Searching for new forms

of hadronic matter Stephen L. OlsenUniversity of Hawai’i

& 高能物理所 北京

Wuhan

武汉10/15/07

History:(sub-atomic

particles)

1932: proton & neutron

..all we need???

1937: muon

“Who ordered that?”

1947: pion

predicted in 1935

1950’s: ,,,,,…

“Had I foreseen that, I would have

gone into botany” – Fermi

chadwick

Fermi

TingPeters Jones

Rabi

Yukawa

Joliet-Curie

Hadron “zoo”mesons baryons

No “econom

y”

Constituent Quark Model: 1964

(& 3 antiquarks)

Mesons: q q

p: u+2/3

p: u-2/3

+: d-1/3

u+2/3

d+1/3

u-2/3

u-2/3

d+1//3

u+2/3

-: d-1/3

u-2/3

d+1/3 s+1/3

u+2/3

d-1/3 s-1/3

Gell-Mann 3 quarks

Zweig

Baryons: qqq

Constituent Quark Model: 2007

(& 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

Fabulously successful at bringing order to the hadron

“zoo”

mesons baryonsqq qq

q

“econom

y”is re

covere

d

Fabulously successful, but…

• Why are isolated quarks are not seen?

• why only qqq and qq combinations?

• What about spin-statistics?

s-1/3

s-1/3

s-1/3

three s-quarksin the same

quantum state

禁止

The “charge” for the strong force

is a 3-dim spinor

Y. NambuO. Greenberg

s-1/3

s-1/3

s-1/3

the 3 s-1/3 quarks in the- have different colorcharges & evade Pauli

-

Each quark can have 3 different “color” charges

QCD: Gauge theory for color charges

generalization of QED

+ i e A + i i Gi

QED gauge Xform QCD gauge Xform

eight 3x3 SU(3) matrices

8 vectorfields

(gluons)

1 vectorfield

(photon)

scalar charge: e triplet charge:

er

eb

eg

QED QCD

Yang MillsNambu

Fritzsch & GellMann

Attractive configurations

ijk eiejek

i ≠ j ≠ k

ij ei ej

same as the rules for combining colors to get white:

add 3 primary colors or add color+complementary color

antiquarks: anticolor charges

Hence the name: Quantum Chromodynamics

quarks: eiejek color charges

ejei ek

Difference between QED & QCD

QED: photons have no charge

QCD: gluons carry color chargesgluons interact with each other

Coupling strengths

distance

Test QCD with 3-jet events(& deep inelastic scattering)

rate for 3-jet events should decrease with Ecm

gluons

s

Energy

dist

“running” s

Winners of the2004 Nobel Prize

Running as tests QCD at short distances only

distance

The long-distance regime,where the matter we are made of exists, remains untested.

Are there other color-singlet arrangements?

Pentaquarks:e.g. an S=+1 baryon

(only anti-s quark has S=+1)

Glueballs:gluon-gluon color singlet states

Multi-quark mesons:

qq-gluon hybrid mesons

u cuc

c c

ud

usd

Non-quark model states expected in QCD

Spring8 electron Ring in Japan

A pentaquark?

T.Nakano et al (LEPS) PRL 91 012002 (2003) 742 citations!!

+(1530)?

M(K+n)

s+1//3

u+2/3 u+2/3

d-1/3

d-1/3

S=+1 baryon: impossible

with only qqq

+ n K- K+ n

Experimental situation is messy(some contradictory experiments)

SAPHIR (2004)4.8

M(nK+)(GeV)

Cou

nts

/4 M

eV

nKKγp s

CLAS (2005)

Same reaction

Some groups contradict themselves

5.2CLAS-D (2003)

nosignal

CLAS-D (2005)

???

d+K-K+n

Pentaquark Scoreboard

Positive signals Negative results

Also: Belle Compass L3 CLAS

Yes: 17 No: 18

Status in 2006

“ The conclusion that pentaquarks in general, and the in particular, do not

exist, appears compelling.” - George Trilling LBL

This is a risky business

You never know if nature is smiling at you

or something else

Another approach: look for non-qq mesons

c c

u cuc

4 (& 6) quark states

“ hybrid” qq-gluon states

u u

uud

d

theory:mc2>4.2 GeV

The Beijing Electron Positron Collider (BEPC)

e+

e-

高能物理研究所

Beijing Spectrometer (BES)

e+e- annihilation cross section

sscc

bb

Ecm(GeV)

q

q

BES Energy Range

J/ pp

C-2//3

c+2/3

p

p

u

uu

ud

d

J/ pp

This is the cpp

the J/’s wellknown S=0

partner

What is this???

M(pp) GeV

BESII

J.Z. Bai et al. (BESII)PRL 91 022001 (2003)

Fit the M(pp) distribution

Best fit to this peakis a resonance withpeak mass below thepp mass threshold

M=1830.6 ± 6.7 MeV/c2

< 153 MeV/c2 (90% CL)

matches to no known state.

A pp bound state (baryonium)?

p n p p

deuteron:

loosely bound 3-q 3-

q color singlets with Md = 2mp-

baryonium:

loosely bound

3-q 3-q color singlets with Mb = 2mp-

?

attractive nuclear force attractive force?

There is lots & lots of literature about this possibility

An old idea

Fermi & Yang in 1949 (7 years before p discovery):

If NN potential is attractive, they could bind to form -like states.

Expectation for pp bound state meson

mp +mp

Above threshold

Xpp ~100%

below-threshold p

and p annihilate to

mesons

I=0, JPC=0-+ init. state:pp ’ is common

Ding & Yan Phys.Rev.C72:015208,2005.

BES looked at J/ ’

M(’)

M=1833 MeV 70MeV

mp+mp

These values matchthose for the pp peak

(as predicted by Ding&Yan)

BESII

M. Ablikim et al. (BESII)PRL 95, 262001 (2005)

X(1835): a“6-quark” meson?

3 quarks+

3 antiquarks

•Need to confirm JPC of the ’ peak is 0-+

•Need to find it in other common 0-+ pp annihilation channels

job for BESIII

uu

u

ud

d

Move over to Japan

Tsukuba Mountain

KEK laboratory

KEKB Collider

International Collaboration Belle

e+e- annihilation cross section

sscc

bb

Ecm(GeV)

q

q

KEK B-factory

B meson decays

u-2/3

b-1/3 C-2/3

C+2/3

u-2/3

S-1/3

W -

K-

“Charmonium”

Primer on Charmonium

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

quantum chromodynamics

“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

All of these statesare well established

J/

’

c

c’c

’’

hc

Study BK-J/

u-2/3

b-1/3 C-2/3

C+2/3

u-2/3

S-1/3

W -

look here

J

K

The X(3872)

BK J/

M(J) – M(J/)

’J/

X(3872)J/

S.K. Choi et al PRL 91, 262001

Its existence is well established

seen in 4 experiments

X(3872)

CDF

X(3872)

D0

hep-ex/0406022

9.411.6

Is it a cc meson?

These states are alreadyidentified

3872 MeV

Could it beone of these?

The JPC quantum numbersof the X(3872) are 1++

From studying different decay processes& angular correlations among decay

products

can it be the 1++ cc state?

1++c1’(the onlycharmonium possibility)

3872

XJ/decayis a forbidden

decay

(Isospin violating)

M=3872 MeV is low,

Allowed E1transition

23P1 cc state

Intriguing fact

MX3872 =3871.2 ± 0.5 MeV

mD0 + m D0* = 3871.6 ± 0.4 MeV

lowest masscharmed meson

lowest mass spin=1charmed meson

D D*

2 loosely bound qq color singlets

with M = mD + mD* -

u

cu

c

one exchangeattractive for 1++

Tornqvist PLB 590, 209 (2004)Braaten et al, PRL 93, 162001

Deuson? deuteron-like DD* bound state?

Another old ideaDeRujula, Georgi,Glashow, PRL 38, 317 (1977)

X(3872)??

X(3872) summary

– Existence well established– JPC = 1++

– Br(X J/) too high for charmonium– Mass too low for hybrid

Four years after discovery, theoristsare still puzzling over what it may be

Next, CaliforniaStanford LinearAccelerator Ctr

BaBar Detector

Radiative return

sscc

bb

Ecm(GeV)

10.58 GeV

B-factoryenergies

3~5GeV

/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)PRL 95 142001 (2005)

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

Y(4260)

(e

+e

- h

ad

ron

s)

a 1-- cc slot for the Y(4260)?

42604260

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

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

no cc sl

ot for

it!no cc

slot f

or

it!

Theorist’s favorite interpretation

c c

“ hybrid” qq-gluon states

just about the right mass for theory

A ’ 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

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)

New results on the ’ peak from Belle

548 fb-1

X.L. Wang et al (Belle) arXiv:0707.3699

It is really two peaks!

M=4664 11 ±5 MeV

= 48 15 ±3 MeV

M=4361 9 ±9 MeV

= 74 15 ±10 MeV

(both relatively narrow)

(neither one consistent with 4260)

4260

Need 2 more 1-- cc slots for Y(4630) & Y(4660)

42604260

X.H. Mo et al, hep-ex/06030244660

4360

Excited hybrid states?

c c

Latest Newsele

ctric

ally

charg

ed!!

M(±’) from BK ±’

K. Abe et al (Belle) arXiv:0708.1790

M(’) GeV

6.5

M = 4433 ±4 ±1 MeV

tot = 45 +17 +30 MeV

Nsig =124 ± 31evts-13 -11

Can’t be a cc meson or a hybrid

4260

4660

4360

No charged cc hybrid states

gluons have zero charge

C+2/3 C-2/3

SummaryMesons with no qq assignment:

M(pp) GeV

X(1835)

M(J) – M(J/)

X(3872)J/

Y(4260)

548 fb-1

Y(4660)

Y(4360)

M(J)

M(’) GeV

Z±(4430)Y(3940)

M(J/) MeV

BESII

Concluding remarks

• A number of “mysterious” mesons that don’t fit into the simple quark model picture have been found

• If they are related to each other, these particles can’t be the hybrid states predicted by QCD

• Are these curiosities, each with its own story? … or are they 1st signs of a spectroscopy of new

forms of hadronic matter?

• Hopefully, time, & more experimentation, will tell

謝謝

Thank you

Back-up slides

Conclusion

• either:– The constituent quark model for

mesons needs major revision

• or:– There is a new, non-qq, hadron

spectroscopy, maybe more than one.

Difference between QED & QCD

QED: photons have no charge

QCD: gluons carry color chargesgluons interact with each other

Vacuum polarization QED vs QCD

2nf

11CA

in QCD: CA=3, & this dominates

The LEPS observation of +(1530)

n

K- n

K+

+ n K- K+ n

M(K+ n)

s+1//3

u+2/3 u+2/3

d-1/3

d-1/3

(1530)

Physical Review Letters, 91, 012002 (2003)

+ n K- + K- K+ n

S=+1

Charmonium state?(

e+e

- h

ad

ron

s)

No sign of it (e+e-hadrons)at Ecm =4.26 GeV

BES

4260

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

No pla

ce fo

r

it!No p

lace

for

it!

Actual fit

M=1830.6 ± 6.7 MeV/c2

< 153 MeV/c2 (90% CL)

J/pp in the BES expt

0 0.1 0.2 0.3

2/dof=56/56

fitted peak location

A pp bound state (baryonium)?

p n p p

deuteron:

loosely bound 3-q 3-

q color singlets with Md = 2mp-

baryonium:

loosely bound

3-q 3-q color singlets with Mb = 2mp-

?

attractive nuclear force attractive force?

There is lots & lots of literature about this possibility

E. Fermi, C.N. Yang, Phys. Rev. 76, 1739 (1949)

Y.Nambu, G. Jona-Lasinio Phys Rev 122, 345 (1961) …I.S. Shapiro, Phys. Rept. 35, 129 (1978)C.B. Dover, M. Goldhaber, PRD 15, 1997 (1977)…A. Datta, P.J. O’Donnell, PLB 567, 273 (2003)]M.L. Yan et al., hep-ph/0405087B. Loiseau et al., hep-ph/0411218

…

These are very famous papers

!!!

The X(3872)

????

Study J/ produced in BK J/decays

hadronic molecules

a new spectroscopy?

may be more particles to find

summary• X(1835):

– Existence well established– JPC = 0-+

– Br(Xpp) too high for qq meson– X’ is expected for sub-thresh pp

state

l

|cosl|

2/dof = 34/9

|cos|

|cos|

2/dof=34/9

0++ 0-+

rule out 0++ & 0 -+

J kxJ

Ruled out by Belle

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

&Belle

PRL 96 102002

M( looks like a

X(3872)””J/ seen

CDF Belle

Belle

hep-ex/0505037

Angular analysis from CDF

CDF Collab. PRL 98, 132002 (2007)

1++

or2-+

Use Angular Correlations to determine J & P

K

J/ee

J=0J=0X3872

Jz=0

z

Rosner (PRD 70 094023)

Bugg (PRD 71 016006)

Suzuki, Pakvasa (PLB 579 67)

Possible JPC values

0--

exotic

violates parity

0-+

(c”)

0++

DD allowed

(c0’)

0+-

exotic

DD allowed

1- -

DD allowed

((3S))

1-+

exotic

DD allowed1++

(c1’)

1+-

(hc’)

2- -

(2)

2- +

(c2)

2++

DD allowed

c2’)

2+-

exotic

DD allowed

1++

X(3872) = D0D*0 bound state?

• JPC = 1++ is favored

• M ≈ mD0 + mD0*

• Large isospin violation is natural (& was predicted):

|D0D*0> = 1/2(|10> - |00>)

• (XJ/) < (XJ/) was predicted

• (XD0D00) too large?

• Bf(B0K0X3872)/Bf(B+K+X3872) too large?

Equal mixture of I=1 & I =0

Swanson PLB 598, 197 (2004)

Tornqvist PLB 590, 209 (2004)

Swanson PLB 588, 189 (2004)

Braaten & Kusunoki PR D71, 074005 predict: <0.08BaBar measurement (hep-ex/0507090): 0.5 0.3

Y(3940) in BK J/

M≈3940 ± 11 MeV≈ 92 ± 24 MeV

Belle PRL94, 182002 (2005)

M(J/) MeVM2(K) GeV2

M2(

J

) G

eV2

If not charmonium, what?

c c “ hybrid” cc-gluon state?

But why does it decay to J/, and not to D and D*

mesons?

Y(4260) summary

– Existence well established– JPC = 1--

– (X J/) too high for charmonium– Br(XD(*)D(*)) too low for hybrid

Another mystery!!

J/ pp

C-2//3

c+2/3

u+2/3

u-2/3

d-1/3u+2/3

d+1/3

u-2/3

p

p