Homeless mesons

X3872

Y394

0Y4260

Stephen L. OlsenUniversity of Hawai’i

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

Quarks restore economy(& rescue future Fermis from Botany?)

(& 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

-: u+2/3

u-2/3

d+1/3 s+1/3

u+2/3

d-1/3 s-1/3

Gell-Mann3 quarks

Zweig

Baryons: qqq

Fabulously successful, but…

• 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

Das ist verboten!!

The strong interaction “charge” of each quark comes

in 3 different varietiesY. Nambu

O. Greenberg

s-1/3

s-1/3

s-1/3

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

-

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: eisotriplet 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

“running” s

Why are these people smiling?

Probe QCD from other directions

Proposed non-qq or non-qqq hadron spectroscopies:

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

Pentaquarks“Seen” in many experiments

BaBar

CDF

but not seen in just as many others

High interest:1st pentaquark paperhas ~500 citations

Belle

BES

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

5.2

CLAS-D (2003)

nosignal

CLAS (2005)

???

Pentaquark Scoreboard

Positive signals Negative results

Also: Belle Compass L3 CLAS

Yes: 17 No: 18

Plenary speaker at LP05

“The pentaquark is not in good health, but it is still

alive.” -

Volker D Burkert Jefferson Lab

This talk: non-standard mesons with “hidden charm”

• standard cc mesons are:– best understood theoretically– narrow & non overlapping

• c + c systems are commonly produced in B meson decays.

b

cc

s

Vcb

cosC

CKM favored

W-

c c

u cuc (i.e containing c & c)

Thanks to KEKB we have lots of B mesons

(>1M BB pairs/day)>1fb -1/day

Design: 10 34

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

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

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

The X(3872)

????

Study J/ produced in BK J/decays

The X(3872)

BK 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?

no obvious cc assignment

3872

c”M too low and too small

angular dist’n rules out 1

J/ way too small

c too small;M() wrong

c& DD) too small

c should dominate

SLO hep-ex/0407033

hc’

c1’

2

2

3

go back to square 1

DetermineJPC

quantum numbersof the X(3872)

with minimal assumptions

JPC possibilities (for J ≤ 2)

0--

exotic

violates parity

0-+

(c”)

0++

DD allowed

(c0’)

0+-

exotic

DD allowed

1- -

DD allowed

((3S))

1-+

exotic

DD allowed

1++

(c1’)

1+-

(hc’)

2- -

(2)

2- +

(c2)

2++

DD allowed

c2’)

2+-

exotic

DD allowed

JPC possibilities0-- ruled out; JP=0+,1- & 2+ unlikely

0--

exotic

violates parity 0-+

(c”)

0++

DD allowed

(c0’)

0+-

exotic

DD allowed

1- -

DD allowed

((3S))

1-+

exotic

DD allowed

1++

(c1’)

1+-

(hc’)

2- -

(2)

2- +

(c2)

2++

DD allowed

c2’)

2+-

exotic

DD allowed

Strong evidence for C=+1

13.6 ± 4.4 X(3872)J/evts (>4significance)

X(3872)J/

virtual (782)?

X(3872)J/

Bf(XJ/)

Bf(XJ/)=0.14 ± 0.05

Br(X3J/)Br(X2J/) = 1.0 ± 0.5

M()

M()

X(3872)J/

Fits to (760)

JPC possibilities (C=-1 ruled out)

0--

exotic

Violates parity 0-+

(c”)

0++

DD allowed

(c0’)

0+-

exotic

DD allowed

1- -

DD allowed

((3S)) 1-+

exotic

DD allowed

1++

(c1’)

1+-

(hc’)

2- -

(2) 2- +

(c2)

2++

DD allowed

c2’)

2+-

exotic

DD allowed

Angular Correlations

K

J/ee

J=0J=0X3872

Jz=0

z

Rosner (PRD 70 094023)

Bugg (PRD 71 016006)

Suzuki, Pakvasa (PLB 579 67)

l

|cosl|

2/dof = 34/9

|cos|

|cos|

2/dof=34/9

0++ 0-+

rule out 0++ & 0 -+

J kxJ

JPC possibilities (0-+ & 0++ ruled out)

0--

exotic

violates parity

0-+

(c”)

0++

DD allowed

(c0’)

0+-

exotic

DD allowed

1- -

DD allowed

((3S)) 1-+

exotic

DD allowed

1++

(c1’)

1+-

(hc’)

2- -

(2) 2- +

(c2)

2++

DD allowed

c2’)

2+-

exotic

DD allowed

Fits to the M()

DistributionXJ/ in P-wave has aq*3 centrifugal barrierX

J/

q*

q*

M() can distinguish -J/ S- & P-waves

S-wave: 2/dof = 43/39 P-wave: 2/dof = 71/39

q*roll-off

q*3

roll-off

(CL=0.1%)(CL= 28%)

Shape of M() distribution nearthe kinematic limit favors S-wave

Possible JPC values (J-+ ruled out)

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

X(3872) D0D00 ?

11.3±3.6 sig.evts (>4)

Bf(BKX)Bf(XDD)=2.2±0.7±0.4x10-4

D*0D00?

M(D0D00)

• 1++ : DD* in an S-wave q*

• 2++ : DD in a D-wave q*5

Strong threshold suppression

Possible JPC values (2++ ruled out)

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++

can it be a 1++ cc state?

1++c1’(the only possibility)

3872

Bf(XJ/)>4%is very large for an isospin-violating

channel(Isospin

violating)

M=3872 MeV is too low, especially now that we know that M(c2’)=3931 4

MeV

Expectations for ’c1

(’c1 J/) 11 keV Barnes Godfrey PRD 69

054008

(’c1 J/) = ? (’ J/) 0.3 keV (“educated” guess?)

Bf(XJ/)

Bf(XJ/) 30 ~ 40

Bf(XJ/)

Bf(XJ/)=0.14 ± 0.05

Expect:

Meas:

>200x discrepancy

c1’ component of X(3872) is few% (at most?)

can our “education” really be this

bad?

Intriguing fact

MX3872 =3872 ± 0.6 ± 0.5 MeV

mD0 + m D0* = 3871.2 ± 1.0 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)

Deuson? deuteron-like DD* bound state?

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

diquark-antidiquark?

Maiani et al predict: M = M(Xu) – M(Xd) = 8 3 MeV

BaBar (hep-ex/0507090) reports: M = 2.71.3 0.2 MeV

u cuc

d cdc

Maiani etal predicta doublet of statesPRD 71,014028 (2005)

Xu= Xd=

B+K+Xu B0K0Xd

BaBar BaBar

Are there others?Is the X(3872) a one-of-a-kind curiousity?

or the 1st entry in a new spectroscopy?

Look at other B decays hadrons+J/

BK J/

BK J/

BK J/

BK J/ in Belle

“Y(3940)”M≈3940 ± 11 MeV≈ 92 ± 24 MeV

Mbc Mbc Mbc

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

M(J/) MeV

Y(3940): What is it?

• Charmonium?– Conventional wisdom: (SU(3)-

violating) J/decayshould not be a discovery mode for a cc state with mass above DD & DD* threshold!

eg.Brambilla et al (QWG) hep-ph/0412158

• cc-gluon hybrid?– predicted by QCD,– decays to DD and DD* are suppressed (“open-charm” thresh = mD + m D** = 4.3 GeV)

– large hadron+J/ widths can occur– masses expected to be 4.3 ~ 4.4 GeV

(higher than what we see)

Horn & Mandula PRD 17 898 others

/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

BaBar’s Y(4260)

(e

+e

- h

ad

ron

s)

summary• X(3872):

– Existence well established– JPC = 1++

– Br(X J/) too high for charmonium– Br(XD0D00) too high for molecule

– Br(B0 KSX3872) also too high for molecule(?)

– M too small for diquarks?

– Mass too low for hybrid

by a factor o

f

more than 200!

still under study

The more we learn more about it the more puzzling it

becomes.

(M(Xu) (from B+K+Xu) - M(Xd) (from B0KSXd)

other odd-balls

• Y(3940) Belle– ( Y3940 J/too high for charmonium

– Mass too low for a hybrid

• Y(4260) BaBar– (y4260J/also way too high

– 1--, but not seen in e+e- hadrons

by factors of ~103

3872

Charmonium chalet

Isospin violators not welcome

Fussy!

Y3940

Y4260

Looking for

a home:

3872

rats!Molecule Manors

DD

Y3940Y4260

3872

Hydrid heaven

M<4.2 GeVneed not apply

Fat Cats!

Y3940Y4260

3872

Diquark dives

*#!?&%$!

Doublets onlyno singlets!

Y3940Y4260

Conclusion

• either:– The “standard model” for

charmonium mesons needs major revision

• or:– There is a new hadron spectroscopy

in the 3.5~4.5 GeV mass region

Opportunities for CLEO-c & BES-III ???

Back-up slides

Xu – Xd Mass difference?:

MXu – M’ = 185.7 0.6 MeV

MXd – M’ = 184.0 1.3 MeV

M(Xu) – M(Xd) = 0.8 1.4 MeV

Belle:

Preliminary

Another one?

• e+e- J/ + X

>4)peak at M=394011 MeVN=14833 evtsWidth consistent w/ resolution

(= 32 MeV)

c

cc0

c‘

‘

What is it? c0 ? c ?? ‘ “

Look at e+e-J/ D(D(*))

•Reconstruct a J/ & a D•use D0K-+ & D+K-++

•Determine recoil mass

Look at M(DD(*))

DD*

DD

3940 MeV

9.9 ± 3.3 evts(4.5 )

4.1 ± 2.2 evts(2.1 )

c0 DD*‘

c DD“

Other hadronium states?

M=1859 MeV/c2

< 30 MeV/c2 (90% CL)

J/pp in the BES expt

M(pp)-2mp (GeV)

0 0.1 0.2 0.3

acceptance

2/dof=56/56

fitted peak location

+3 +510 25

J.Z.Bai PRL 91,022001(2003)