Near-threshold non-qq meson candidates

Stephen Lars OlsenSeoul National University

_Heavy-Quark Hadrons at J-PARC Symposium at Tokyo Inst. Tech., June 22,2012

2

Constituent Quark Model1964 The model was proposed independently by Gell-Mann and Zweig with three fundamental building blocks: 1960’s (p,n,l) Þ 1970’s (u,d,smesons are bound states of a of quark and anti-quark:

baryons are bound state of 3 quarks:

€

π + =ud π 0 = 12(uu − dd ) π - = du

K + = us K 0 = ds K 0 = sd K − = su

€

p = uud n = udd Λ = uds

p = u u d n = u d d Λ = u d s

Gell-Mann

Zwieg

€

π− =du

€

Λ =uds

Google Search: quark: 41,000,000 results (0.13 seconds)

Fabulously successfulQuarks are probably the most

well known particle physics quantityamong the general public

鈴木 一朗 : 2,600,000 results (0.65 seconds)

Superseded by QCD in the 1970s:observed particles are color singlets

Λ= (uds) )( udπ

Mesons are color-anticolorpairsBaryons are red-blue-green triplets

3 primary colors white whitecolor + complementary color

blue-yellowgreen-magenta

red-cyan

QCD has other color-singlet combinations:

Pentaquark: H-diBaryon

Glueball

Tetraquark mesons

qq-gluon hybrid mesons

u cuc

c c

u du

sd

Other possible “white” combinations of quarks & gluons:

_

_

__

u d

usds

_

_ u c

uc

__

_p

D0

D*0_

S=+1 Baryon tightly bound6-quark state

Color-singlet multi-gluon bound state

tightly bounddiquark-diantiquark

loosely boundmeson-antimeson“molecule”

Where are they?

u cuc c c

u du

sd_

___

u d

usds

_ u c

uc

__

_p

D0

D*0_

some history: low-mass scalar mesons

The “light” scalar mesons

JP=0+

800

980a0

- a0+

k+k0

a00

sf0

600

800

800

800

980

k- k0

980

_

the “light” scalar-meson nonet

More “light” scalar-mesons than quark model slots: s, f0(980), f0(1370), f0(1500), f0(1710), f0(1790), …

light scalar nonet: masses are inverted

In qq meson nonets, the I=1 state (here the a0(980)) has no ss content.

No “light” JP=1+ and 2++ partner nonets in the same mass range.

_ _

pseudoscalarsscalars

typical unique

ss-q

uark

con

tent

_

If not qq, then what?_

sqs_

_

q s

qs

__

_s

K

K

_

tightly bounddiquark-diantiquark

loosely boundmeson-antimeson“molecule”

q

Possibilities that have been suggested:

J.D.Weinstein & N.Isgur PRD 27, 588 (1983)

R.L.Jaffe PRD 15, 267 (1977)

In color space:

red+blue=magenta (antigreen)

cyan+yellow=green (antimagenta)

A colored diquarkis like a antiquark

A colored diantiquarkis like a quark

“nuclear” force

Institute of High Energy Physics-- Beijing --

To Tiananmen Square (~10 km)

BESIII BEPC

11

BEPCII storage rings

Beam energy: 1.0 - 2.3 GeVPeak Luminosity: Design:1×1033 cm-2s-1

Achieved:0.65x1033 cm-2s-1

Beam energy measurement: Using Compton backscattering technique. Accuracy: dEbeam/Ebeam ≈ 510– 5

dEbeam ≈ 50 KeV @Ebeam ≈ mt

BESIII Collaboration

>300 physicists

49 institutions from 10 countries

1111

Turkey: Turkish accelerator center

Helmholtz Institute Mainz Johannes Gutenberg-University Mainz

2929

The a0(980) & f0(980) straddle the KK thresholda 0(9

80) (

hp

0 )

2mK

f0(980) K+K-

f0(980) p+p-

2mK

_

a0(980)0 f0(980) mixing

isospin violation enhanced by K0 – K+ mass difference

2mK+ = 987.4 MeV 2mK0 = 995.2 MeV

€

a00 → f0 →π +π − or f0 →a0

0 →ηπ 0

2mK+

2mK0

expect a narrow line shape: G≈2(mK0-mK+)=7.8 MeV

PDG2010: Mf0

= 980 ± 10 MeV f0

= 40 ~ 100 MeV

Ma0= 980 ± 20 MeV

a0= 50 ~ 100 MeV

N.N. Achasov, S.A. Devanin & G.N. Shestakov, Phys. Lett. B88, 367 (1979)

BES study of a0(980)0 f0(980) mixing

BESIII PRD 83, 032003 (2011)

a0(980)0 f0(980) mixing results

different models &parameterizations

KK molecule model_

90% CL upper limits

Statistics limited, but BESIII already has lots more data.

J/f0(980)p0,f0(980)pp

f0(980)00

f1(1285)3.7s f1(1285)

1.2s

f0(980)+-

h(1405) h(1405)

Large Isospin violations:

from helicity analyses

€

BR(η(1405) → f0(980)π 0)

BR(η(1405) →a00(980)π 0)

= (27 ± 6)%

1st observations: (1405)f0(980)p0

& J/ygf0(980)p0

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Bf (J / ′ ψ →γη(1405) →γπ 0 f0 →γπ 0π +π −)

= (1.50 ± 0.11(stat.) ± 0.11(syst.)) ×10−5

€

Bf (J / ′ ψ →γη(1405) →γπ 0 f0 →γπ 0π 0π 0)

= (7.10 ± 0.82(stat.) ± 0.72(syst.)) ×10−6

BESIII PRL 108, 182001 (2012)

Anomalous f0(980) lineshape in h(1405)f0(980)p0

Fitted mass: M”f0” = 989.9 ± 0.4 MeVG”f0” = 9.5 ± 1.1 MeVThe peak is midway between 2mK0 & 2mK+

& width ≈ 2(mK0 - mK+ ) PDG2010: Mf0

= 980 ± 10 MeV f0

=40 ~ 100 MeV

BESIII PRL 108, 182001 (2012)

Effect of Triangle Singularity?J.J.Wu et al, PRL 108, 081803 (2012)

Triangle Singularity (TS) a0—f0 mixing

K*K and KK are on shellenhancing TS contribution

and isospin violation

_ _a0—f0 mixing is too small toexplain anomaly by itself

f0(980) and h(1405) strongly influenced by the nearby KK & KK* thresholds.

_ _

h(1405)

Baryonium at the pp threshold?_

J/y g pp @BESII

This is the hcppthe J/y’s

spin=0 partner

What is this???

M(pp) GeV

BESII PRL 91, 022001 (2003)

Fit the M(pp) distribution

fit with a sub-threshold resonance

_

M(pp) GeV Mpp-2mp (GeV)0 0.1 0.2 0.3

BESII PRL 91, 022001 (2003)

M=1859 MeV/c2

G < 30 MeV/c2 (90% CL)

+3 +5

-10 -25

“cartoon”

real fit

X(1835) has large BR to pp

• BESIII:

• our estimate from unpublished Crystal Ball data:

• implies a huge Br(Xpp):

€

BR(J /ψ →γX(1835)) • BR(X(1835) → pp ) ~ 9 ×10−5

€

BR(J /ψ →γX(1835)) < 2 ×10−3

€

BR(X(1835) → pp ) > 4%

Since decays to pp are only possible from the tail of X(1835), such a BR indicates X(1835) has a huge coupling to pp !

J/y g XXtal Ball(unpublished)

see L.Kopke, N.Wermes,Phys. Rep 174, 67 (1989)

X(3872) meson near the DD* threshold

_

KEK Laboratory, Tsukuba Japan

FukushimaBelle Detector

e- e+

KEKB

Mt Tsukuba

cc meson production in B decays

d1/3

b-1/3 C-2/3

C+2/3

d1/3

S-1/3

W -

K0

“Charmonium”

“spectator”

B0_

_

_

Belle’s main purpose: Measure CP violations with B mesons that decay like this. Nobel prize for Kobayashi &Maskawa in 2008

Charmonium (cc) meson spectrum_

All of the states below 2mD

have been identified

The X(3872) in BK p+p-J/y discovered by Belle (140/fb)

M(ppJ/y) – M(J/y)

y’p+p-J/y

X(3872)p+p-J/y

PRL 91, 262001 (2003)

X(3872)p+p- J/yconfirmed by many experiments

~6000 evts!

MX = 3871.61 ± 0.16 ± 0.19 MeV

MX = 3871.85 ± 0.27 ± 0.19 MeV

MX = 3871.96 ± 0.46 ± 0.10 MeV

CDF

LHCb

Belle: PRD 84 052004

CDF: PRL 103 152001 LHCb: arXiv:1112.5310

Belle

p+p-system in X(3872)p+p-J/ y comes from rp+p-

X3872

r

p+

J/y

p-

CDF: PRL 96 102002

M(p+p- )

M(p+p- )

rp+p- lineshape

Belle: PRD 84 052004

Problem: (cc)r J/y violates Isospinand should be strongly suppressed

_

X(3872) not well matched toany unassigned cc level

3872 MeV

_

X(3872) mass (in p+p-J/ y channel only)

MX(3872) –(MD0 + MD*0) = -0.12 ± 0.35 MeV_

MD0+MD*0=3871.79 ± 0.30 MeV

u c

uc

__

_p

D0

D*0_

D0D*0 molecule??

_

Isospin Violation in X(3872) decay:

≈on mass shell ≈8 MeV off mass shellMX(3872) –(MD+ + MD*-)= -7.74 ± 0.35 MeV

If so, the binding energy is very small

X(3872)-J/y relative sizes

•How can such a fragile object be produced in H.E. pp collisions? heavy ion collisions??

Volume(J/y) /Volume(X3872) ≈ 10-4

-- arXiv 0906.0882: sCDF(meas)>3.1±0.7nb vs stheory(molecule)<0.11nb

_

C. Bignamini et al, PRL 103, 162001:

drms(208Pb nucleus)≈5.5 fm

++ +

++

+

++

++

++

++

++

++

+

208Pb

drms(J/y) ≈ 0.4 fm

drms(X3872) ~ 8 fm

J/y

X(3872)

Venus (x3)

Sun

Very different objects!

Charged Zb1(10,610)+ and Zb2(10,650)+ in the b-quark sector

_

(4S) p+p- (1S) ?

ϒ(4

S)“bottomonium” bb mesons

2MB = 10358.7 MeV

Belle: G(4S)p+p-(1S)

2S3S

4S

(4S) (1S) p+p-

477 fb-1

52±

10 e

vts

N(4S) N(p+p-1S) B(Y4Spp1S) G(Y4Spp1S) Gtheory

535x106 52±10 9 ± 2 x10-5 1.75 ± 0.35 keV 1.47±0.03 keV

Belle: PRD 75 071103

2MB = 10358.7 MeV

(5S) p+p- (1S) ?ϒ

(4S)

ϒ(5

S)

Belle: G(5S)p+ -(p 1S)

23.6 fb-1 vs 477 fb-1~1/20th the data

~1/5ththe cross-section

K.F. Chen et al (Belle) PRL 100, 112001 (2008)

325±20 evts!

“(5S)” is very different from other states

Belle PRL100,112001(2008) (MeV)

X10--2

Anomalous production of (nS) +-

Recall Y(4260) with anomalous (J/ +-)

Is there a Yb equivalent close to (5S)€

Bf (Υ(4S) →π +π −Υ(1S)) = (0.008 ± 0.0003)%

Bf (Y (5S) →π +π −Υ(1S)) = (0.53 ± 0.06)%

“Y(5S)” p-Zb1,2+

p+ϒ(1,2,3S)

ϒ(3S)

ϒ(2S)

ϒ(1S)

M(Υ(nS)π+)max

p-

p+

p+

p+

Zb1(10610)

Zb2(10660)

10,6

10 M

eV10

,660

MeV

“Y(5S)” p-Zb1,2+

p+hb(1,2P)

hb(1P)

hb(2P)

M(hb+)

Zb1(10610)

Zb2(10660)

p-

p+

p+

10,6

10 M

eV10

,660

MeV

Zb(10610)

M=10607.22.0 MeV

=18.42.4 MeV

Zb(10650)

M=10652.21.5 MeV

=11.52.2 MeV

Belle PRL 108, 122001

Summary of parameter measurements

mB+

mB*

2mB*

March 2012

Zb1 & Zb2, “smoking guns” for multiquark mesons

ubd

b decays to ϒ(nS) & hb(nP) must contain bb pair

electrically charged must contain ud pair

_

_

B-B* & B*-B* molecules??

B

B*

b

b

_

B-B* “molecule”

B*

B*

b

b

_

B*-B* “molecule”_ _

_ _

Zb(106010)± Zb(106050)±

MZb(106010) –(MB+MB*) = + 3.6 ± 1.8 MeVMZb(106010) –2MB* = + 3.1 ± 1.8 MeV

Slightly unbound threshold resonances??

M=10608.11.7 MeV

=15.52.4 MeV

M=10653.31.5 MeV

=14.02.8 MeV

PDG: MB + MB* = 10604.50.6 MeV MB* + MB* = 10650.2 1.0 MeV

Belle:

_ _

SummaryLots of new particles & threshold effects found recently

Lots of work for theorists to do…

•KK/KK* thresholds have large influences on f0/a0(980) & h(1405)

•X(1860) near NN threshold pp bound state (baryonium)?

•X(3872) near DD* threshold D0D*0 bound state?

•Zb1(10,610) * Zb2(10660) BB* & B*B* resonances?

_

_ _

_ _

_ _

_

Thank you

감사합니다

どもぅ ありがとぅ

mesons come in nonetsJP=0-

JP=1-

K*0 K*+

K*- K*0_

r0r- r+

f

w

139 139

135548

958

498

498

494

494

896

896

892

892

776776776 783

1020

S-wave

nr=0

S-wave

nr=0

(r+,r0,r-)=lightest(p+,p0,p-)=lightest

49

baryons come in octets & decuplets

M=????MeV

M=1533 MeV

M=1385 MeV

M=1232 MeV

1192

1115

1189

938

1197

939

1321 1315

JP=1/2+ JP=3/2+

all S-waves

all S-wavesall nr=0

all nr=0

?? M=1672 MeVW-

W- not the 1st Baryon correctly predicted

pg 425

1405 MeV

KN threshold

1959!!

R. Dalitz1925-2006

S.F. Tuan

pg 698

mK+mN threshold

L(1405) discovered in 1961

JP=1/2-

Is the L(1405) a uds state?

)2( 23 LnE r

€

⇒ h =(1405 − mΛ) = 290 MeV

There are no octet partners with this Dm

(lowest ½- N* state = N*(1535) )

€

h ≈600 MeV

quark model fails for the 1st baryon foundabove the S-wave octet & decuplet.

€

Λ(1405)⇒ JPC = 12

− ⇒ odd - parity⇒ L =1

Dalitz spent years trying to fit the L(1405) into the quark model, without success