introduction and status of qcd exotics k. peters gsi darmstadt/jwgu frankfurt hadron physics at cosy...

Introduction and Status of QCD Exotics

K. PetersGSI Darmstadt/JWGU Frankfurt

Hadron Physics at COSY 2005Bad Honnef, July 25-29

K. Peters - Status of QCD Exotics

Overview

IntroductionStatus of Spin-ExoticsStatus of Glueball-SearchFuture Experiments

Not coveredPentaquarksBaryoniumCharmonium-Spectrum

What are EXOTIC hadrons ?

Unconventional hadronsDepends on what is the convention

ConventionMatter is build out of quarks

• proton consists of 3 quarks

• pion consists of a quark and an antiquark

UnconventionalHadronic matter is not made entirely out of quarksQuark configurations different from baryons and mesons

But not forbidden !

Classification (Close & Lipkin)

Exotics of the first kind

External quantum numbers unambiguously incompatible with assignment to baryons or mesons

B=1 – baryon-likeQ>2, Q<-1, S<-3, S>0, I>3/2, ....

B=0 – meson-like|Q|>1, I>1, |S|>2, |C|>2, |S-C|>1, ....

Exotics of the second kind

Combination of quantum numbers not allowed for leading Fock-term

Only possible for B=0

JPC = 0--, 0+-,1-+, 2+-, ...cannot be formed by any unexcited qq-System

Exotics of the third kind – Crypto-Exotics

Internal exotic structurelike gluonic excitationslike N-quarks

but no model free signature

approach:overpopulation of hadron multipletsunexpected masses and decay propertiesa well understood conventional

meson picture is mandatory 3

( )14 0

( )54 8

'( )95 7

K( )49 51 S1

( )1300

( 1295)

'(1490 )

K( )14602 S1

( )1800

( )1775

K( )18303 S1

( )77 0

( )78 2

(10 20 )

K*( )89 21 S3

( )1450

( 1420)

( )1680

K *( )14102 S3

( )1320

( )1260

( )1270

( )1285

( )1525

( )1430

( )1400

( )1235

h 1( 1170)

( )1380

( )12701 P1

( )1450

( )1370

( )1710

(1430)1 P3

( )1810

f '2( 2040)

( )19802 P3

L=0 L=1

F ( )0 975

a ( )0 980

f ( )0 1515

1( )1400

1( )1600

( )1410

f ( )2 1565

f ( )2 1640

seen at single decayunam biguousestablished (PDG)

notq q ?!

1 GeV/ c2

2 GeV/ c2

( )1700

(1 650)

( )1700

Meson Spectrum after the LEAR Era

The LEAR Era withthe experiments

@ CERN

• Asterix/Obelix

• Crystal Barrel

• Jetset/PS185

• WA102/Gams@ BNL

• E818/E852@ FNAL

• E760/E835@Serpukhov

• VES/Gams

produced impressive results with high statistics and high resolution

SPIN-PARITY EXOTICS (2nd Kind)Search for Hybrids

Intermediate State Mixing

Many states may contribute to a final state

not only ones with well defined

(already measured) properties

not only expected ones

Many mixing parameters are poorly known

K-phasesSU(3) phases

In additionalso D/S mixing (b1,a1 decays)

Simplest Hybrids

S-Wave+Gluon (qq)8g with ()8=coloured1S0 3S1

combined with a 1+ or 1- gluon

Gluon 1– (TM) 1+(TE)

1S0, 0–+ 1++ 1––

3S1, 1–– 0+- 0–+

1+- 1–+

2+- 2–+

Meson – Hybrid Mixing

Fluxtube Predictions

N. Isgur, R. Kokoski und J. Paton, Phys. Rev. Lett. 54 (1985) 869 and refs thereinF.E. Close und P. R. Page, Nucl. Phys. B443 (1995) 233

(u,d)g

(n,s)g

Light-quark hybrids

recent new determination of exotic 1-+ hybrid mesonimproved staggered fermions (lighter quark masses)quenched and unquenched, Wilson gluon actiona ~ 0.09 fmlightest mass still

above experiment

MILC, hep-lat/0301024

quenched continuum limit

sduf mmmN ,3

sdu mmm 4.0(around strange quark mass)

Rediscovery of the 1(1400)

peak @ 1.4 GeV/ cphasem otion at a tail visible

B N LE 852

^ ( ) 1400

Advantage: I = 1 and no S calars

GeV / c2 4

3.( )770

a2( )1320

^ ( ) 1400

Cr ystalB ar r el

52.500 E.

πp π-η p (and π0η n) pd π-π0η p @ Rest in liq.D2

Proof of evidence for exotic wave - CB

Posit ive (F it - D at a)

Ne g a tive

2 (F it - D at a)

no 1 in F it

1 in F it

GeV / c2 4

Cr ystalBar r el

Controversary in E852

FSI Description in ηπ-

Szczepaniak, et al., PRL 91, 092002 (2003)

Controversary in E852, cont‘d

in E852 in ηπ0

the amplitudes are different for different regions

BW solution fails

π1(1400) Summary

1400 MeV/c2 region well establishedphase motion against a2(1320) in πp

interference with ρ(770) in pd @ rest

signal in πη is at b1π and f1π thresholdinfluences resultsline shapes and pole positions affected

exotic wave is evidentit might span over a wide rangeis it a Hybrid? probably not – decuplet state?

E852 ρπ

BN LE 852

(X - 1 )- +

1 (I =1) 1 (I =1)

π-p π-ρ0p π-π-π+pshows a clear resonance in the 1-+ wave around 1600 MeV/c2

VES η‘π

resonant structurein η‘π at 1600 MeV/c2

in ηπ at 1400 MeV/c2

η and η‘ are coupled via SU(3) any interpretation of the π1

resonances have to explain the

difference

Verificationof πη(') resultsin ρπ channel

ρ(16xx) observedby two independentexperiments in ρπand η‘π

(2 - 1 )++ - +

V ES , H adron ‘95 /’97

V E SI ( J ) = 1 (1 )G PC - - +

1(14 0 0 )

1(16 0 0 )

E852 f1π and b1π

blue one 1-+ poleblack two poles2=70.6/47=1.5

E852 more b1π

first observation of a non 1-+ exotic

h2(1950) with JPC=2+-

M=1954±8Γ=138±3

another h2 may be at M=2300

Spin-exotic Summary

thanks to G. Adams, RPI

Charmed Hybrids

LQCD: gluonic excitations of the quark-antiquark-potential may lead to bound states-potential

• for one-gluon exchange-potential

• from excited gluon flux

mHcc ~ 4.2-4.5 GeV/c2

Light charmed hybridscould be narrow if open charm decays are inaccessible or suppressed

important <r2> and rBreakup

V(R)/GeV

GLUEBALLS(usually 3rd Kind)

SU(N) Glueballs on the Lattice

recent study of 0++,2++, 0++* glueballs in SU(N), N=2,3,4,5

masses depend linearly on N large N limits differ little from N=3

Lucini, Teper, JHEP 06, 050 (2001).

Morningstar und Peardon, PRD60 (1999) 034509Morningstar und Peardon, PRD56 (1997) 4043

f0(1500) – Crystal Barrel @ LEAR

f0(1500) is very narrow (~100 MeV/c2) and decays dominantly to (2n)π

und p 2 @ Ruhep 0 p 3p 0

G eV / c2 4

m ( )2 1 2 m ( )2

712.000 E.

1. 2. 3.

f (1350)0

f (1500)0

f (1550)2

f (1270)2

f (975)0

C B , A ker et a l., P LB 260(1991)249C B , A m sle r et a l., PLB 342(1995)433

f ( 1350)0

f ( 1500)0

a (980)0

211.000 E .MeV / c2 4

MeV / c2 4

C B , A m sle r et a l., PLB 291(1992)347C B , A m sle r et a l., PLB 353(1995)571

1500 MeV

ein K beobachtetein K durch fehlende Masse

p p K KL L0

m (K )/GeV /2 0 2 4L c

12.515

17.520

1550 1600 1650 1700m(,) MeV

Einträ

3000x 103

1200 1300 1400 1500 1600 1700x 10

3m(0,)2

m(, )2

/MeV/c2 4

p ’p

fj(1710) in radiative J/ decays

Mark III and DM2found a scalar resonance @ 1700 MeV/c2

in KK in radiative decays of the J/

It took more than a decade to establish the scalar nature of this object

MarkIII

SOZI - DOZI - Analysis

SOZI DOZI

DOZISOZI

MarkI I I

f0(1500) in 4π and

fj(1710) in KK

.........“DOZI”-enhanced

......... both should contain remarkable gg content

f,f' (q )q

DOZI suppression forconventional qq

Central Production

CERN-experiments:WA76, WA91, WA102Important results in the

scalar (ππ,KK,KsKs,4) tensor (ππ,KK,KsKs,4)pseudoscalar (KKπ,ππη) sectors

But: ~ 1/M2

no charm-sectorpartial wave (moment)-

analysis complicated little фф,ωω statistics

Future:Compass, much

higher statistics

Pomeron-Pomeron

PSee-Quark-Formation

Meson Glueball Mixing

Physical Massesf0(1370),f0(1500),f0(1710)

Bare Masses:m1,m2,mG

( )uu dd

(G) (S) (N)f0(1370) -0.690.07 0.150.01 0.700.07f0(1500) -0.650.04 0.330.04 –0.700.07f0(1710) 0.390.03 0.910.02 0.150.02

m1=137720 m2=167410 mG=144324

octet piece

Lattice of about 1600

Anisovich & Sarantsev

Anisovich and Sarantsev, hep-ph/0204328

K-Matrix approach M= 280 – 1900 MeV

Uses data from GAMS at small and large nucleon momentumE852CERN-Munich scatteringCrystal Barrel

For the channels ππ, ηη, ηη‘, KK, ππππNo f0(600) = σ

Found f0(980), f0(1300), f0(1500),

f0(1750) and f0(1200-1600)

DS+ π+π-π+ (+c.c)

E.M. Aitala et al., PRL 765 (2001)

B. Lewandowski, Proc. Meson 2002PHD Th. Deppermann, Bochum 2003

848 E.

2903 E.PRELIMINARY

non-unitary approach needs interference of 4 resonances for the strange peak K-Matrix approach resolves it

D+ π+π-π+ (+c.c)

E791E.M. Aitala et al., PRD 770 (2002)

1172 E.

non-unitary approach yields 50% σ K-Matrix approach removes any σ contribution

Problems in Analysis and Interpretation

many processes, therefore no trivial production amplitude

coupled channels contain very many production amplitudes

complicated interferences

in K0SK0

S contr. from K0K0 and K0K0

direct FSI

directFSI

I=0, KK* or c.c._

no only K0K0*+c.c.Wc

ColorS

The scalar particles

most interpretations assume the doubtless K0*(1430) from LASS to be the I=1/2-state

and that the a0(1400) is the I=1-state

two classes of arrangementsa00(980) & f0(975) are isospin-partner

a0(980) & f0(975) are completely independent

a reasonable model must be able to handle the mixing of isoscalars

as well as t- and u-channel exchange

Scalar Summary

Puzzle still unsolved ....

re vie w

1.8 2.2

f (19 2 0 )2

f (18 10 )2

f (19 8 0 )2

(2 2 3 0 )

f (2 3 5 0 )2f (2 2 0 0 )2

f (2 0 5 0 )2

G .I.-Sta te s

0 ?+ +

2 GeV Tensors

Sorted by measured final state

Structure unclear

f2(1920)

1.6 2.0 2.4GeV/c2

1.6 1.8 2.0

GeV/c2

cos <0.5

cos >0.5

all p cex.-

’ ’

t<0.06 0.2<t<0.35

0.35<t<0.6

f2(2200)

MarkI I I

rad. J /

K KS S4K±

K K 2K±L S

MarkI I I

rad. J /

K KS S4K±

K K 2K±L S

c. prod.

t<0.06

Broad resonanceat 2.2 GeV/c2

K KS S

SUMMARY and OUTLOOK I

Hybrids

Many Spin-Parity Exoticsπ1(1400) ***

π1(1600) ****

π1(2000) **

h2(1950) *

h2(2300) (*)

Future investigationsGlueX for the light quark sectorPanda for the onia and heavy light sector

SUMMARY and OUTLOOK II

Glueballs

Too many scalars with an unclear natureexperimental situation fairly good, saturatedD(s)-decays can not help solving this issue

Many unconfirmed tensorsimportant field for the future to settle the spectrumBESIII and Panda are well suited

FUTURE EXPERIMENTS

π-p X0n

exotic/non-exotic ~ 1exotic/non-exotic ~ 0.1

Szczepaniak & Swat (01)

photon

γp X+n

Possible narrow QCD exotic (M=1.6 GeV) (E852 π-p π+π-π-p)

Implications for exotic meson searches

CHL-2CHL-2

Upgrade magnets Upgrade magnets and power and power suppliessupplies

Hall D @ JLab and the 12 GeV Upgrade

Construction start - 200?Physics - 200?+4

The GSI Future Facility

Existing GSI Facilities

0 2 4 6 8 12 1510

p Momentum [GeV/c]

Mass [GeV/c2]

Two bodythresholds

Molecules

GluonicExcitations

qq Mesons

1 2 3 4 5 6

Hybrids

Hybrids+Recoil

Glueball

Glueball+Recoil

ΛΛΣΣΞΞ

ΛcΛc

ΣcΣc

ΞcΞc

ΩcΩcΩΩ DDDsDs

qqqq ccqq

nng,ssg ccg

ggg,gg

light qqπ,ρ,ω,f2,K,K*

ccJ/ψ, ηc, χcJ

nng,ssg ccg

Accessible Charmed Hadrons at PANDA @ GSI

Other exotics with identical decay channels same region

conventionalcharmonium

exoticcharmonium

BES III @ BEPC2

BEPC2 will operate as τcf and synchrotron light source

Start of operation 2007

Beam energy 1 – 2.1 GeV

Optimal energy 1.89 GeV

Luminosity 1 x 10 33 cm-2s-1 @ 1.89 GeV

Linac requirements Full energy injection: 1.55 1.89 GeV Positron injection rate > 50 mA/min

Dedicated SR 250 mA @ 2.5 GeV

BES III Physics Performance Example

J/ψρ0ηπ0

Well identified ρ(1390) ρ(2300)via partial waveanalysis

introduction and status of qcd exotics k. peters gsi darmstadt/jwgu frankfurt hadron physics at cosy...

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