Study on Exotic Hadrons at B-Factories

Toru IijimaNagoya University

February 5, 2010NFQCD 10

Talk Outline

Experimental talk to introduce the status on cc-like mesons, recently found at B-factories.

• Introduction• Exotics found in B decays• Exotics found in other processes• XYZ counterparts in b/s sectors.

2

Apologies:I cannot cover all of the results. Too many ! Presentation made mainly using Belle data.

Achievement of the B-factories

3

B0 tag_B

0 tag

Belle 2006 (532M BB)

sin2f1= 0.642 ±0.031 (stat) ±0.017 (syst)

Quest in low-energy QCDAre there exotics beyond meson(qq) /baryon (qqq) ?

We like to answer based on QCD

QCD just require hadrons to be colorless, and allow exotics. Why we don’t see them ?

New Hadrons（ Exotics）Tetra-quark Penta-quark Molecule

4

6 quark model

q qq

q q

meson baryonOrdinal Hadrons

c tu

d s b

up

down

charm

strange

top

bottom

I II IIIq=u, d, s, c, b, t

flavor

color （ R,G,B）

Sakata Model(p, n, L)

Gell-mann(u,d,s)

New Hadrons from B-factoriese+e- B factory is the ideal tool also to study new hadrons w/ heavy flavors !

Bonus discovery at B-factories

hc’ & e+e-ccccD0*0 & D1*0

X(3872)

Sc* baryon triplet

X(3940), Y(3940)

cc2’

Y(4660) Y(4008)

DsJ(2700)Xcx(3090)

Z(4430)

DsJ(2317/2460)

DsJ(2860)

Y(4260)

Y(4320)

Discoveries of new resonances at Belle

Inte

grat

ed lu

min

osity

(fb-1

)

6

7

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: 2.111034cm-2s-1

Integrated luminosity: 950 fb-1

710 fb-1 @ (4S) ~ 800 * 106 BB

~ 960 * 106 cc

Belle at KEKB

B-factory is also a charm factory

553fb-1 at BaBar

Characteristic of the B-factory

• Acceptance: 0.9 ×4p• Vertex resolution

s(J/y ll) ~75nm• Momentum resolution

s(Pt) = 0.19・ Pt 0.34/b %

• Energy resolutions(Eg)/Eg =1.8% @

1GeV• Particle ID

e, m, p, K, p• Minimum bias trigger

Evis >= 1GeV & Ntrk >= 2

& Ncluster >= 4 essentially no loss for BB.

8

9

• B meson decays:

B→Xcc K (BF~10-3)

• initial state radiation (ISR)

e+e-→γISRXcc →γISR ψππ

Production of cc in B Factory

B X=ηc χc ψ… W

K

b c u, d c

s u, d

• double cc production e+e-→J/ψXcc

• γγ collision

e+e-→γγ→Xcc→DD

e+ J/ψ

X e-

c γ* c c c

e+

e-

π π

ψ

γISR γ*

X e+ e+

e- e-

X D D

γ

γJPC(X)=1--

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

J(X)=0, 2 C(X)=+1

Good experimental environment to search for new resonances

Z(4430), Y(4140)

Y(4140), Y(4350)

XYZ found at B-factories

10

• ~15 states have been claimed.• X(3872) has been the most

extensively studied.– JPC = 1++ or 2+-

– Decay to J/ y p p, J/ y g, DD*.

• Charged states require the minimum configuration of ccud. – Z(4430)+ y’p+

– Z(4051)+, Z(4248)+ cc1 p+

• Candidates of s- and b- counterparts – Y(2175)ff0(980)– Yb(10890)U(nS)pp

Charmonia• All charmonium states below the

DD threshold have been observed.– Most are narrow.– Spectra are in good agreement

with naïve quark model

• Above DD threshold– Many states are still empty– Expected to be broad and decay

into DD.

• Many of the observed cc-like states DO NOT;– Fit to the predicted spectrum.– Decay into D(*)D(*) final states.

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n(2S+1)LJJ=S+LP=(-1)L+1

C=(-1)L+S

43

SQCDV kr

r

M(M

eV)

JPC

(2S+1)LJ

Open charm thr. y(3770)

(pot. Models)hc

h’c

J/y

y’ cc2 cc1 cc0

hc

y(4415)X(3872)

States found by ISR

12

• Hybrids: cc + excited gluon (excited flux-tube)• Lattice QCD predicts lightest hybrids @ 4.2GeV • Exotic quantum numbers JPC = 0+-, 1-+, 2+-…• Γ(H→DD**) > Γ(H→DD(*) )• Large Γ(H→ ψππ, ψω,… )

Possible Interpretation

cu

cu

πcu

cuu

cu

ccu

π

cuc u

cuucc u

cc

gc

cc

g

Tetraquark

Hybrid

D(*)D(*) Molecule

• Tetraquarks: diquark-antidiquark [cq][cq]• Tightly bound diquarks (gluon exchange)• Decay proceeds with „coloured” quarks rearrange into

„white” mesons

• Molecules: M(cq)M(cq)• Meson and antimeson loosely bound (pion exchange) • Decay: dissociation into constituent mesons

“Di-quark”

X(3872)

13

BK p+p-J/y

M(p+p-J/y)M(J/y)

The 1st observation by Belle

y’

X(3872)

B decay is a gate way to exotic hadrons !

14

X(3872) • X(3872)→J/ψπ+π- observed in B+→X(3872)K+ by Belle • Confirmed by BaBar, CDF, D0

• mX=3871.2±0.5 MeV mX-(mD*0+mD0)=-0.6±0.6MeV Γ<2.3MeV

• M(π+π-) suggests X(3872)→J/ψ ρ (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)

PRL91, 262001 (2003)

M(π+π-)

M(J/ψπ+π-)

152M BB 117M

BB

X(3872) as D(*)D molecule ?N. A. Tornqvist PLB590, 209 (2004). “Deuson”• X(3872) is very close to DD* threshold (3871.2MeV).• Deuteron-like states found to be bound or nearly bound.• Large spatial size.• Hard to decay into non DD* final states• Width given by stability of components (D*)• Important decay should be D0D0p0 D D*

D* D

p

Similar idea by• E. Swanson (2004),• E. Braaten & M. Kusunoki (2004),• M. Volosin (2004),• C. Thomas & F. Close (2008).and others

16

• Study of X(3872)→J/ψπ+π- in B+→XK+ and B0→XK0s

• Similar properties of X(3872) from B+ and B0 decays

X(3872) in B+ vs B0 decayshep-ex/0809.1224

B+→XK+ Ns=125±14 (12σ)

657M BB

M(J/ψπ+π-)

B0→XK0

Ns=30±7 (6.5σ)

First observation!

M(J/ψπ+π-)

Maiani, Polosa et al. If tetra-quark, slight mass difference between /ccuu ccud

M = 4433 ±4 ±2 MeVGtot = 45 +18 +30 MeVNsig =121 ± 30evtsC2/dof=80.2/94.06.5 s

Charged cc-like exoticsZ(4430)+, Z(4051)+ & Z(4248)+

Required Minimum configuration:

17

ccud

M(py’) GeV

Z(4430)BK p± y’

-13 -13

PRL 100, 142001 (2008)

18

• Maximum likelihood fit to the full Dalitz plot• Bψ’π+K amplitude: coherent sum of Breit-Wigner contributions

• All known low-lying K* resonances: k, K*(892), K*(1410), K*0(1430), K*2(1430), K*(1680)

• Fit is made w/ and w/o Zψ’π+ component. • Data favors the fit w/ Zψ’π+ component.

More Recent Results

Significance: 6.4σ

A B

C D

E

M2(ψ’π+)

M2(ψ’π+)

A+C+E=K*veto

2nd peak at m~4.3 GeV/c2 ?

M2 (

ψ’π

+ )

M2(K-π+ )

A CB D E

F

GH

19

Results from Babar

• B→ψ’π+K studied using 413/fb• Mass spectra corrected for efficiency

PRD79, 112001 (2009)

Statistically consistent with Belle data.(χ2/ndf=54.7/58)

Dalitz plot for B0K+ cc1p-

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K*(892)

??

DE sidebands

K*(890)K+p- K0*(1430)K+p-

K2*(1430)

M2(K+p-)

657M BB

R.Mizuk & R.ChistovarXiv:0806.4098Submitted to PRD

M2 (c c

1p- )

Cont’d

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M(χc1π+) for 1.0 < M2(K-p+) < 1.75GeV2

Z1Z2

M(cc1p+) GeV/c2

Two resonances structure is distinctive (favored over one res. at the 5.7 s )

Mass & width

Prod. Br.

Additional charmonium-like states with non-zero charge !

Z+(4430)

Next step• Search for other decay modes

– [cu][cd] tetra-quark? → neutral partner in ψ’π0 expected

– D*D1(2420) molecule? → decay to D*D*π expected

• Angular distribution→　 JPC determination

22

BF(B→KZ)xBF(Z→y(2S)p) = (3.2 ) x10-5+1.8 +5.3-0.9 -1.6

Z+(4430) confirmed

Exotics found in

• Double charm production• Reaction w/ Initial State Radiation

• Two photon processes

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24

ee→J/ψ D*D*X(4160) 5.5σ

M(D*D*)

ee→J/ψ DD*X(3940) 6.0σ

M(D*D)

X(3940) & X(4160) in e+e-→J/ψXcc

PRL100, 202001 (2008)

e+ J/ψ

X e-

c γ* c c c

PRL98, 082001 (2007)

357fb-1

693fb-1

M =3942 ± 6 MeV G=37 ± 12 MeV

+7–6

+26 –15

M=4156 ±15 MeV G=139 ±21 MeV

+25–20

+111 – 61

X-sections much larger than QCD predicted → factory of 0++ and 0-+ charmonia + others

also cc- baryons ?

Search for X→DD* and D*D* in e+e-→J/ψD(*)D*

Possible assignments: ηc(3S) ηc(4S) (but X masses ~100-150MeV above predictions for ηc’s)

+D*D*+DD*

J/yDD

J/yD*DD*D*

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M=4324 ± 24 MeV G =172 ± 33 MeV

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

Y family through ISR PRL 95, 142001 (2005) for 232fb-1

M=4259 ± 8 MeV G =88 ± 23 MeV

+2–6

+6 –4

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

Y(4360)→ψ’ππ

Y(4260)→J/ψππ

PRD74, 091104 (2006)PRL 96, 162003 (2006)for 13pb-1@4.26GeV

e+

e-

π π

ψ

γISR γ*

Y

26

1-- Y→ψππ states via ISR • 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: DD1 decay mode should dominate• Coupled-channel effects • Charm-meson threshold effects

ee→ppJ/y

ee→ppy’

Y(4260)Y(4008)

Y(4360) Y(4660)

Y(4140) J/y f ?

27

[ ][ ]cs cs

1075/

KJB fy

2.7 fb-1

PRL102, 242002 (2009)

(*) (*)s sD DMolecule

Tetra-quark

• CDF

( )s8.3514

2( / ) ( / )[ / ]M J M J GeV cyf y

MeV

MeVM

syststat

syststat

7.37.11

2.19.20.41433.80.5 G

( )( ) 6109.24.30.9

/,)4140(

yJYKYBBr

• Possible partner of X(3872)

* 22 ( ) 4224.6 /SM D MeV c

Search for Y(4140) → J/ y f• 476M BB• B J/y f K

28

21325/

KJB fy

2sBEE D ( )y/JM

Preliminary

( )4.9(4140) 4.47.5 1.9YN s

non BJ/ y f K background

Non-resonant J/ y f: 1 2( ) ( )a bx m x m

Signal at CDF mass

(5.40 0.03)% 6( (4143) , (4143) / ) 6.0 10Br B Y K Y J yf @90%CL

6(9.0 3.4 2.9) 10 CDF

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Belle: search for Y(4140)→J/ψφ in γγ fusion

No Y(4140) signal [but efficiency drops at low J/ψφ mass] New Y(4350)? excited P-wave charmonim? Ds*Ds0* molecule?

Y(4140)→J/ψφ, Y(4350)→J/ψφ ?

MeV

MeVM

1.43.13

7.06.43509.17

1.9

6.41.5

G

( )( )

G

2for3.05.10for1.14.6

4350 7.05.0

1.33.2

P

P

JeVJeV

JYBr ygg

e+e- undetected pt balance required for final state

( )y/JM

Preliminary

( )s9.38.8 2.42.3

825fb-1Y(4140)

30

Are there XYZ counterparts in strangeness and bottom sectors

?

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

PRD74, 091103 (2006) PRD80, 031101 (R) (2009)

XYZ counterparts in b sectors ?• Energy scan: 10.811.0 GeV.• e+e- U(1S) pp , U(2S) pp, U(3S) pp

32

Belle preliminary

More on Yb

• Rb scan by BaBar

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( ) / ( )bR e e bb e es s m m

PRL 102, 012001 (2009)

:10.54 11.20s GeV

A.Ali, C.Hambrock, I.Ahmed, M.Aslam, PLB684, 28 (2010)

Fit w/ predicted YbResonances.

, , ,cos sinb h b u b dY Y Y

, , ,sin cosb l b u b dY Y Y ~ 5m MeVD

If tetraquark ?

• M(pp), cos distibution (Belle)A.Ali, C.Hambrock, M.Aslam arXiv:0912.5016

Yb U(2S) + pp

Fit w/ f0(600), f0(980), f2(1270) and non-reso.

Yb U(1S) + pp

Energy scan in the next FY year under discussion.

Outlook• We are at the stage of findings

these “exotics”. Don’t know yet what they are…

• There will be more to be found.– Near threshold– Bound states ?

• To elucidate, need more detail information about production & decays.– Production rate in each process– Decay modes– Angular distribution

34

cf) talk by R. Faccini at FPCP09

Plenty of states seen with low-stat. and in only one channel.

More analyses using full dataat the present B factories

And much more information at Super B Factories !

Super B Factory

Target luminosity： 8×1035cm-2s-1

Lint = 1050ab-1 ~15x1010 t+t- pairs

Low emittance positrons to inject

e- 2.1 A

e+ 3.7 A

Low emittance gun

Nano-BeamSuperKEKB

Redesign the HER arcs to squeeze the emitance.

New Superconducting / permanent final focusing quads near the IP

Colliding bunches

Low emittance electrons to inject

New positron target / capture section

Replace long TRISTAN dipoles with shorter ones (HER).

TiN coated beam pipe with antechambers

Add / modify rf systemsfor higher currents.

x40 Gain in Luminosity

Machine ParametersKEKB

DesignKEKB Achieved

(): with crabSuperKEKB Nano-Beam

Scheme

by* (mm)(LER/HER) 10/10 6.5/5.9

(5.9/5.9) 0.22/0.22

x (nm) 18/18 18(15)/24 1/1sy(mm) 1.9 1.1 0.034/0.044

xy 0.052 0.108/0.056 (0.101/0.096) 0.07/0.07

sz (mm) 4 ~ 7 6

Ibeam (A) 2.6/1.1 1.8/1.45 (1.62/0.95) 2.96/1.70

Nbunches 5000 ~1500 2500Luminosity (1034 cm-2 s-1) 1 1.76 (1.68) 80

High Current Option includes crab crossing and travelling focus.Nano-Beam Option does not include crab waist.

Belle Upgrade

New Dead time free readout and high speed

computing systems

ECLWave sampling + pure

CsI crystal(endcap) PIDThreshold Aerogel + TOF→　 TOP + Aerogel-RICH

SVD4-lyr DSSD → 6lyr DSSD

(option: striplet / pixel )

CDCSuper small cell

Longer lever arm

KL/m detectionRPC → Scintillator

+SiPM(endcap)

Better background toleranceBetter performance

日本 ,韓国 ,スペイン ,ドイツ ,チェコ ,ポーランド ,オーストリア ,US,インド

日本

日本 ,スロベニア ,US

日本 ,台湾 ,ロシア

日本 ,ロシア , US

Summary

• KEKB/Belle, together with PEP II/BaBar and other exp’s, have observed many new hadron resonances, which cannot be explained by conventional meson pictures.

• Some of them must be exotics, requiring the minimum contents of 4 quarks: ex.) Z(4430)+

• Similar states in s- and b-quark sectors are seen.• A large data sample at hand

– More to be analyzed (more production/decay channels, more topics)

– Will continue providing interesting results in coming years.• In future, Super B factories (+ tau-charm) will provide

– Search for more states.– Study on detail properties of observed states.

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New InitiativeGrant-in-aid for innovative scientific research area

”Elucidation of new hadrons with a variety of flavors”.We welcome your contribution !

Visit our home page !http://www.hepl.phys.nagoya-u.ac.jp/public/new_hadron/index.html

Backup

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From Hadron Physics Point of View

B factory is an ideal place to study “new hadrons” with• High luminosity• Ideal measurements (clean environment, 4-p detector, PID etc.).

At Super-B factory;• More states with different

– Flavor configuration ?– # quarks ?

• Detail property of observed states– Decay modes– Spin, ParityEtc.

42Probing new hadron states w/ flavors

New inter-disciplinary area@ KEKB, LEPS, J-PARC !

c cd

uc cs

u …

s su

ub bu

u …

flavor

#qua

rks

Also,5-quark ?6-quark ?

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Exclusive x-sections with ISR

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

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

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

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

D*D*

DD*

y(4

040)

y(4

160)

Y(4

008)

y(4

415)

Y(4

660)

Y(4

260)

Y(4

350)

DD

DDπ

Λc+Λc

–

?

PRD77,011103(2008)

PRL100,062001(2008)

NEW

PRL98, 092001 (2007)

arXiv:0807.4458

44

How to identify B meson signal • Advantage of e+e-→(4S) → BB kinematics: m(4S)~mB+mB no accompanying particles

→ EB=Ebeam=√s/2 in cms • kinematical variables used in B-Factories

Mbc= √E2beam- p2

B 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

Mbc ΔE

Mbc

ΔE

Example: B0→J/ψ KS