Searches for exotic mesons

Stephen L. Olsen University of Hawai’i

DOE site visit Aug 22, 2005

c c

ud

uud

u

u cuc•Multi-quark molecules

•qq-gluon hybrids

•baryonium

test of QCD: “running” s

Probe QCD from other directions

non-qq or non-qqq hadron spectroscopies:

Reawakened by the claims for Pentaquarks

e.g. an S=+1 baryon

ud

usd

Pentaquarks?“Seen” in many experiments

BaBar

High interest:1st pentaquark paperhas >500 citations

BelleBES

but not seen in just as many others

CDF

Compass

Jlab p

Pentaquark Scoreboard

Positive signals Negative results

Also: Belle Compass L3 Jlab(CLAS) (pK+Ksn)

Yes: 17 No: 18

This talk

• Searches for non-standard mesons with hidden charm at Belle

• Search for baryonium mesons at BES

c cu cuc

ud

uud

u

searches for non-standard mesons with “hidden charm” at Belle

• 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, Belle has lots of B mesons

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

Design: 10 34

X(3872)J/

BK J/

M(J) –M(J/)

’J/

X(3872)J/

S.-K.Choi, S.L.Olsen et al (Belle)PRL 91 262001 (2003)

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”

hc’

c1’

2

c2

3

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

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/

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

2/dof=18/9

0++ 0-+

rule out 0++ & 0 -+

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

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++1++

can it be a 1++ cc state?

1++c1’

3872

Mass is too low

Bf(XJ/)>4%

is too large(Isospin

forbidden)

c1’ component of X(3872) is ≤ few%

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?

Equal mixture of I=1 & I =0

Swanson PLB 598, 197 (2004)

Tornqvist PLB 590, 209 (2004)

Swanson PLB 588, 189 (2004)

X(3872) conclusion

•JPC = 1++

•cc content is small

•matches most expectations for a D0D*0 bound state

C C

u cuca non-qq meson

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: J/ should not be

a discovery mode for a cc state with mass above DD & DD* threshold!

• Some kind of -J/ threshold interaction?– the J/is not surrounded by brown

muck; can it act like an ordinary hadron?

J/

Brambilla et al (QWG) hep-ph/0412158

Y(3940): What is it (cont’d)?

• another tetraquark?– M ≈ 2mDs

– not seen in YJ/• ( contains ss)

– width too large??– no exchange for DSDS

s csc

??PRL 93, 041801

M( J/)

Y(3940): What is it (cont’d) ?

• 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 are predicted– masses expected to be 4.3 ~ 4.4 GeV

(higher than what we see)

c c

Horn & Mandula PRD 17 898 (1974) + (many) others

BaBar’s Y(4260)

)or ( /ISR eeJ/ψJee

211 fb-1 data collected at √(s) = 10.58 GeV

(2S) Y(4260)

11802110 (2S) evts12523 Y(4260) evts

J/ sideband

Well above DD & DD* threshold but found in an OZI-suppressed mode??

M=4259 8 MeV

= 88 23 MeV

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

cc summary• X(3872):

– JPC established as 1++

– cc component is small (≤ few %)– all properties consistent with a D0D*0

bound stateu cuc

a non-standard meson

• Y(3940) Belle, Y(4260) BaBar

c c

?????

- Lots to do: determine JPC ; find other modes (DD*, DsDs, …?)

Hardronic charmonium transitions

(’J/) 70 keV

(”J/) 50 keV

(’J/) 5 keVSUF(3) violating

HW (for theorists):How can (Y3940)J/)and (Y(4260)J/)be ~1000x larger?

Baryonium at BES???

ud

uud

u

J/ pp (at BES)

M(pp)

M(pp)-2mp (GeV)

0 0.1 0.2 0.3

M=1859 MeV/c2

< 30 MeV/c2 (90% CL)

+3 +510 25

3-body phase space

acceptance weighted BW

Phys. Rev. Lett. 91, 022001 (2003)   

Baryonium potential & Wave fcn

X ’ should be a strong channel

-V0(r)

Potentialbarrier

G.J. Dung & M.L. Yan hep-ph/0502127

“Rectangularized”Skyrmion-type

potentialI = 0, Jpc=0-+

pp annihilationM ~ 1860 MeV ~ 16 MeV large

uncertainties

M(’) from J/ ’

54264obsN

410)4.04.02.2()()( XBXJB

7.7The +- mass spectrum for decaying into +- and

BESII Preliminary

59.18.0 10)4.00.7()()(:..

ppXBXJBfc

M = 183463 MeV = 68 20 8 MeV

Re-fit to J/p p including FSI

Include FSI curve from A.Sirbirtsev et al. ( Phys.Rev.D71:054010, 2005 ) in the fit (I=0)

M = 1830.6 6.7 MeV

= < 153 MeV @90%C.L.

ppp mM 2In good agreement

with X(1835)

_

Appendix

• Other new hidden charm particles from Belle (near 3940!)– X(3940)– Z(3931)

Other new particles from Belle

e+e-J/ + X

X(3940)DD* seen(DD & J/ not seen)

Z(3931) DD at Belle

41 11 evts (5.5)

M=3931 4 2 MeV

208 3 MeV

sin4 (J=2)

X(3940) Y(3940) (maybe the c’’)

?

Z(3931) = c1’ (almost for sure)

Hawaii particles

• c’

•X(1860)(pp)

•X(3872)

•Y(3940)

Back-up slides

• c2,c0<<c1•X(3872) production much lower than for other Charmonium states:•can set lower limit on B.F.

Can measure absolute B.F.’s of B-K-X0

e+e-B+B-

K-X0

Lower limit on BF(XJ/) > 4.3% @ 90% C.L

244 fb-1

Very clear J/ and c signals N J/=258+- 42N c =266 +-42

c2 c1 c0

J/

Jon ColemanMoriond-QCDMarch 2005

Kinematic variables

CM energy difference:

Beam-constrained mass:

2/

2 )()2( JKCMbc ppEm

BK J

BKJ2// cmJK EEEE

B

Bϒ(4S)

Ecm/2

e e

Ecm/2

Mbc

E

1++

l

1++: sin2l sin2

K

1++ looks okay!

compute angles inX(3872) restframe

|cosl|

2/dof = 11/9

|cos|

2/dof = 5/9

M(J/) look-back plot

Fit cosl with 1++ MC

|cosl|

2/dof=11.9/9