Stephen L. Olsen, Univ of Hawai’iChinas workshop-2006 June 11-18, Beijing

Tau-charm physics at B

factories

馬 鵬

• Main purpose: Study CP violation in asymmetric e+e - (4S) BB

• Both experiments have far exceeded their design goals• Approx. 1 ab-1 integrated flux combined

BaBar and Belle

e- (8 GeV/c)

e+ (3.5 GeV/c)

Peak luminosity 1.081034 cm–

2s–1

Integrated luminosity 363 fb–

1

Peak luminosity 1.621034 cm–

2s–1

Integrated luminosity 602 fb–

1

B Factories are -charm factories

On

~5M charm particles/fb-1

ECM (GeV)

0.89 nb ~2M ’s/fb-1

-physics at B factories

• M

• Spectral functions– Non-strange & strange

• Rare decays

• Forbidden decays

m away from threshold

Lafferty Charm 2006

Precision measurements

79 fb-1

Strange spectral function

Belle

Path to world-best measurements of |Vus| and ms

Rare decaysHuge signals for decays

limits on decays

LFV decays,ℓ-ℓ-

ℓ+, etc

Lafferty Charm 2006

LFV limits from BaBar & BelleX10-7

Lafferty Charm 2006

constraints from limits

Lafferty Charm 2006

constraints from limits

Lafferty Charm 2006

Future for LFV decays

Charm physics

•Charmed particle spectroscopy

•Rare decays

•Form-factors

•DDbar mixing

Sources of charm at B-factories

D

c

d

u

q

D

D

• Continuum– D*-tagged– Recoil tags

• B decays

• Radiative return

c

c

Old new charmed-strange particles

BaBar BaBar

BDs DsJ decays are spin filters

BDsDsJ

J=0J=0 J=?; m=0

DsJ(2460)

DsJ(2317)J=0DsJ(2460)J=1

Belle

P –wave c-s mesons?

Broad D** states found by Belle

Masses coincide?

See tak by Dmitrasinovic @ Charm 2006

New new charmed-strange particles

DsJ(2860)D0K+

BaBar

Baryons, baryons, baryons..

Signal

c+ sideband

Feeddown from c(2880)+

cc++-- cc

++00 cc++++

ISOTRIPLET!

BelleBelle

Rare FCNC charm decaysRare FCNC charm decays

18Paul D. Jackson Charm 2006

FCNC decays only occur in loop diagrams in SM:

New physics can introduce new particles into loop Some models increase

BF(cull) to 10-6—10-5

No signal forFCNC charmdecays foundLimits on yieldsextracted withunbinned likelihood fits

Largest “signal”is ~1.5 in

c+pµ+µ– decays

D+e+e– D+µ+µ–

Ds+Ke+e– D

s+Kµ+µ–

c+pe+e–

c+pµ+µ–

Unblinded Mass DistributionsUnblinded Mass Distributions

Paul D. Jackson Charm 2006 24

Branching Fraction LimitsBranching Fraction Limits

26Paul D. Jackson Charm 2006

Improved limits in 17 modes, more than order magnitude in 12 modes

(preliminary)

Upper limits on BF (x10-6) at 90% CL

Ktag

D

mass-constrained vertex fits

e+ e-3.5 GeV 8 GeV

K

K

D0

slow

e/µ

D*-

„inverse“ fit

tag side

Recoil-tagged Charmed mesons

D*

signal side

additional primary mesonsIP

L. Widhalm Charm06

Form Factors – Comparison with Models

ISGW2 modellattice calculation modified pole model

D0 lD0 l

D0 lD0 l

pole mass (GeV)

Kl 1.82 ± 0.04stat ± 0.03syst

l 1.97 ± 0.08stat ± 0.04syst

simple pole

Kl 0.52 ± 0.08stat ± 0.06syst

l 0.10 ± 0.21stat ± 0.10syst

modified pole(poles fixed at theo. values)

fit results

f+(0)

Kl 0.695 ± 0.007stat ± 0.022syst

l 0.624 ± 0.020stat ± 0.030syst

Belle

L. Widhalm Charm2006

CLEO-c untagged with v-reconstruction

bcM

Decay Mode - Simple Pole |Vcd| f +(0) mpole

D0 ±e 0.146 ± 0.004 ± 0.003 1.87 ± 0.03 ± 0.01

D± 0e 0.152 ± 0.007 ± 0.004 1.97 ± 0.07 ± 0.02

Decay Mode - Modified Pole |Vcd| f +(0)

D0 ±e 0.142 ± 0.005 ± 0.003 0.37 ± 0.09 ± 0.03

D± 0e 0.151 ± 0.008 ± 0.004 0.12 ± 0.17 ± 0.05

Preliminary

f (q2 ) f (0)

1 q2 mpole2 f (q2 )

f (0)

1 q2 mpole2 1 q2 mpole

2 Simple Pole

ModelModified Pole

Model

D0→-e+ D0→-e+

2q

I Shipsey Charm2006

DDbar mixing using D*-tags

DDbar mixing limits

Covered by A Schwartz

Particles with hidden charm

Charmonium production in B decays

j=½

j=½

J = 0 or 1

Spectator model says Jcc= 0 or 1 shoulddominate exclusive BK(cc) decays.

charmonium states

All sub-open-charmthreshold states havebeen identified

Discovered at B factories

Allowed decays all have Bf~10-3

cK 0.9 x10-3

JK 1.0 x10-3

J/K* 1.4 x10-3

’K 0.7 x10-3

’K* 0.9 x10-3

c0K 0.6 x10-3

c1K 0.7 x10-3

J/K12701.8 x10-3

BK cc(J=2) still not seen

XYZ particles• X(3872)

– J/ in BKJ/

• Z(3930)– DD in DD

• Y(3940)– J/ in BK J/

• Z(3940)– DD* in e+e- J/ DD*

• Y(4260)– J/ in e+e- J/

Z(3931) DD at Belle

41 11 evts (5.5)

M=3931 4 2 MeV

208 3 MeV

sin4 (J=2)

Matches well to c2’ expectations

Z(3931) is most likely the c2’

3931

X(3940)

e+e-J/ + X

e+e-J/ + DD*

Seen in DD* but not DD; this implies c1’ or c”

but e+e-J/ +c0 not seen

Is the X(3940) the c”?

3940Mass is about

150 MeV too low

X(3872)

BK J/

M(J)

’J/

X(3872)J/

S.K. Choi et al PRL 91, 262001

C=+1 is establishedX(3872)J/ seen in:

Belle

&

M( looks like a (CDF)

X(3872)””J/ seen in Belle

angular analysis favors 1++ or 2 -+

X(3872) has no obvious cc assignment

3872

Masswidth way too smallAngular dist. wrong

c is allowed J/ is isospin forbidden

c”

2

MassJ/ way too smallc1’

Masswidth too smallAngular dist wrongc0’

Y(3940) in BK J/M≈3940 ± 11 MeV≈ 92 ± 24 MeV

S.K. Choi et al. (Belle)PRL94, 182002 (2005)

M(J/) MeV (Y3940 J/ > ~7 MeV (an SUF(3)-violating decay)

Is the Y(3940) the c1’ ?

Y(3940) J/ enhanced by FSI ?

Y

D

D*FSI

JIt seems strange (to me) that an SU(3)-violating

process can “short out” an SU(3)-allowed process

If the Z(3930) is the c2’ (which seems likely)the Y(3940) mass is too high for the c1’

Y(4260) /ISR Jee

J/ sideband

Well above DD & DD* threshold but wide & found in a suppressed

mode??

M=4259 8 MeV = 88 23 MeV

B. Aubert et al. (BaBar)hep-ph/0506081

Y(4260)

10.58 GeV

4.26 GeV

not seen in (e+e-hadrons)at Ecm =4.26 GeV

J.Z. Bai et al. (BESII)PRL 88 101802

BES

(e

+e

- h

ad

ron

s)

cc~5nb

CLEO-c results on the Y(4260)

58 12 pb

PRL 96 162003 (2006)

(Y4260)J/ > ~1.8 MeV>10x higher than what we are used to

DD** threshold in relation to the Y(4260)

4.26-mD

Is the Y(4260) a hybrid?Expect distortions of J/ line shape

DD1

No sign ofYDD** “turn-ons”

DD0*0 DD0’0

Summary• B factories are also -charm factories

• Sensitivity for rare and forbidden LFV decays probably better than at threshold region

• Many discoveries of new (& sometimes unusual) charmed and hidden-charm particles

謝 謝Thank you