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The hidden charm of hadronsPowerPoint Presentation

The hidden charm of hadrons

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### Intriguing fact

The hidden charm of hadrons

Stephen L. Olsen University of Hawai’i

Representing Belle

Invited talk at the Tampa APS/DPF meeting, April 19, 2005

Probe QCD from other directions

non-qq or non-qqq hadron spectroscopies:

Pentaquarks:

e.g. an S=+1 baryon

Glueballs:

gluon-gluon color singlet states

Multi-quark mesons:

qq-gluon hybrid mesons

d

u

u

d

s

u

c

u

c

c

c

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

u

c

u

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

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

c

(i.e containing c & c)

c

c

c

c

Vcb

b

W-

cosqC

s

CKM favored

Its existence is well establishedseen in 4 experiments

CDF

9.4s

11.6s

X(3872)

D0

X(3872)

hep-ex/0406022

no obvious cc assignment

hc”

hc’

cc1’

y2

hc2

y3

M too low and G too small

angular dist’n rules out 1+-

3872

G(gJ/y) way too small

G(gcc1) too small;M(p+p-) wrong

pp hc should dominate

G( gcc2 & DD) too small

SLO hep-ex/0407033

JPC possibilities (for J ≤ 2)

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

Areas of investigation

- Search for radiative decays
- Angular correlations in XppJ/y decays
- Fits to the M(pp) distribution
- Search for X(3872)D0D0p0

Search for X(3872)g J/y

Kinematic variables

BK gJ/y

Ecm/2

e+

e-

B B

ϒ(4S)

Ecm/2

DE

CM energy difference:

BK gJ/y

Beam-constrained mass:

Mbc

Select BKg J/y

BKcc1; cc1g J/y

X(3872)?

M(gJ/y)

Mbc

Mbc

13.6 ± 4.4 X(3872)gJ/y

evts (>4s significance)

Bf(XgJ/y)

Bf(XppJ/y)

=0.14 ± 0.05

Evidence for X(3872)p+p-p0 J/y(reported last summer hep-ex/0408116)

A virtual w(782)?

12.4 ± 4.2 evts

B-meson yields vs M(p+p-p0)

Br(X3pJ/y)

Br(X2pJ/y)

Large (near max)

Isospin violation!!

= 1.0 ± 0.5

C=+1 is established

- Xg J/y only allowed for C=+1
- same for X”w”J/y (reported earlier)
- M(pp) for Xp+p-J/y looks like a r

CDF

JPC possibilities (C=-1 ruled out)

Angular Correlations

r

Jz=0

J=0

X3872

J=0

K

z

Rosner (PRD 70 094023)

Bugg (PRD 71 016006)

Suzuki, Pakvasa (PLB 579 67)

J/y

Use 253 fb-1 ~275M BB prsexploit the excellent S/N

X(3872)p+p-J/y

y’p+p-J/y

Signal

(47 ev)

Sidebands

(114/10 = 11.4 ev)

0++

In the limit where

X(3872), pp, & J/y

rest frames coincide:

dG/dcosqlp sin2qlp

qlp

c2/dof = 34/9

|cosqlp|

rule out 0++

1++

compute angles in

X(3872) restframe

1++: sin2ql sin2c

c2/dof = 11/9

ql

K

|cosql|

c2/dof = 5/9

c

|cosc|

1++ looks okay!

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

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

P-wave: c2/dof = 71/39

S-wave: c2/dof = 43/39

(CL=0.1%)

(CL= 28%)

q*

roll-off

q*3

roll-off

Shape of M(pp) distribution near

the kinematic limit favors S-wave

Possible JPC values (J-+ ruled out)

Search for X(3872)D0D0p0

Select BKD0D0p0 events

D*0D0p0?

M(D0D0p0)

11.3±3.6 sig.evts (5.6s)

Bf(BKX)Bf(XDDp)=2.2±0.7±0.4x10-4

Preliminary

|DE|

|DE|

X(3872)DDp rules out 2++

- 1++ : DD* in an S-wave q*
- 2++ : DDp in a D-wave q*5

Strong threshold suppression

can it be a 1++ cc state?

1++ cc1’

- Mass is ~100 MeV off
- cc1’ r J/y not allowed by isospin.
Expect:

Bf(cc1’ppJ/y)<0.1%

BaBar measurement:

Bf(XppJ/y)>4%

3872

-G(cc1’gJ/y) / G(cc1’ppJ/y)

Expect: ~ 40

cc1’ component of

X(3872) is ≤few %

- G(X3872gJ/y) / G(X3872ppJ/y)
- Measure: 0.14 ± 0.05

lowest mass

charmed meson

MX3872 =3872 ± 0.6 ± 0.5 MeV

mD0 + m D0* = 3871.2 ± 1.0 MeV

lowest mass spin=1

charmed meson

X(3872) is very near DD* threshold.

is it somehow related to that?

D0D*0 bound state (deuson)?

N. Tornqvist

hep-ph/0308277

deuteron:

deuson:

attractive nuclear force

attractive force??

c

c

p

n

D

p

D*

p

u

u

2 loosely bound qqq color singlets with Md = mp+mn- e

2 loosely bound

qq color singlets with

M= mD + mD* - d

X(3872) = D0D*0 bound state?

- JPC = 1++ is favored
- M ≈ mD0 + mD0*
- Maximal isospin violation is natural (& was predicted):
|I=1; Iz= 0> =1/2(|D+D*->+ |D0D*0>)

|I=0; Iz= 0> =1/2(|D+D*-> - |D0D*0>)

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

- G(XgJ/y) < G(XppJ/y) was predicted

Tornqvist PLB 590, 209 (2004)

Equal mixture of I=1 & I =0

Swanson PLB 588, 189 (2004)

Swanson PLB 598, 197 (2004)

X(3872) conclusion

- JPC = 1++
- cc content is small
- matches all(?) expectations for a D0D*0 bound state

C

C

u

c

u

c

a 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/y:

BK h J/y

BK p J/y

BK w J/y

BK wJ/y in Belle

“Y(3940)”

M≈3940 ± 11 MeV

G≈ 92 ± 24 MeV

Mbc

Mbc

Mbc

S.K. Choi et al hep-ex/0408126

to appear in PRL

Y(3940): What is it?

Brambilla et al (QWG) hep-ph/0412158

- Charmonium?
- Conventional wisdom: wJ/y should not be a discovery mode for a cc state with mass above DD & DD* threshold!

- Some kind of w-J/y threshold interaction?
- the J/y is not surrounded by brown muck; can it act like an ordinary hadron?

w

J/y

Y(3940): What is it (cont’d)?

- another tetraquark?
- M ≈ 2mDs
- not seen in YhJ/y
- (h contains ss)

- width too large??
- no p exchange for DSDS

c

s

s

c

??

PRL 93, 041801

M(h J/y)

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/y 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

Summary

- X(3872):
- JPC established as 1++
- cc component is small (≤ few %)
- all properties consistent with a D0D*0 bound state

u

c

a non-standard meson

u

c

- Y(3940):
- No obvious cc assignment
- tetraquark seems unlikely
- cc-gluon hybrid?

c

c

?????

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

Moriond-QCD

March 2005

e+e-B+B- K-X0244 fb-1

- Can measure absolute
B.F.’s of B-K-X0

J/y

Lower limit on BF(XJ/ypp) > 4.3%

@ 90% C.L

cc2

cc1

cc0

Very clear J/y and hc signals

N J/y=258+- 42

N hc =266 +-42

- cc2,cc0<<cc1
- X(3872) production much lower than for other Charmonium states:
- can set lower limit on B.F.

M(gJ/y) look-back plot

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