2

)()(

)()(

)()(

)()(

00

00

00

00

CPVno

M

intmix

f

dec

f

CP

xyA

KKDKKD

KKDKKDA

aaa

fDfD

fDfDA

tt

tt

with adec<<1:

)%15.030.001.0( A

Belle, PLB670, 190 (2008), 540fb-1

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

t-integrated

ACPmeas =A

+ AFB + ACPf

A : comparison of tagged/untagged

(D*+ →D0+),D0 →K-+

AFB: asymmetric f(cosqCMS)

t-dependent

)%13.034.000.0( KK

CPA

)%11.030.043.0( KK

CPA

Belle, PRL 98,

211803 (2007), 540fb-1

ACPKK ACP

AFBKK AFB

|cosqCMS| |cosqCMS|

|cosqCMS| |cosqCMS|

BaBar, PRL 100,

061803 (2007),

386fb-1


D0 mixing

CP violation

WS decays (non-CP)

separate D0 and D0 tags;

fit (x’2,y’,RD) → (x’±2, y’±,RD±);

DD

DDD

RR

RRA

AD = (23 ± 47) ·10-3

AM = (670 ± 1200) ·10-3

MM

MMMM

RR

RRA

yxR

2

22

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

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

consistent

consistent

consistent with 0

x10-3


additional free param, |q/p|, ;

rad

pq

)09.030.028.0

24.0(

09.010.0

29.030.0

86.0/

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


D0 mixing

Average of results K+K-

K+-

KS-+ RM

c2 fit including correlations

among measured quantities

c2/n.d.f.=

26.3/18

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

(x,y)≠(0,0): 10 s;

CP even state heavier and

shorter lived;

no CPV within 1s

CP

V

uncertainty

Don't keep mixing in these

other things. It only confuses.

K. Kinski (1926 - 1991)

n.b.: x(D0) ≈0.01; x(K0) ≈1; x(Bd) ≈ 0.8; x(Bs) ≈ 25;

x (0.98 +0.24 −0.26 )%

(26.4 +9.6 −9.9 )°

y (0.83 ± 0.16)%

Kππ (14.8 +20.2 −22.1 )°

RD (0.337 ± 0.009)%

AD (−2.2 ± 2.4)%

|q/p| 0.87 +0.17 −0.15

(−8.5 +7.4 −7.0 )°


constraints from mixing

21 NP models considered →17 with useful constraints;

improved existing constraints;

examples:

D0 mixing

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

D0 D0

iLlkRd

~

iLlkRd

~

R couplings

kRdm~

[GeV]

R SUSY:

xD=1.00%±0.25%

constraint

4th generation fermion

mb’

[GeV]

|Vub’Vcb’|

xD=1.00%±0.25%

constraint

Prediction is very difficult,

especially of the future.

N. Bohr (1885 - 1962)


constraints from mixing

21 NP models considered →17 with useful constraints;

improved existing constraints;

examples:

D0 mixing


D0 D0

iLlkRd

~

iLlkRd

~

R couplings

kRdm~

[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)



N. Bohr (1885 - 1962)


D0 l+l-

another FCNC;

BrSM(D0 m+m-) ~ 10-13

(including long distance contrib.)

(helicity supp., e+e- Br lower)

R SUSY:

Br(D0 m+m-) O(10-8)

Leptoquarks:

explanation of fDs discrepancy (see next slides)

Br(D0 m+m-) ~ 8x10-7

D0 rare decays homework: plot (short dist.) Feynman diagrams

for D0 l+l-

(hint: two amplitudes, one similar to (short dist.)

D0 mixing, other involves )

G. Burdman et al., PRD66, 014009 (2002)

D0 D0 i

l kd~

i2k

i2k i1k

i1k

kd~ i

lc

u

c

u

c

u kd

~ m

m

22k

21k

D0

relation to mixing

(if i=2, i.e. m contrib. in

mixing dominates)


I. Dorsner et al., arXiv:0906.5585


D0 l+l-

absolute Xc Br’s measurement

difficult @ B-factories

(normalization – scc; fragmentation)

relative measurement (D0 +-)

D0 rare decays

D0 +-

D0 m+m-

D0 e+e-

D0 e+m-

signal

region

# signal events,

, Br(D0 +-)

E. Won, EPS09,

http://belle.kek.jp/belle/talks/EPS09/won.pdf


D0 l+l-

systematic uncertainties

(, misidentification, fit,...) negligible;

L = 1 ab-1 (Belle) + 0.5 ab-1 (BaBar)

BrUL

exp = BrUL L0 / L

> O(100 GeV)

D0 rare decays

dm~

homework: Statistics: when and why does the U.L. scale

with integrated luminosity and when with L ?


Ds leptonic decays

Ds →mn

Q

q

P+

l+

n

fP

VQq

2

222

22

18

)(

P

PPQqF

SM

m

mmmfV

G

P

n

W+

(H+)

(Ds+ → tn): (Ds

+ → mn): (Ds+ → e+n)=

1:4x10-3:10-7

strategies:

fP |VQq|→ fP from LQCD |VQq|

fP |VQq|→ |VQq| from UT fit fP

H± contrib.;

...

Possible NP:

Exp. difficulties:

n in final state;

(absolute) measurement of Ds Br;

22

2

2

)tan1()()( nnH

PSM

m

mPP ll


Ds leptonic decays

D

e+ e-

n

Ds

µ

Ds*

tag signal

K

K

additional

particles

Kprim

full recon.

Ds →mn check of LQCD (fP) ?

Method:

inverse (recoil) reconstruction

D → Kn, n=1,3

relative charge (Kprim, D)/Ds*

right-, wrong-sign

inclusive Ds signal

(no m requirement)

efficiency depends on # primary particles:

nX = 3 (DDs*Kprim) + N

differences data/MC

M(Ds)=Mrec(DKprimX) recon. in recoil

M2(n)=M2rec(DKprimXm)

Ds → mn signal

Belle, PRL 100, 241801 (2008), 548fb-1


Ds leptonic decays Ds →mn Method fit data M(Ds) distr. with MC signal

in bins of nXrec;

bkg. from Wrong-sign

inclusive Ds normalization;

Method fully reconstruct tag side Ds,D

+,D0,D*+;

m,;

pn from pmiss with m(n,m)mDs;

signal in

M=M(mn)-M(mn) (~ mDs*-mDs);

exact Ds production in cc not known

normalization: Ds→

3

8

3

,

10)87.010.32(

i

iMC

Ds

Ds

i

rec

Ds NwN

Ds* →Ds

Ds → N=209399

D

e+ e-

n Ds

µ Ds* tag

Belle, PRL100, 241801 (2008), 548fb-1

BaBar, PRL98, 141801 (2007), 230fb-1


Ds leptonic decays Ds →mn Signal fit data M(n) distribution with MC signal

in bins of nXrec; bkg. from Ds → en

Belle, PRL100, 241801 (2008), 548fb-1

BaBar, PRL98, 141801 (2007), 230fb-1

Ds* →Ds

Ds → mn N=48955

816169

8

3

,

i

iMC

i

rec NwN m nm n

m nrec

Ds

rec

sN

NDBr

m n

m n

mn )(

Br(Ds → mn) =

(6.44 ± 0.76 ± 0.56) x10-3

Br(Ds →mn) =

(6.74 ± 0.83 ± 0.26 0.66) x10-3

dependence reduced (single track (m) recon.)

last uncertainty Br(Ds →)

fDs = (275 ± 16 ± 12) MeV

using |Vcs| = 0.9730 ± 0.0002 from overall

fit including unitarity (PDG)

fDs = (283 ± 17 ± 7 ± 14) MeV

Belle, PRL100, 241801 (2008), 548fb-1

BaBar, PRL98, 141801 (2007), 230fb-1


Ds leptonic decays Ds →mn Average of absolute

meas.;

fDs:

huge improvement in LQCD accuracy;

2.1 s difference;

agreement for fD+:

LQCD: 208 ± 4 MeV

exp.: 223 ±17 MeV

(but exp. error larger than for fDs)

HPQCD, UKQCD,

PRL100, 062002 (2008) LQCD

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

to do list:

confirm LQCD uncertainty;

reduce exp. uncertainty;

with L=1.5 ab-1

s(Br)/Br 9%

B-factories L=1.5 ab-1


Spectroscopy

Production

@ B-factories open and hidden

charm;

clean exp. environment;

various methods related

to different prod.

mechanisms;

rich harvest of previously

unknown states at

B-factories;

only one (“exotic”)

example discussed;

spectroscopy:

tests of QCD, bounding

q’s and g’s in hadrons

Vcb

Vcs* B

b c

q

c

s

q

Vcb

Vq1q2*

B

b c

q

q1

q2

q

c

c c

c

* e+

e-

* e+

e- X

e+

e- X

e-

e+

open charm

(Ds**, D**,...) colour suppressed;

hidden charm

(cc, charmonium-like...)

continuum

(double cc)

initial state radiation

(1-- states) two photon processes


Spectroscopy

Exotic states states other than q1q2, q1q2q3

not forbidden in SM;

exotic JPC (e.g. 0+-, 1-+, 2+-,...

forbidden for qq);

exotic decay modes (not possible

from qq);

strange properties (widths,...);

pentaquarks:

q1q2q3q4q5;

hybrids:

cc + g’s;

tetraquarks:

diquark-antidiquark, [cq][cq]

molecules:

M(cq)M(cq), loosely bound

mesons

...Life is like a box of chocolates, you never know...:

Forrest Gump (1994)


Spectroscopy

Z+(4430) B →(y’+)K;

y’ →ll, J/y;

Dalitz plot;

fit with Z+

& set of K*’s

M(y’+);

Z+(4430) signif.:

6.4 s

Belle, PRL100, 142001 (2008), 605 fb-1

Vcb

Vcs* B-

b c

u

c

s

u

d

d

d K0

[cu][cd] Z-

s

K*’s only

K*’s & Z+

MeVZ

MeVZM

)107()(

)4443()(

5674

14386

1319

1215


Spectroscopy

Z+(4430) B →(y’+)K;

detailed study by BaBar; angular distribution

of K vs. mK → description of mY (reflections);

satisfactory description (no need for Z+)

fit with K background and single resonance;

no stat. significant signal;

Belle/BaBar data not inconsistent run:

const int N_Bfact= 2; bool Found_It[N_Bfact]; string Balle=“BaBar Belle”; string::const_iterator ci; int i; for(ci=Balle.begin(); ci!=Balle.end(); ci++) { if(ci.findZ().fullL()) { cout<< “Z found in” << ci << endl; Found_It[i] = true; i++; } } if{Found_It[1] && Found_It[2]} cout<< “new form of matter found”;

residuals

ho

me

wo

rk:

Com

pile

the c

ode


Summary

Main experimental issues

Mixing and CPV

CP eigenstates

good S/N (tagged decays)

precise modelling of decay-t

resolution needed

WS hadronic decays

signif. background in WS;

accurate resol. f. param.;

stat. issues for x’2<0;

t-dependent Dalitz

model system.;

direct meas. x, y;

any f = f: sensitivity to x depending on

apriori unknow strong phase variation

CPV:

accurate estimate of detector

induced asymmetries

D0 l+l-

accurate description of reflection

statistically limited

Ds mn

method to perform absolute Br

measurement

with further work on syst. uncertainties

a measurement competitive to Cleo-c

possible

Spectroscopy

large number of “exotic” signals,

various methods

Dalitz analyses

Charm is... a way of getting the

answer yes without having asked

any clear question. A. Camus (1913 - 1960)


Summary

• D mixing and CPV, as well as some rare decays,

are a unique handle to test FCNC of u-like quarks

• Leptonic D(s) decays: tests show hints of discrepancy

(Dr. Jeckyll/Mr. Hyde)

• Important constraints on NP models from existing results

(yet to be fully confronted with other experimental constraints)

• Spectroscopy...may need extensions

• B-factories have not yet spoken the final word

(only part of possible measurements done)

• Super-B factory is clearly motivated also by charm physics

e.g. s(x,y) 5x10-4, s(ACP ~ x sin, AM y cos) 5x10-4

(possible evidence for NP)


Summary

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


Bonus material


D0 mixing

History observation of K0:

1950 (Caletch)

mixing in K0:

1956 (Columbia)

observation of Bd0:

1983 (CESR)

mixing in Bd0:

1987 (Desy)

observation of Bs0:

1992 (LEP)

mixing in Bs0:

2006 (Fermilab)

observation of D0:

1976 (SLAC)

mixing in D0:

2007 (KEK, SLAC)

(evidence of)

6

years

4

years

14

years

31

years

c quark

mass

t quark

mass

????

????


D0 mixing more

Time evolution

diagonal elem.: P0 P0

(including decays)

non-diagonal elem.: P0 P0

P0

q2 q1

P0

P0 = K0, Bd0, Bs

0 and D0

flavour states ≠ Heff eigenstates:

(defined flavour) (defined m1,2 and 1,2)

00

2,1 PqPpP

eigenvalues:

q

p

q

p

iMiM

iMiM

2,1*

12*

12

1212

22

22

),(2

1212

2,1

2,12,1

Mfim

)(4

2||4

2*

1212

2

122

12

2

2

Mm

Mm2121 , mmm

q1 q2


D0 mixing

Phenomenology only P0 system with down-quarks in loop;

D0 mixing FCNC of uplike quarks

|VcbVub*|<< |VcsVus*|, |VcdVud*|

assuming unitarity in 2 generations

222**

00

)( dsudcdcsus

wk

mmVVVV

DHD

0

55

0

2

222**

2

2020 |)1()1(|

)(

4DcucuD

m

mmVVVV

GDHD

c

dsusudcdcs

FC

w

m

m

more precisely:

G. Burdman, I. Shipsey,

Ann.Rev.Nucl.Sci. 53, 431 (2003) DCS SU(3) breaking

;)2

(1

2;)

2(

2 1212

211212

21

iM

p

qyiM

p

qmmx

mixing parameters:


D0 mixing

Phenomenology

if mi = mj due to CKM unitarity:

no mixing

P0-P0 transition → box diagram at quark level

),,( 2

,,,

22**

00

j

tcuji

iWujcjciui

wk

mmmVVVV

DHD

F

loop int., CKM unitarity

P0: any pseudo-scalar meson;

specific example of D0

c

u

u

c

d, s, b

d, s, b

W+ W- D0 D0

c

u

u

c

d, s, b d, s, b

W+

W-

D0 D0

Vci

Vcj

Vuj*

Vui*

j

bsdji

iujcjciuiwk mmVVVVDHD

,,,

**00

)(),,( 23

22

21

20

222 WjijiWjiW mOmmfmfmfmfmmmF

simplified treatment based on dimension:

O. Nachmtann, Elem. Part. Phys., Springer-Verlag

A.J. Buras et al., Nucl.Phys.B245, 369 (1984) for serious treatment see e.g.:


D0 mixing more

Time evolution

)sin(2)sinh(2

)cos()cosh(

)(1

**

22

22

0

xtAAp

qytAA

p

q

xtAp

qAytA

p

qA

dt

fPd

e

ffff

ffff

t

;2

; 2121

y

mmx

for easier notation:

t → t

decay rates:

Decay time distribution of experimentally accessible states P0, P0

sensitive to mixing parameters x and y,

P1,2 evolve in time according to m1,2 and 1,2: )0()( 2,12,12,1

tPetP

ti

00

2,1 PqPpP |P0(t)>, |P0(t)>

D. Kirkby, Y. Nir, CPV in Meson Decays, in RPP


D0 mixing more

CPV parameterization three types of CPV

iM

i

D

D

f

fiDD

f

f

iDD

f

fi

D

D

f

f

D

f

f

D

f

f

D

f

f

eA

p

q

eA

R

A

Ae

AR

A

A

eA

RA

Ae

A

R

A

A

A

A

A

RA

AR

A

A

)2

1(

21

;)2

1(

)2

1(;

21

21

;

*

*

*

*

RD ≠1 Cabbibo supp.

AD≠ 0direct CPV

AM≠ 0CPV in mixing

≠ 0CPV in interf.

- sign due

to relative sign of

Vus and Vcd;

22

2

22

*

*

)1(

)1)(1(

csud

uscd

f

f

VV

VV

A

A


D0 mixing more

Decays to CP eigenstates D0 → K+K- / +-

222

22

2

20

222

2

22

20

4)1(

1cossin

)1)(1(

1

)1(

1)(

4)1(

)1(cossin

1

11

)(

1;;;

tyx

Atyx

AAAA

e

tPf

tyx

A

Atyx

A

AA

e

tPf

AA

AAAAAff

MMDD

ft

D

M

D

Mft

D

f

f

ffff

tyxAAAAe

tPf

tyxAAAe

tPf

MDDft

DMft

cossin)1(21)(

)cossin)(1(1)(

2

20

2

20

to linear order:


D0 mixing more Decays to CP eigenstates

D0 → K+K- / +-

since AD<<1

tytyt

CP

t

CPfMftt

CPCP eeetyetPftPf

tyAtxAyAe

tPf

e

tPf

)1(2

02

0

22

20

20

)1()()(

]1[)sincos(1)()(

txAyAAAe

tPf

e

tPf

MDDftt sincos)1(1

)()( 2

20

20

if same procedure applied separately to D0 and D0 lifetime:

1/tf=t/(1+yCP); yCP=(t/tf)-1=y cos-Amx sin

tt

tt

tttt

sincossin)1(cos

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

xyAxAyAA

yxAAyxAA

MDM

ff

ff

DMfDMf


D0 mixing Decays to CP eigenstates

D0 → K+K- / +-

back

Fit

simultaneous binned likelihood fit to

K+K- /K-+/+- decay-t, common free yCP

)(')'(/' tBdttteN

dt

dN t Rt

t

R : ideally each si Gaussian resol. term

with fraction fi;

: described by 3 Gaussians

N

i k

ikki tsttGwftt1

3

1

0 ),,'()'( sR

t = 408.7±0.6 fs

event-by-event st

parameters of R depend slightly

on data taking conditions

trec-tgen/st

K-+

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


D0 mixing more

CP eigenstates CPV t-integrated CPV in D0 → K+K- / +-

A from comparison Auntag/Atag

=0

(strong int.) =0

(same for D0, D0)

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

method of


D0 mixing more

CP eigenstates CPV t-integrated CPV in D0 → K+K- / +-

A (p,cosq)

Belle, PLB670, 190 (2008), 540fb-1


D0 mixing more t-dependent Dalitz analyses

Dalitz model;

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

M signal

rnd slow

combin.

13 BW resonances, non-resonant contr.;

comb. bkg.: from M sideband

NRr i

NR

i

r eammBeamm

),(),( 2222A

test of S-wave contr. (f0, s1,2):

K-matrix formalism

Results (fit fractions, phases) in

agreement with

(measurement of 3)

Belle, PRD73, 112009 (2006)


D0 mixing more

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

Largest

systematics

model dependence [10-4]:

x y

-10.3 +0.1 K*0(1430) DCS/CF -15%

+ 6.9 -2.5 K*2(1430) DCS/CF -30%

-1.6 -0.9 K*(1410) DCS & CF -20%

-5.1 -4.1 (q2) const.

---------------------------------

+10 +6 Total model dep.

-14 -8

experimental:

x y

+7.6 -7.8 p* variation

-5.6 -5.7 Dalitz pdf for bkg. from

different t bins

-----------------------

+9 +8 Total experimental

-7 -12

ob

se

rve

d d

iscre

pa

ncy

from

inp

ut in

MC

statistical

uncertainty:

s(x)=29x10-4

s(y)=24x10-4


D0 mixing more


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

efficiency and resol. in M(

rnd s bkg.:

Prnd [(1-fw) M(m-2,m+

2,t) +fw M(m+2,m-

2,t)] R(t)

fw from fit to Q side band: fw= 0.452 ± 0.005

diff. w.r.t. fw=0.5 in systematic error

comb. bkg.:

Pcmb B(m-2,m+

2) * ([ (t) + Exp(t) ]R’(t)

parameters from fit to Dalitz and t distrib. of M(KS +- ) sideband

(systematics: Dalitz distrib. in different t intervals)


D0 mixing Constraints on NP

SuperB, L = 5 ab-1


x

x=2%

’12k’11k

GeVdmkR 300)

~(

TeVdmkR 1)

~(

D0 D0

iLl~

iLl~kRd

kRd

D0 D0

iLlkRd

~

iLlkRd

~

uncertain SM predictions for x, y;

measured values can impose constraints

on NP models parameter space;

e.g. R-parity violating SUSY;

existing constraints largely improved for

many NP models

R-parity violating

coupling const.

Approximate sensitivity

s(x) s(y) s(|q/p|) s()

0.1% 0.1% 0.1 0.1

LHCb, L = 10 fb-1

s(x’2) s(y’)

6x10-5 0.1%

x, y accuracy ~3x better than current WA;

sensitivity to CPV would cover range of

SM predictions



N. Bohr (1885 - 1962)


D0 mixing from CLEO-c

y(3770) →D0D0

at threshold D0D0 in C=-1 state

effective Br’s depending on

mixing param.:

y, RM=(x2+y2)/2, RDcos

S±: CP eigenstates

e-: Xen

fit to set of single and double Br’s

Br(D0D0 →fi/fj)

Br(D0 →fi)Br(D0 →fj)

Br(D0D0 →fiX)

Br(D0 →fi)

single D0

reconstr.

both D0

reconstr. )1(

)1(

)(

)(),(

2

2

221

yBrBry

eDBr

eDBreDSDBr

eSS

S

measured from ST rates

uncorrelated

production

uncorrelated

production

Cleo-c, PRD78, 012001 (2008), 281pb-1

(RWS=(K+-)/(K-+))


D0 mixing from CLEO-c

0 1 2 3 4 5 [rad]

y’=

yco

s-x

sin

[%

] 1.0

0.5

0

-0.5

-1.0

y’ measured

m

easure

d

y(3770) →D0D0

constraints

average

direct meas.

(fit w/o external input)

0 1 2 3 4 5 [rad]

cos

1

0

-1


Ds leptonic decays more Ds →mn projection

B factories with 2 ab-1

~4% uncertainty on fDs;

Charm-factory: syst. on Ds tags?

combined: test of LQCD to ~2-3%;

possible NP effects:

Cleo-c

Ds tags, 2.5%

L / fb-1 0.5 1.0 1.5 2.0

Cleo-c, PRD 76, 072002 (2007)

%5.1/

%1.7)(

0

LLf

f

Ds

Dss

Belle, PRL100,

241801 (2008), 548fb-1

M: NP mass

B.A. Dobrescu, A.S. Kronfeld,,

PRL100, 241802 (2008)


Spectroscopy

X(3872)

observed in B decays,

B →(J/y)K; charmonium-like;

well established state;

Vcb

Vcs* B

b c

q

c

s

q

K

Belle, PRL 91,

262001 (2003), 140fb-1

Mbc in 5 MeV bins

of M(+-J/y)

Belle,

hep-ex/0505038,

250fb-1 MeV

MeVMMM

MeVM

DDX

X

3.2

6.06.0

5.02.3871

00*)3872(

)3872(


MD+MD*

c’

J/y

c

cc0

cc1

cc2

y’ y”

hc

c”

hc’

cc1’

c2

y2 y3

Spectroscopy

X(3872)

properties

C=+1;

M() distrib., r-like;

(cc) →J/yr isospin breaking;

4-quark states:

c’’: ang. distr., M, ;

cc0’: ang. distr., DD;

cc1’: J/y

c2: c dominant, DD*;

cc2’: DD*;

no obvious cc candidate;

05.014.0)/(

)/(

y

y

JXBr

JXBr

102

1

)(2

1)(

2

1

2

1

II

dduudduucc

uucccc2’

CDF, PRL96, 1

02002 (2006), 360pb-1

Belle, hep-ex/0505037, 250fb-1

Belle,

hep-ex/0505038,

250fb-1

ang. distrib.:

JPC= 1++, 2-+ favoured;

more

isospin breaking


Spectroscopy

X(3872)

other possibilities

DD* molecule:

isospin breaking;

JPC=1++;

J/y favoured over DD;

exp. ratio ~ 0.1

E. Braten, M. Lu, PRD77, 014029 (2008);

see also E.S. Swanson, Phys. Rept. 429, 243 (2006)

for review

B+→ X(D0D00)K+

B+→ X(D*0D0)K+

MeVM X )9.07.04.3875(7.14.0

)3872(

MeVM X )5.01.3875(5.07.0

)3872(

last uncertainty: mD0;

main syst.: 0 calibration and signal shape

Belle, PRL97, 162002 (2006), 414 fb-1

BaBar, PRD77, 111102 (2008), 347 fb-1 410)/(

)( 000

y

JXBr

DDXBrR

Belle, PRL97, 162002 (2006), 414 fb-1


J=2 decays to DD*

suppressed by (p*)2L+1

with L=1,2;

1++ state favoured

more


Spectroscopy

X(3872)

other possibilities

DD* molecule:

prod. from B0 suppressed

compared to B+

(depending on model parameters);

tetraquarks: two mixed states,

[cu][cu], [cd][cd];

one produced mainly in B0,

other in B+ decays mass

difference;

also charged X+ [cu][cd],

no evidence so far;

Belle,

BELLE-CONF-0711,

605 fb-1

BaBar,

PRD77, 111101 (2008),

413 fb-1

M(J/y)

for B →XK K+

Ks

Ks

K+

MeVXBMXBM

XKBBr

XKBBr

)27.090.022.0()()(

10.024.094.0)(

)(

0

00

MeVXBMXBM

XKBBr

XKBBr

)4.06.17.2()()(

05.024.041.0)(

)(

0

00

L. Maiani et al., PRD71, 014028 (2005)

It is characteristic of wisdom

not to do desperate things.

H.D. Thoreau (1817 - 1862)


Spectroscopy more

X(3872)

B →KX (J/y):

B →Kcc1(J/y) calibration;

B →KX (J/y):

B →Ky2S calibration;

B →KX (J/y0):

13.6±4.4 evts.(4s)

no. of B’s in bins of M(J/y)


Belle,

BELLE-CONF-0711,

605 fb-1 no. of B’s in bins of M(0)

13.1±4.2 evts.(6.4s)

M(+-0)>750 MeV

3.04.00.1)/(

)/( 0

y

y

JXBr

JXBr



Spectroscopy more

X(3872)

tetraquarks:

predicted spectrum;

mass difference;

q: mixing angle

DD* molecule:

wave function fractions

MeVXMXM lhcos

27)()(

L. Maiani et al., PRD71, 014028 (2005)

back

410)/(

)( 000

y

JXBr

DDXBrR

E.S.Swanson, PLB588, 189 (2004)

Zi

binding energy


Spectroscopy

Z+(4430)

B →(y’+)K;

y’ →ll, J/y;

Dalitz plot;

K* veto;

M(y’+);

fit: BW + phase space;

signal stable in subsamples,

w.r.t. K* veto, etc.;

known S-, P- and D-wave K

resonances tried, cannot

reproduce the peak;

first charged charmonium-like

resonance;

Belle, PRL100, 142001 (2008), 605 fb-1

MeVZ

MeVZM

)45()(

)244433()(

1330

1318

N=121 ± 30

6.5 s

possibilities:

tetraquark, radial excitation of X+(3872)

(JP=1+; neutral partner?);

D*D1(2420) threshold effect;

D*D1(2420) molecule

(JP=0-,1-,2-;decays to D*D*?)

L.Maiani et al., arxiv:0708.3997

J. Rosner, PRD74, 114002 (2007)

C. Meng et al., arxiv:0708.4222


Spectroscopy more

Z+(4430)

S-, P-, D-wave interference: y’

K

q

16 GeV2

22 GeV2

M2(

y’)

+1.0

-1.0

co

sq

0.25 (4.43)2

GeV2

inte

rfere

nce

incoherent

cannot produce

a single peak

at cosq ~ 0.25

Belle, PRL100, 142001 (2008), 605 fb-1


SuperB more

back

energy frontier sesnitivity frontier

not to underestimate power of

precision measurements

Two approaches

Competitiveness

A. Roodman, JPS/DPF meeting, Hawaii 06


SuperB more 2

tree dominated

2

penguin dominated

NP

NP

Some physics motivation

different models for NP;

precise meas. of various

observables test

specifically for this mode:

SM expect. for sin21: 0 ± 2%

current sens.: 6% (b →sqq)

current lum.: 1.2 ab-1

needed: >10 ab-1

50ab-1 ΔS=0.23

B0→J/ψK0

B0→ K0


SuperB more Sensitivity

preliminary/

under construction !


SuperB more

More examples of physics

motivation

Complementarity

Super KEKB Physics

working group


SuperB more Proposed luminosity

Much smaller βy*

6.5(LER)/5.9(HER) → 0.21/0.37

Slightly increase beam currents

1.8A(LER)/1.45A(HER) → 3.6A/2.1A

Keep ξy

0.1(LER)/0.06(HER) → 0.09/0.09

LoI for SuperKEKB (2004)

Slightly smaller βy*

6.5(LER)/5.9(HER) → 3.0/6.0

Significantly increase beam currents

1.8A(LER)/1.45A(HER) → 9.4A/4.1A

Increase ξy

0.1(LER)/0.06(HER) → 0.3 or more

Proposed by P. Raimondi et al.

Decision expected in 2009

Target luminosity: 8×1035/cm2/s;

Continuous injection (succesful

experience of KEKB operation);

Options:

- High current

- Nano-beam



KEKB

design

KEKB achieved

(with crab)

SuperKEKB

High-Current

SuperKEKB

Nano-Beam

y* (mm) 10 / 10

6.5 / 5.9

(5.9 / 5.9) 3 / 6 0.26 / 0.26

x (nm) 18 / 18 18(15) / 24 24 / 18 2.8 / 2.0

sy(mm) 1.9 1.1 0.85 / 0.73 0.084 / 0.072

xy 0.052 0.108 / 0.056

(0.101 / 0.096) 0.3 / 0.51 0.08 / 0.08

sz (mm) 4 ~ 7 5 / 3 5 / 5

Ibeam (A) 2.6 / 1.1 1.8 / 1.45

(1.62 / 1.15) 9.4 / 4.1 3.6 / 2.1

Nbunches 5000 ~ 1500 5000 ~ 2000

Luminosity

(1034 cm-2 s-1) 1

1.76

(2.08) 53 80



Redesign the HER arcs to

reduce the emitance.

Two separate focusing

quads/each 2 beams

closer to IP;

Superconducting /

permanent magnets

New positron target /

capture section

Replace long dipoles

with shorter ones in HER.

Low emittance positrons

HER e+ 3.7 A

Low emittance gun

More RF /

modify RF systems.

Belle II

LER e– 2.1 A


Belle 2 more Higher background

radiation damage and occupancies

fake hits and pile-up noise in the ECL Improve performance

try better PID options

low p μ identification for b → sμμ efficiency

hermeticity → missing E “reconstruction”

Higher event rate

higher rate trigger, DAQ and computing

BELLE

BELLE-II

SC solenoid

1.5T

New DAQ and

computing

systems

CsI(Tl) 16X0

→ pure CsI (endcap)

Aerogel Cherenkov counter + TOF counter → “TOP” + Aerogel RICH

Si vtx. det. 4 lyr. DSSD → 2 DEPFET pixel lyrs. + 4 lyr. DSSD

CDC: Tracking + dE/dx → small cell + He/C2H6

remove inner lyrs.

m/KL detection

14/15 lyr. RPC+Fe

→ scintillator (endcap)


SuperB more A. Suzuki, KEK Director General, Inaugural meeting of Super Belle

charm physics at b-factoriesmerlot.ijs.si/~golob/sola/babar_school.pdf · b. golob, ljubljana univ....

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