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Hadron spectroscopy at Belle. J olanta Brodzicka (Krakow) Hadron Workshop, Nagoya 6-7 December 2008. Belle at KEKB. KEKB: a symmetric e + e - collider e + : 3.5 GeV  e - : 8.0 GeV √s= 10.58 GeV =  (4S) mass e + e -  (4S)  B B Operating since 1999

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hadron spectroscopy at belle

Hadron spectroscopy at Belle

Jolanta Brodzicka (Krakow)

Hadron Workshop, Nagoya

6-7 December 2008

belle at kekb
Belle at KEKB
  • KEKB:asymmetric e+e- collider

e+: 3.5 GeV  e-: 8.0 GeV

√s=10.58 GeV = (4S) mass

e+e-  (4S)  BB

  • Operating since 1999
  • Peak luminosity: 1.711034cm-2s-1
  • Integrated luminosity: 860 fb-1

750 fb-1 @ (4S)

~ 780 * 106 BB

~ 960 * 106 cc

Beauty and Charm Factory

history of spectroscopy at belle
History of spectroscopy at Belle

X(3872)

Z(3930)

Ξc(3077)

Ξc(2980)

Z+(4430)

Y(3940)

D*0

D*2

DsJ(2700)

2002: ηc’→KsKπ

X(3872) →J/ψπ+π-

D*0(2308)→Dπ and D1’(2420)→D*π

properties of D*s0(2317) and Ds1(2460)

Y(3940)→J/ψω

Z(3930)=χc2’→DD

X(3940)→DD*

Ξc(2980) Ξc(3077)→ΛcKπ

Y family→ψ(1S,2S)π+π-

DsJ+(2700) →D0K+

X(4260)→DD*

Z+(4430)→ψ(2S)π+

Z+(4051) Z+(4281)→χc1π+

2008: Yb(?)→Yπ+π-

cc-like XYZ states : exotics? I will focuse on them

conventional vs exotic states
Conventional vs exotic states

q

q

q

q

q

  • Quark Model by Gell-Manna and Zweiga (1964):

(qq) mesons and (qqq) baryons

= conventional states

  • QCD based potential models → hadron masses, decays,...

Observed cc multiplets agree with the models’ predictions

  • States more complex than qq or qqq

=exotics also predicted by the models

  • cc spectrum „cleaner” than uu/dd/ss

→ cc-like exotics easier to identify

2M(D)

menu of c c like exotics
Menu of cc-like exotics

c

g

q

c

c

q

c

q

c

π

q

c

D D(*)

  • Hybrids: cc+ excited gluon(excited flux-tube)
    • Lattice QCD: lightest hybrids @ 4.2GeV
    • Exotic quantum numbers JPC= 0+-, 1-+, 2+-…
    • Γ(H→DD**)> Γ(H→DD(*) )
    • Large Γ(H→ψππ, ψω,… )
  • Tetraquarks: diquark-antidiquark [cq][cq]
    • Tightly bound diquarks (gluon exchange)
    • Decay:„coloured” quarks rearrange into „white” mesons

→ dissociation

  • Molecules: M(cq)M(cq)
    • Meson and antimeson loosely bound (pion exchange)
    • Decay: dissociation into constituent mesons
  • How to identify exotic cc hadron?
  • JPC forbidden for conventional cc
  • Final states with non-zero electric charge and/or strangness:
  • J/ψπ- =(cc)(ud) Ds+D- =(cs)(cd)
  • Too small/large rates in some decay modes
production of c c in b factory
Production of ccin B Factory

b c

u, dc

s

u, d

c

γ* c

c

c

e+ J/ψ

X

e-

BX=ηcχcψ…

W

K

e+ e+

e- e-

γ

γ

γISR

γ*

X

π

π

ψ

D

D

X

e+

e-

  • double cc production
  • e+e-→J/ψXcc
  • γγ collision
  • e+e-→γγ→Xcc→DD
  • B meson decays:

B→XccK(BF~10-3)

  • initial state radiation (ISR)

e+e-→γISRXcc→γISRψππ

Good experimental environment to search for new resonances

JPC(X)=0++, 0-+

J(X)=0, 2

C(X)=+1

JPC(X)=1--

observation of z 4430
Observation of Z+(4430)→ψ’π+

Mbc

ΔE

M=4433±4±2MeV

Γ=45 MeV

+18 +30

–13 -13

???

Z+(4430)

M2(ψ’π+)

N=121±30

(6.5σ)

K2*(1430)

K*(890)

M(ψ’π+)

M2(Kπ+)

PRL100, 142001 (2008)

  • Study of B→ψ’π+K using 657M BB
  • ψ’→e+e-, μ+μ-, J/ψπ+π-
  • after
  • K* veto

Too low statistic to

determine JP

  • First charged cc-like state!Must be exotic!
  • Proposed interpretations:
  • [cu][cd] tetraquark;neutral partner in ψ’π0 expected
  • D*D1(2420)molecule;should decay to D*D*π
no significant z 4430 in babar
No significant Z+(4430) in Babar

hep-ex/0811.0564

  • B→ψ’π+K studied using413/fb
  • Mass spectra corrected for efficiency
b k dalitz plot analysis
B→ψ’π+KDalitz plot analysis

A B C D E

A B

C D

E

M2(ψ’π+)

A+C+E

=K*veto

M2(K-π+ )

M2(ψ’π+)

M2(ψ’π+)

  • B→ψ’π+K amplitude: coherent sumof Breit-Wigner contributions
  • Maximum likelihood fit to Dalitz plot
  • Models: all known K*→Kπ+ resonances only

all known K*→Kπ+ resonances and Z→ψ’π+favored by data

Z+(4430) confirmed

Significance: 6.4σ

Fit CL: 36%

b 0 c1 k study more z s
B0→χc1π+K- study. More Z’s

ΔE

M(J/ψγ)

???

M2(χc1π+)

K2*(1430) K*(1680)

K*(892) K0*(1430) K3*(1780)

M2(K-π+ )

PRD 78, 072004 (2008)

  • Dalitz-plot analysis of B0→χc1π+K-

χc1 →J/ψγwith 657M BB

  • B0→χc1π+K- amplitude: coherent sum
  • of Breit-Wigner contributions
  • Maximum likelihood fit performed
  • Models tried:
  • known K*’s→Kπ only
  • K*’s + one Z→χc1π+
  • K*’s + two Z states : favored by data
z 1 2 c1 exotic states
Z+1,2→χc1π+ exotic states
  • Model with two Z’s significantly favored by data
  • Spin of Zstatesnot determined: spin 0 and 1givesimilarfit qualities

M(χc1π+)

for 1<M2(K-π+)<1.75GeV

–̶̶̶̶̶̶ –̶̶̶̶̶̶fit for null model

–̶̶̶̶̶̶ –̶̶̶̶̶̶fit for double Z model

–̶̶̶̶̶̶ –̶̶̶̶̶̶Z1 contribution

–̶̶̶̶̶̶ –̶̶̶̶̶̶Z2 contribution

Non-zero charge suggests multiquark

interpretation of Z1 and Z2

c c like example x 3872
cc-like example: X(3872)

152M BB

M(J/ψπ+π-)

M(π+π-)

117MBB

PRL91, 262001 (2003)

  • X(3872)→J/ψπ+π- observed in B+→X(3872)K+ by Belle
  • Confirmed by BaBar, CDF, D0
  • mX=3871.2±0.5MeVmX-(mD*0+mD0)=-0.6±0.6MeVΓ<2.3MeV
  • M(π+π-) suggests X(3872)→J/ψρ (S- or P-wave)
  • Other decay modes: J/ψγ,ψ(2S)γ, J/ψω,

DD*, no X→DD

  • JPC= 1++,2-+favored

(from angular analysis by CDF,

M(π+π-),decay modes)

what is x 3872
What is X(3872) ?

M(J/ψπ-π0)

  • cc? No obvious assignment
  • D0D*0 molecule?

Non-trivial line shape

Γ(X→DD*)>Γ(X→J/ψππ)

Production in B0 suppressed

in regard to B+

  • 4-quark?

Xu[uc][uc] Xd[dc][dc]

Different mass of X produced

in B0 and B+

Finding charged X is critical

(no evidence so far)

Braaten et al. hep-ph/0710.5482

PRD71, 031501 (2005)

Maiani, Polosa et al.

PRD 71, 014028 (2005)

x 3872 in b vs b 0 decays
X(3872)in B+vs B0 decays

B0→XK0

Ns=30±7

(6.5σ)

B+→XK+

Ns=125±14

(12σ)

First observation!

657MBB

M(J/ψπ+π-)

M(J/ψπ+π-)

hep-ex/0809.1224

  • Study of X(3872)→J/ψπ+π-inB+→XK+ and B0→XK0s
  • Similar properties of X(3872) from B+ and B0 decays
x 3872 d 0 d 0
X(3872)→D0D*0 (?)

N=33±7 (4.9σ)

PRD77, 011102(2008)

B KD0D*0

D*→Dγ

M(X)=3875.1+0.7-0.5 ±0.5MeV

Γ=3.0+1.9-1.4 ± 0.9 MeV

Preliminary

D*→D0π0

605 fb-1

Flatte vs BW similar result: 8.8σ

  • X(3872)→D*0D0in B+→D*0D0K
  • New Belle M(X) measurement ruled out
  • scenario oftwo states: X(3872)→J/ψππand X(3875)→D*D

hep-ex/0810.0358

M(X)=3872.6+0.5-0.4±0.4MeV

Γ=3.9+2.5-1.3+0.8-0.3 MeV

Maiani, Polosa et al.

hep-ph/0707.3354

Xu[uc][uc]→D0D0π0= X(3875)

Xd[dc][dc]→ J/Ψππ = X(3872)

x 3940 and x 4160 in e e j x c c
X(3940) and X(4160) in e+e-→J/ψXcc

c

γ* c

c

c

e+ J/ψ

X

e-

ee→J/ψDD*

X(3940) 6.0σ

ee→J/ψD*D*

X(4160) 5.5σ

M=4156 ± 15 MeV

=139 ± 21 MeV

+25

–20

M =3942 ± 6 MeV

=37 ± 12 MeV

+7

–6

M(D*D)

M(D*D*)

+111

– 61

+26

–15

PRL100, 202001 (2008)

  • x-sections much larger than QCD predicted

→ factory of 0++ and 0-+ charmonia

  • Search for X→DD* and D*D* ine+e-→J/ψD(*)D*
  • Possible assignments: ηc(3S) ηc(4S)

(but X masses ~100-150MeV above predictions for ηc’s)

CX=+1 so

X(4160)≠ψ(4160)

y family through isr
Y family through ISR

M=4259 ± 8 MeV

=88 ± 23 MeV

+2

–6

+6

–4

γISR

γ*

π

π

ψ

Y

e+

e-

PRL 95, 142001 (2005) for 232fb-1

PRL 98, 212001 (2007) for 298fb-1

  • ISR gives access to JPC=1-- states
  • Hard photon emission suppressed,
  • ‘compensated’ by high luminosity of B-factory

Y(4260)→J/ψππ

M=4324 ± 24 MeV

=172 ± 33 MeV

Y(4360)→ψ’ππ

PRD74, 091104 (2006)

PRL 96, 162003 (2006)

for [email protected]

1 y states via isr
1 - - Y→ψππ states via ISR

e+e-→p+p-J/y

  • Y(4008), Y(4260), Y(4360), Y(4660)
  • More 1– states than empty slots in cc spectrum

Unusual properties:

  • Large widths for ψππ transition: unlike for conventional cc
  • Above DD threshold

but don’t match the peaks

in D(*)D(*) x-sections

Other options:

  • DD1 or D*D0 molecules
  • cqcq tetraquarks
  • ccg hybrid:

DD1decay mode should dominate

  • Coupled-channel effects
  • Charm-meson threshold effects

Y(4260)

Y(4008)

e+e-→p+p-y’

Y(4360)

Y(4660)

exclusive x sections with isr
Exclusive x-sections with ISR

PRD77,011103(2008)

DD

?

DD*

(4160)

Y(4350)

PRL98, 092001 (2007)

Y(4008)

D*D*

Y(4260)

(4415)

(4040)

PRL100,062001(2008)

Y(4660)

DDπ

arXiv:0807.4458

Λc+Λc–

NEW

PRD 77, 011103 (2008) for 673fb-1

PRL 98, 092001 (2007) for 548fb-1

  • Difficult interpretation in terms of resonances (model dependent coupled-channel and threshold effects…)

PRL 100, 062001 (2008) for 673fb-1

c c like state of art
cc (-like) state of art

Y(3360), Y(3660)

ηc(4S)

  • We have observed a few new states
  • Most of them don’t match cc spectrum
b b analog of y 4260
bbanalog of Y(4260)?

PRL100, 112001(2008)

  • If bb follows the ccpattern: Yb→Y(nS)ππ with large partial width
  • Study of Y(mS)→Y(nS)π+π-with dataat Y(5S)~10.87GeV(21.7/fb)
  • Energy scan around Y(5S) (7.9/fb)
  • Large Γ(Y(5S)→Y(nS)ππ)! For other bb states: Γ~O(keV)
  • Is it Yb? Mixture of Y(5S) and Yb?

Observed shape disagree

with Y(5S) hypothesis (fit).

Yb at 10.89GeV?

summary
Summary
  • New charmonium spectroscopy @4GeV
  • Candidates for exotic hadrons observed:

Z+(4430)→ψ’π+Z+(4050), Z+(4248)→χc1π+

  • Many other states await understanding

X(3872) Y(3940) Y-family…

  • Yb? New spectroscopy also in b quark sectors?
  • Theory input needed (models to verify, threshold effects, coupled channel effects)
x 3872 d 0 d 01
X(3872)→D0D*0 (?)

N=24±6 (6.4σ)

N=33±7 (4.9σ)

PRD77, 011102(2008)

M(X)=3875.1+0.7-0.5 ±0.5MeV

Γ=3.0+1.9-1.4 ± 0.9 MeV

  • Belle: B+→D0D0π0K(447MBB) BaBar: B+→D*0D0K (383MBB)
  • Mass ~4σ above M(X) for X→J/ψππ
  • Is this X(3872) or are theretwo states X(3872) and X(3875)?
  • More precise measurement of mass/width/line shape needed

PRL97, 162002(2006)

M(X)=3875.4± 0.7+0.4-1.7 ±0.9MeV

Xu[uc][uc]→D0D0π0 = X(3875)

Xd[dc][dc]→ J/Ψπ+π- = X(3872)

Maiani, Polosa et al.

hep-ph/0707.3354

y 3940 j
Y(3940)→J/ψω

K*’s

Y(3940)

M(ωJ/ψ)

M(ωJ/ψ)

M2(ωJ/ψ)

M2(ωK)

Belle PRL 94, 182002 (2005)

Babar hep-ex/0711.2047 submitted to PRL

  • Study of B→ KJ/ψωω→π+π-π0
  • Mbc, ΔE and M(π+π-π0) selection

mass/width discrepancy

needs further study

  • Y(3940) above DD threshold but has large cc transition
  • Candidate for cc-gluon hybrid?(but hybrids predicted >4GeV)
  • Re-scattering DD*→J/ψω?

BF(B→KY)*BF(Y→J/ψω)=

Belle (7.1±1.3±3.1)*10-5

Babar (4.9±1.0±0.5)*10-5

x 3940 d d and x 4160 d d
X(3940)→DD* and X(4160)→D*D*

Mrec(J/ψD)

DD*D*π

Mrec(J/ψD*)

DD*

ee→J/ψDD*

X(3940) 6.0σ

ee→J/ψD*D*

X(4160) 5.5σ

M=4156 ± 15 MeV

=139 ± 21 MeV

+25

–20

M =3942 ± 6 MeV

=37 ± 12 MeV

+7

–6

M(D*D)

M(D*D*)

+111

– 61

+26

–15

PRL100, 202001 (2008)

  • Reconstruct J/ψ and one D(*),associatedD(*) seen as peak inMrecoil(J/ψD(*))
  • Possible assignments: ηc(3S) ηc(4S)

(but X masses ~100-150MeV above predictions for ηc’s)

CX=+1 so

X(4160)≠ψ(4160)

y j via isr
Y→J/ψππ via ISR

Y(4260)

Y(4008)

PRL 99, 182004 (2007)

  • Study of e+e-→J/ψπ+π- γISR(548 fb-1)
  • J/ψ→ee, μμ + ππ; no extra tracks
  • ISR photon is not detected
  • Missing mass used to identify process
  • Y(4260) confirmed
  • Y(4008) resonance? Re-scattering from DD*? Coupled-channel effect?
y via isr
Y→ψ’ππ via ISR

PRL 99, 142002 (2007)

  • Study of e+e-→ψ’π+π- γISR(673 fb-1)
  • ψ’→J/ψππ, J/ψ→ee, μμ + ππ
  • no additional tracks allowed
  • γISR not detected
  • Two significant peaks in M(ψ’ππ):

one close to Babar’s Y(4360) but narrower

  • M(ψ’ππ)fitted with two coherent Breit-Wigners

Y(4360)

Y(4660)

x sections for e e
x-sections for e+e-→ψππ

J/ψπ+π-

ψ’π+π-

  • ISR allows us to measure hadronic x-sections in wide energy range: model independent measurement
  • M(ψππ): background subtracted, corrected for efficiency and luminosity → Cross-section for e+e-→ψπ+π-
b 0 x 3872 k
B0 →X(3872)K+π–

BELLE-CONF-0849

first observation

X(3872)

sideband

X(3872)→J/ψπ+π–

non-resonant Kπ

K*0→Kπ

Mass(Kπ)

Br(B0→X(K+π–)non_res) Br(X→J/ψπ+π–) = (8.1±2.0+1.1–1.4)10–6

dominates ! unlike B→K”cc”

Br(B0→XK*0)Br(X→J/ψπ+π–) < 3.4x10–6 90% CL

Br(B0→X(K+π–)non res)

Br(B0→XK0s)

~1

ICHEP2008

Galina Pakhlova, ITEP

slide35

B→J/γK & B→(2S)γK

evidence

NEW

B0→XK0s

3.5σ

B±→XK±

confirmation

X(3872)→(2S)γ

3.6σ

B0→XK0s

B0→XK*0

B±→XK*±

B±→XK±

X(3872)→J/γ

B0→XK*0

B±→XK*±

Relatively large Br(X→(2S)γ) is inconsistent with a pure D0D*0 molecular interpretation for X(3872)

Favors cc - D0D*0 mixing models

K = K, K0s, K*(892)

424fb–1

Br(B±→XK±)Br(X→J/γ) = (2.8±0.8±0.2)10–6

Br(B±→XK±)Br(X→(2S)γ) = (9.9±2.9±0.6)10–6

Br(X→(2S)γ) / Br(X→J/γ) = 3.5 ± 1.4

Br(X→(2S)γ) / Br(X→J/π+π–) = 1.1 ± 0.4

HQ session: Arafat G.Mokhtar

ICHEP2008

Galina Pakhlova, ITEP

x 2175 strange analog of y 4260
X(2175) strange analog of Y(4260)?
  • X(2175)→φ f0(980), φη(confirmed by BESII and Belle)

PRD74, 091103 (2006)

hep-ex/0808.0006

hadronic x sections
Hadronic x-sections
  • From CLEO: scan at 3.97-4.26GeV in 12 points
  • Total hadronic x-section above DD from BES
  • Belle: sum of all measured exclusive contributions

(3770)

(4160)

Y(4008)

Y(4350)

(4415)

Y(4260)

Y(4660)

(4040)

Durham Data Base

yb counterpart
Yb counterpart ?

J. Brodzicka @ PIC08

Process Yield σ(pb) BF(%) Г(MeV)

“Y(5S)”→Y(1S)ππ 325±20 1.6±0.1±0.1 0.53±0.03±0.05 0.59±0.04±0.09

“Y(5S)”→Y(2S)ππ 186±15 2.3±0.2±0.3 0.78±0.06±0.11 0.85±0.07±0.16

“Y(5S)”→Y(3S)ππ 10±4 1.4±0.5±0.2 0.48±0.18±0.07 0.52±0.20±0.10

  • M(ππ) and cosθhel studied

Brown-Cahn (CLEO) model (grey)

generic phase space (open)

how to identify b meson signal
How to identify B meson signal

ΔE

Mbc

ΔE

Mbc

  • Advantage of e+e-→(4S) → BBkinematics:

m(4S)~mB+mB no accompanying particles

→ EB=Ebeam=√s/2in cms

  • kinematical variables used in B-Factories

Mbc= √E2beam- p2B

beam-constrained mass

(signal at mB~5.28GeV)

ΔE=EB- Ebeam

cms energy difference

(signal peaks at 0)

  • Resolution improvement

(Ebeam is precisely known)

  • Background separation

Example:

B0→J/ψ KS

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