The XYZ Mesons

Stephen OlsenU. of Hawai’i

&高能所 北京

Nankai University 天津 April 7,2008

Constituent Quark Model(CQM)

(& 6 antiquarks)

Mesons: q q

c: c+2/3

c: C-2/3

+ : s-1/3

s+1/3

s+1/3

c-2/3

u-2/3

b+1//3

u+2/3

- : b-1/3

S=1/3

b+1/3

t-2/3c+2/3

b-1/3

t+2/3

6 quarks

Baryons: qqq

u-2/3

d+1/3 s+1/3

u+2/3

d-1/3 s-1/3

Gell-Mann

Zweig

Fabulously successful

mesons qq

QCD suggests non-qq meson spectroscopies

Glueballs:gluon-gluon color singlet states

Multi-quark mesons:molecules: diquark-diantiquark:

qq-gluon hybrid mesons

d c

dc

c c

d c

dc

Caution

Searching for non-QPMhadrons is a risky business

小心

Remember the pentaquark

T.Nakano et al (LEPS) PRL 91 012002 (2003) 763 citations

+(1530)?

forget

You never can be sure:

or something else.

Is mother nature is smiling at you?

The XYZ mesons: candidates for non-qq states

c c

u cuc

4 quark candidates(from Belle)

“ hybrid” qq-gluon candidates(from Babar & Belle)

Charmonium is of particular interest

because it is an especially good system

to use to search for non-qq mesons

Primer on Charmonium

小学课本

Charmonium

r

mesons formed from c- and c-quarks

c-quarks are heavy: mc ~ 1.5 GeV 2mp

velocities small: v/c~1/4

non-relativistic QM applies

c c

QM of cc mesons

ErVmr

)(2

22

c cr

What is V(r) ??

“derive” from QCD

“Cornell” potential

~0.1 fm

G.S.Bali hep-ph/0010032

“confining”large distance

component

slope~1GeV/fm

1/r “coulombic”short distance

component

c cr

V(r)

2 parameters:slope & intercept

Charmonium spectrum

1-- Charmonium states

J/’

D-meson + anti-D meson mass threshold

”

“narrow”(~100KeV)

e+

e-

Directly accessible via e+e- annihilation

(e+e-hadrons)

“narrow”(~300KeV)“wide”(~25 MeV) ” DD decay

channel is openDD)25MeV

(4

040)

(4

160)

(4

415)

P-wave states Gamma energy spectrum from ’ X decays

Gaiser et al (Crystal Ball) PRD 34 711

accessible via E1 transitions from ’

23S1 (’)13P2 (c2) 17 keV

23S1 (’)13P1 (c1) 24 keV

23S1 (’)13P0 (c0) 24 keV

13P2 (c2) 13S1(J/) 420 keV

13P1 (c1) 13S1(J/) 290 keV

13P0 (c0) 13S1(J/) 120 keV

E1 Transition Partial width

Calculable from”1st prin

ciples”

Good agreement with

measurements

Hadronic transitions

(’J/) 70 keV“allowed”

(”J/) 50 keV“allowed”

(’J/) 5 keVSUF(3) violating

(’J/) 0.3 keVisospin violating

“reasonable” agreement between

measurement & th

eory

c.f. Kuang & Yan PRD 41 155

Recent results

13D1 13P1seen by CLEO hep-ex/0509030

(meas) = 75 18 keV(theor) 59~77 keV

11P1 found by CLEOhep-ex/0508037properties as expected

23P2 found by Bellehep-ex/0507033properties as expected

21S0 found by BelleS.K.Choi et al PRL 89 102001

properties as expected

The potential model for cc charmonium

mesons is robust and reliable

a cc meson has to fit into one of these slots:

If it doesn’t, it is a good candidate for a non qq meson

B-factories produce lots of cc pairs

0-+, 1- - or 1++

0-+, 0++, 2++

C =+ states

1- - only

Lots new on the “XYZ” particles

• X(3872)– J/ in BKJ/

• Z(3930)– DD in DD

• Y(3940)– J/ in BK J/

• X(3940)– e+e- J/X & e+e- J/ DD*

• Y(4260)– J/ in e+e- J/

• Y(4325)– +-’ in e+e-+-’

Y(4008)?

Y(4250)

Y(4370)

Y(4660)

X(3880)DD- e+e- J/ DD

X(4160)D*D*- e+e- J/ D*D*

Z+(4430)+ - BK+’

New Belle/BaBar results:(Summer 2007)

Status spring 2007:

confirmed by BaBar

updated by Belle

I’ll concentrate on recent results.

X(3872)

>300 citations

’ ’

’

X(3872)

X(3872)

X(3872)

X(3872) properties (PDG2007)

MD0 + MD*0 = 3.871.8 ± 0.4

MeV

M() looks like

2/dof = 43/39 (CL=28%)

kinematiclimit≈m

PRL 96 102002

CDFBelle

• Belle & CDF: JPC = 1++ most likely

What’s new with the X(3872)?

BaBar confirms Belle’s DD threshold enhancement

Mass is 3.8±1.2 MeV above WAvg X(3872)J/ mass;

(~3is this significant?

Both groups see a high mass value

Belle’s BKSX & BK±X comparison

M = 0.22 ± 0.90 ± 0.27 MeV

KS mode K± mode

“molecular” modelspredicted this to be <<1(Braaten et al PRD 71 074005)

“diquark-diantiquark” modelspredicted this to be 8±3 MeV

(Maiani et al PRD 71 014028)

Confirms an earlier BaBar result

Is there a cc slot for the X(3872)?

3872 M=3872 MeV is too low

Expect:rJ/>>Br(J/)Meas:r(J/)>>Br(J/)

1++(c1’)

cJ/ ispin forbidden D0D00 @ thresh.suppressed BKcc(J=2) suppressed

2-+(c2)

Y(3940) in BK J/

M≈3940 ± 11 MeV≈ 92 ± 24 MeV

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

M(J/) MeVM2(K) GeV2

M2(

J

) G

eV2

Y(3940) properties

Belle PRL94, 182002 (2005)

M(J/) MeV

(Y3940 J/) > 7 MeV~very large for charmonium

the Y(3940) mass seems toohigh for it to be the c1’

Confirmed by BaBar last summer

B±K±J/ B±K±J/

B0KSJ/

M2(K)

J)

ratio

Some discrepancy in M & ; general features agree

B.Aubert et al (BaBar) arXiv 0711.2047

Is there a cc slot for Y(3940) ?

Can M(c1’)>M(c2’)?c1’

Mass is lowc”

“ “ “ “c0

’

39403931

For any charmonium assignment, [Y(3940) J/ is too large.

Belle updates e+e-J/D(*)D(*)

D(*)

Use “partial reconstruction technique”

reconstructthese

J/

D(*)

“Recoil” D(*) undetected(inferred fromkinematics)

Continuum

e+ e

-

annihila

tion

e+ e-

J/D(*) recoil mass

J/

DD

J/

DD

*

J/

D*D

*

J/

DD

*

Partial reconstruction

reconstruct

Belle arXiv:0708.3812

M(DD*): Confirm X(3940)DD*

D-reconstructed D*-tag

D sidebands

6.0

Bg subtracted

M = 3942 +7 ± 6 MeV

tot = 37 +26 ±12 MeV

Nsig =52 +24 ± 11evts

-6

-15

-16

Previous values:M = (3943 ± 6 ± 6) MeV = (15.4 10.1) MeV< 52 MeV at 90%CL

PRL 98, 802001 (2007)

arXiv:0708.3812

Is there a cc slot for X(3940) ?

Mass is > M(c2’) &no c1 recoil seen

c1’

Mass is ~ 60 MeV low(if (3S) = (4040))c”

c0

’

39403931

Mass is > M(c2’) &DD decays not seen

Maybe the c”

M(D*D*)a new state at ~4160 MeV

D*-reconstructed + D*-tag

5.5

M = 4156 +25 ± 15 MeV

tot = 139 +111 ± 21MeV

Nsig =24 +12 ± 11evts

-20

-61

-8

arXiv:0708.3812

It has to have C=+; most likely 0-+,... possibly 0++

if 0++, why is it

not seen in DD?

A cc assignment for X(4160) ?

Mass is far too low(unless (4S)=(4160),but, then, where is (2D?))

c’’’

Mass is too high(if (3S)=(4040))

or too low(if (3S) = (4160))

c”

39403931

Can place either theX(3940) or X(4160),but probably not both.

4160

The 1-- states seen in ISR

e+e- isr Y(4260) at BaBar

233 fb-1

Y(4260)

BaBar PRL95, 142001 (2005)

~50pb

M=4259 8 +2 MeV

= 88 23 +6 MeV -6

-9

fitted values:

Not seen in e+e- hadrons

(Y4260 J/) > 1.6MeV @ 90% CL

X.H. Mo et al, PL B640, 182 (2006)

4260

4260

BES data

~3nb

peakY(4260)+J/pb

Huge by charm

onium

standards

J.Z.Bai et al (BES), PRL 88, 101802 (2006)

(e+e- hadrons)(e+e- +-)

“Y(4260)” at Belle (New) M=4247 12 +17 MeV

= 108 19 ±10 MeV -32

M=4008 40 +114 MeV

= 226 44 ±87 MeV -28

???

C.Z Yuan et al (Belle) arXiv:0707.2541 PRL 99, 182004

M=4259 8 +2 MeV

= 88 23 +6 MeV -6

-9

BaBar values:

Resonance?Thresh effect?…?

No 1-- cc slot for the Y(4260)

42604260

X.H. Mo et al, hep-ex/0603024

Is the Y(4260) a cc-gluon hybrid?

c c

• qq-gluon excitations predicted 30 yrs ago • lowest 1-- cc-gluon mass expected at ~4.3 GeV • relevant open charm threshold is D**D (~4.28 GeV) • (J/) larger than that for normal charmonium • (e+e-) smaller than that for ordinary charmonium

Horn & Mandula PRD 17, 898 (1977)

Banner et al, PRD 56, 7039 (1997); Mei & Luo, IJMPA 18, 15713 (2003)

Isgur, Koloski & Paton PRL 54, 869 (1985)

McNeile, Michael & Pennanen PRD 65, 094505 (2002)

Close & Page NP B443, 233 (1995)

Y(4260) s

eems t

o matc

h all

of these

!!!

DD** thresholds in & “Y(4260)”

4.28-mD

D** spectrum

M(J/) GeV

No obviousdistortions

D1D

D2D

BaBar’s ’ peak at 4325MeV

Nbkg = 3.1 1.0

Nevt = 68 (<5.7 GeV/c2)

2-prob < 5.7 GeV/c2

Y(4260) 6.5 10-3

(4415) 1.2 10-13

Y(4320) 29%

e+e-ISR ’

M=4324 24 MeV

= 172 33 MeV

above all D**D thresholds

S.W.Ye QWG-2006 June 2006

Not Compatible with the Y(4260)

D1D

D2D

298 fb-1 (BaBar) hep-ex/0610057

BaBar PRL 98 252001 (2007)

4325 MeV ’ peak in Belle (new)

M=4324 24 MeV

= 172 33 MeV

548 fb-1

X.L. Wang et al (Belle) arXiv:0707.3699PRL 99, 142002 (2007)

Two peaks!

M=4664 11 ±5 MeV

= 48 15 ±3 MeV

M=4361 9 ±9 MeV

= 74 15 ±10 MeV

BaBar values

(both relatively narrow)(& both above D**D thresh)

(& neither consistent with 4260)

4260

Recent Newsele

ctric

ally

charg

ed!!

M(±’) from BK ±’

M2(K) GeV2

M2(’)

GeV

2

S.-K. Choi et al (Belle) arXiv:0708.1790PRL 100 this Friday!

K*KK2*K Veto Veto

M(’) GeV

6.5

M = 4433 ±4 ±1 MeV

tot = 45 +17 +30 MeV

Nsig =124 ± 31evts-13 -11

Could this be a reflectionfrom the K channel?

Cos vs M2(’)

16 GeV2

22 GeV2

M2(

’)

+1.0

-1.0

cos

M (’) & cosare tightly correlated;a peak in cos peak in M(’)

(4.43)2GeV2 0.25

’

K

Can interference between K partial waves produce a peak?

Only S-, P- and D-waves seen in data

inte

rfere

Add incoherently

Can we make a peak at cos≈0.25

with only S-, P- & D-waves?

Not without introducing other, even more dramatic

features at other cos (&,, other M’) values.

Comments on the Z+(4430)

Not a reflection from the K system~

No significant signal in B KJ/

It has non-zero charge not cc or hybrid

Mass, width & decay pattern similar to Y(4360) & Y(4660)

comments• There seems to be a new hadron spectroscopy in the M=3.5~5

GeV region– Maybe more than one– Bodes well for BESIII, Super-B factories & PANDA

• Some states are narrow even though they are far above decay thresholds

– e.g. Y(4660)’ & Z+(4430)’ have large Q but ≈50 MeV

• characterized by large partial widths (Bfs) to hadrons+J/(or ’)

– Br(X(3872)J/) > 4.3% (Isospin=1)– (Y(3940)J/) > 7 MeV – (Y(4260)J/) > 1.6 MeV

• States that decay to ’ not seen decaying to J/ (and vice-versa) – Bf(Y(4660)’) >> Bf(y(4660)J/) same for Y(4360) & Z(4430’– Y(4260) not seen in Y(4260)’

• The new 1-- states are not apparent in the e+e-D(*)D(*) cross sections

• There are no evident changes at the D**D mass threshold

(mine)

New 1-- states J/

J/

’

C.-Z. Yuan et al (Belle) PRD 77, 011105® (2008)

some of the states are near thresholds,but this is not a universal feature

DSDS thresholdsDD thresholds

D*D*

DD*

DD

tot

Y(4

660)

Y(4

360)

Y(4

260)

Y(4

008) The 1-- states

do not match wellto peaks in hadr.

cross-sections

Pakhlova (Belle) PRL 98, 092001 (2007)

Are there XYZ counterparts

for the ss- & bb- systems?

Belle:((5S)(nS))

2S

3S4S

(4S) (1S) +

(4S)(1S)477 fb-1 from Belle

44±

8 e

vts

“(5S)”(1S)23.6 fb-1 from Belle

(1/20 times the data &

~1/10th the crosssection)

325±

20

evts

!

8 times as many events!

Belle 0710.2577

K.F. Chen et al (Belle) PRL 100, 112001 (2008)

(2 weeks ago)

is Huge!!!

Partial Widths

N.B. Resonance cross section 0.302 ± 0.015 nb at 10.87 GeV PRD 98, 052001 (2007) [Belle]

Cf (2S) (1S) ~ 6 keV (3S) 0.9 keV (4S) 1.8 keV

Assume “(5S)” = (5S)PDG value taken for (nS) properties

>100 times bigger!!

It looks like there is a bbversion of the Y(4260)

lurking around the (5S)

If there are bb versions of the XYZ’s, why not ss versions as well?

W.-S. Hou PRD 74, 017504 (2007)

1-- Ys states around 2 GeV?Y(2175)f0(980)

from BaBar (confirmed by BESII)

e+e- f0(980)@ Ecm ~10.6 GeV

confirmed by BESII

M(f0(980) GeV

M.Ablikim et al (BES)PRL 100, 102003 (2008)

3 weeks ago

Luciano Maiani @ had-2007

Now it looks like there may also be XYZ-like spectroscopies for the s- & b-quark sectors

Lots of pieces

Y(4360)

Y(4

660)

Y(4260)

Y(4

050)

X(3872)

X(3940

)

X(416

0

)

Z(4430) Y(3940)

Are the

y al

l fro

m the

sam

e pu

zzle

?

謝謝

Inclusive BKx from BaBar

?

Fully reconstructed B- tags

M2(’) / cos plot1.0< M(K)<1.4 GeV

Our attempts to fit theM=4.43 GeV (cos=0.25)

peak with any combination ofS-, P- & D-waves

M(DD): Broad threshold enhancement

arXiv:0708.3812

Relativistic BW

D sidebands

D-reconstructed D-tag

3.8

Bg subtracted

Resonance?Thresh effect?… ?

BaBar looked for a charged partner of the X(3872) and excluded isospin 1: BF(B0 X- K+ ) BF(X J/ψ - 0 ) < 5.4 x 10-6

BF(B- X- K0 ) BF(X J/ψ - 0 ) < 2.2 x 10-5

c.f BF(B0 X0 K+ ) BF(X 0 J/ψ -- + ) =(1.28 0.41 ) x 10-5

M() near 4008 & 4260 MeV

3.8 < M(J/) <4.2 GeV 4.2 < M(J/) <4.4 GeV

Y(4660) f0(980) ’?

4.0 < M(’) <4.5 GeV 4.5 < M(’) <4.9 GeV

f0(980)?

K+K- J/ from Belle (very new)

C.Z.Yuan et al (Belle) arXiv:0709.2565

(4415)?

M=4875 132 MeV

= 630 126 MeV M=4430 +38 MeV

= 254 +55 MeV

4260

-43

-46

M(K+K-)