Exotics as a Probe of Confinement
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Transcript of Exotics as a Probe of Confinement
October 30, 2007ODU Colloquium1
Exotics as a Probe of Confinement Curtis A. MeyerCarnegie Mellon University
QCD Exotics – Past, Present and Future
October 30, 2007ODU Colloquium2
Outline
The beginning of time.
The strong force and QCD
Color confinement
Spectroscopy
Lattice QCD
Finding Gluonic Hadrons
Confinement
October 30, 2007ODU Colloquium3
The First Seconds
of The Universe
October 30, 2007ODU Colloquium4
Quark Gluon Plasma
For a period from about 10-12 s to 10-6 s the universecontained a plasma of quarks, anti quarks and gluons.
Relativistic Heavy Ion Collisions are trying to produce this state of matter in collisions
October 30, 2007ODU Colloquium5
Confinement
From about 10-6 s on, the quark and anti quarks became confined inside of Hadronic matter. At the age of 1s, only protons and neutrons remained.
BaryonsMesons
Flux
tube
forms
between
qqThe gluons producethe 16ton force thatholds the hadronstogether.
October 30, 2007ODU Colloquium6
The Formation of Nuclei
By the old age of three minutes, the formation of low mass nuclei was essentially complete.
Primordial hydrogen, deuterium, helium and afew other light nuclei now exist.
It will be nearly a half a million years beforeneutral atoms will dominate matter.
October 30, 2007ODU Colloquium7
Quantum Chromo
The rules that govern how the quarks froze out into hadrons are given by QCD.
Three charges called RED, BLUE andGREEN, and three anti colors. The objects that form have to be colorneutral:
Just like atoms areelectrically neutral,hadrons have to beneutral.
Color Charge
Dynamics
October 30, 2007ODU Colloquium8
Gluons Carry the Force
G R
RG
G R
Meson Meson
Time
The exchange of gluons is continually changing theIndividual colors of the quarks, but the overallColor remains neutral
R R
G
G
BB
October 30, 2007ODU Colloquium9
Gluons Carry the Force
G R
RG
G R
Meson Meson
Time
The exchange of gluons is continually changing theIndividual colors of the quarks, but the overallColor remains neutral
R R
G
G
BB
October 30, 2007ODU Colloquium10
Gluons Carry the Force
G R
RG
G R
Meson Meson
Time
The exchange of gluons is continually changing theIndividual colors of the quarks, but the overallColor remains neutral
R R
G
G
BB Gluons produce the forces that
confine the quarks, but the gluonsdo not appear to be needed tounderstand normal hadrons
October 30, 2007ODU Colloquium11
Gluon InteractionsG R
RG
RR
G
G
B
B
8 Gluons
3 Colors3 Anti Colors
1 color neutral8 colored objects
RR G
B
B RG
R
self-interaction of gluonsleads to both interestingbehavior of QCD, and itsextreme complications.
October 30, 2007ODU Colloquium12
Flux Tubes
October 30, 2007ODU Colloquium13
Flux TubesFlux
tube
forms
between
Color Field: Because of self interaction, confining flux tubes form between static color charges Confinement arises
from flux tubes and their excitation leads to a new spectrum of mesons
October 30, 2007ODU Colloquium14
• quarks can never be isolated• linearly rising potential
– separation of quark from antiquark takes an infinite amount of energy
– gluon flux breaks, new quark-antiquark pair produced
Quark Confinement
October 30, 2007ODU Colloquium15
See and systems.qq qqq
white
white
Color singlet objects observed in nature:
Allowed systems: , , ggggg, gqq qqqq
Nominally, glue isnot needed to describe hadrons.
s
d
u
s
d
u Focus on “light-quark mesons” quark-antiquark states
Strong QCD
glueballs hybrids
October 30, 2007ODU Colloquium16
Positronium
e+ e-
Spin: S=S1+S2=(0,1)
Orbital Angular Momentum: L=0,1,2,…
Reflection in a mirror: Parity: P=-(-1)(L)
Total Spin: J=L+S L=0, S=0 : J=0 L=0, S=1 : J=1L=1 , S=0 : J=1 L=1, S=1 : J=0,1,2
… …
Particle<->Antiparticle: Charge Conjugation: C=(-1)(L+S)
Notation: J(PC) 0-+, 1--, 1+-, 0++, 1++, 2++ (2S+1)LJ
1S0, 3S1, 1P1, 3P0, 3P1, 3P2,…
SpectroscopyA probe of QED
October 30, 2007ODU Colloquium17
Quarkonium
q q
0-+
1+-
1--
0++1++2++
2-+1--2--3--
4++
2++3++
3+-
S=1S=0L=0
L=1
L=2
L=3
Mesons
Consider the three lightest quarks
sdu ,,sdu ,, 9 Combinations
dduu 2
1
ssdduu 3
1 ssdduu 26
1
duud
susd
usds
radi
al
Spectroscopy and QCD
October 30, 2007ODU Colloquium18
Quarkonium
q q
0-+
1+-
1--
0++1++2++
2-+1--2--3--
4++
2++3++
3+-
S=1S=0L=0
L=1
L=2
L=3
Mesons
,K,,’
,K*,,
b,K,h,h’
a,K,f,f’
,K,,’
,K*,, Mesons come in Nonets of the sameJPC Quantum Numbers
SU(3) is brokenLast two members mix
Spectroscopy an QCD
October 30, 2007ODU Colloquium19
Quantum Mechanical MixingStates with the same quantum numbers mix:
ssdduu 3
11
ssdduu 26
18
SU(3) 8
1
cos
sin
sin
cos
'
f
f
physicalstates
Ideal Mixing:
ss
dduu
f
f 2
1
'
3
1sin
3
2cos
October 30, 2007ODU Colloquium20
Quarkonium
q q
0-+
1+-
1--
0++1++2++
2-+1--2--3--
4++
2++3++
3+-
S=1S=0L=0
L=1
L=2
L=3
Mesons
Quarkonium
Allowed JPC Quantum numbers:
0++ 0-+
1–- 1++ 1+-
2-- 2++ 2-+
3-- 3++ 3+-
4-- 4++ 4-+
5-- 5++ 5+-
0-- 0+-
1-+
2+-
3-+
4+-
5-+
Exotic Quantum Numbersnon quark-antiquark description
Spectroscopy an QCD
Nothing to dowith Glue!
October 30, 2007ODU Colloquium21
1.0
1.5
2.0
2.5
qq Mesons
L = 01 2 3 4
2 + +0 – +2 – +
0 + +G
lueballs
Glueball Predictions
All of these are normalquark-antiquark quantumnumbers.
Particles that only contain gluons
October 30, 2007ODU Colloquium22
Lattice QCD Predictions
Gluons can bind to form glueballs EM analogue: massive globs of pure light.
Lattice QCD predicts masses The lightest glueballs have “normal” quantum numbers.
Glueballs will Q.M. mix The observed states will be mixed with normal mesons.
Strong experimental evidence For the lightest state.
October 30, 2007ODU Colloquium23
Glueballs should decay in a flavor-blind fashion.
0:1:1:4:3':''::: KK
Identification of Glueballs
Lightest Glueball predicted near two states of same Q.N.. “Over population” Predict 2, see 3 states
Production Mechanisms: Certain are expected to by Glue-rich, others are Glue-poor. Where do you see them?
Proton-antiprotonCentral ProductionJ/ decays
October 30, 2007ODU Colloquium24
f0(1500)
f2(1270)
f0(980)
f2(1565)+700,000 000 Events
Crystal Barrel Results: antiproton-proton annihilation at rest
f0(1500)
250,000 0 Events
Discovery of the f0(1500) f0(1500) ’, KK, 4
f0(1370)
Crystal Barrel Results Establishes the scalar nonet
Solidified the f0(1370)
Discovery of the a0(1450)
October 30, 2007ODU Colloquium25
Central Production Experiment
)%90(05.0)1710(
')1710(
14.048.0)1710(
)1710(
03.020.0)1710(
)1710(
16.052.0)1500(
')1500(
07.032.0)1500(
)1500(
84.05.5)1500(
)1500(
21.035.0)1370(
)1370(
90.017.2)1370(
)1370(
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
clf
f
KKf
f
KKf
f
f
f
f
KKf
f
f
KKf
f
KKf
f
Recent comprehensive data setand a coupled channel analysis.
CERN experiment colliding pon a hydrogen target.
Wa102 Results
October 30, 2007ODU Colloquium26
meson
mesonGlueball
meson
mesonmeson
Glueballmeson
meson
1
r2
r3
qqG flavor blind? r
Solve for mixing scheme
ssdduu ,,
F.Close: hep-ph/0103173
A Model for Mixing
October 30, 2007ODU Colloquium27
Experimental Evidence
Scalar (0++) Glueball and twonearby mesons are mixed.
f0(980)
f0(1500)
f0(1370)
f0(1710)
a0(980)
a0(1450) K*0(1430)
Glueballs
Glueball spreadover 3mesons Are there other glueballs?
October 30, 2007ODU Colloquium28
Part of the BES-III program will be to search forglueballs in radiative J/ decays.
Lattice predicts that the 2++ and the 0-+ are the next two, with masses just above 2GeV/c2.
Radial Excitations of the 2++ ground stateL=3 2++ States + Radial excitationsf2(1950), f2(2010), f2(2300), f2(2340)…
2’nd Radial Excitations of the and ’,perhaps a bit cleaner environment! (I wouldNot count on it though….)
I expect this to be very challenging.
Higher Mass Glueballs?
October 30, 2007ODU Colloquium29
Hybrid Meson Predictions
Flux-tube model: 8 degenerate nonets 1++,1-- 0-+,0+-,1-+,1+-,2-+,2+- ~1.9 GeV/c2
S=0
1.0
1.5
2.0
2.5
qq Mesons
L = 01 2 3 4
exoticnonets
0 – +0 + –1 + +1 + –1– +1 – –2 – +2 + –
Hybrids
S=1
Start with S=01++ & 1--
Start with S=10-+ & 0+-
1-+ & 1+-
2-+ & 2+-
qqg
October 30, 2007ODU Colloquium30
QCD Potential
linear potential
ground-state flux-tube m=0
excited flux-tube m=1
Gluonic Excitations provide anexperimental measurement of the excited QCD potential.
Observations of the nonets on the excited potentials are the best experimental signal of gluonic excitations.
October 30, 2007ODU Colloquium31
Flux-tube model: 8 degenerate nonets 1++,1-- 0-+,0+-,1-+,1+-,2-+,2+- ~1.9 GeV/c2
Lattice calculations --- 1-+ nonet is the lightest UKQCD (97) 1.87 0.20MILC (97) 1.97 0.30MILC (99) 2.11 0.10Lacock(99) 1.90 0.20Mei(02) 2.01 0.10Bernard(04) 1.792§0.139In the charmonium sector:1-+ 4.39 0.080+- 4.61 0.11
Splitting = 0.20
1-+ 1.9+/- 0.22+- 2.0+/- 0.110+- 2.3+/- 0.6
S=0 S=1
Hybrid Predictions
October 30, 2007ODU Colloquium32
Looking for Hybrids
Meso
n
Meso
nM
eson
Decay Predictions
Lglue
Angular momentumin the gluon flux stays confined.
This leads to complicatedmulti-particle final states.
Detector needs to be very good.
Analysis MethodPartial Wave Analysis
Fit n-D angular distributionsFit Models of production and decay of resonances.
October 30, 2007ODU Colloquium33
Experimental Evidence
New York Times, Sept. 2, 1997
Hybrids
Exotic Mesons1-+ mass 1.4E852 BNL ’97CBAR CERN ’97
Too lightNot Consistent Possible rescattering (?)Decays are wrong (?)
Not a Hybrid
October 30, 2007ODU Colloquium34
p p
At 18 GeV/c
suggests p 0 p
p
to partial wave analysis
M( ) GeV / c2 M( ) GeV / c2
E852 Results
October 30, 2007ODU Colloquium35
An Exotic Signal
LeakageFrom
Non-exotic Wavedue to imperfectly
understood acceptance
ExoticSignal
1
Correlation ofPhase
&Intensity
M( ) GeV / c2
1(1600)
3 m=1593+-8+28-47 =168+-20+150
-12
’ m=1597+-10+45-10 =340+-40+-50
October 30, 2007ODU Colloquium36
-p ’-p at 18 GeV/c
The 1(1600) is the Dominant signal in ’.Mass = 1.5970.010 GeVWidth = 0.3400.040 GeV 1(1600) ’
E852 Results
In Other Channels
1-+ in ’
October 30, 2007ODU Colloquium37
-p +--p
1(1600) f1
E852 Results
-p 0-p 1(1600) b1
Mass = 1.6870.011 GeV
Width = 0.2060.03 GeV
Mass=1.7090.024 GeV
Width=0.4030.08 GeV
In both b1 and f1, observeExcess intensity at about2GeV/c2.Mass ~ 2.00 GeV, Width ~ 0.2 to 0.3 GeV
In Other Channels1-+ in f1 and b1
October 30, 2007ODU Colloquium38
New Analysis
Dzierba et. al. PRD 73 (2006)
Add 2(1670)-> (L=3)Add 2(1670)->3Add 2(1670)-> ()SAdd a3 decaysAdd a4(2040)
10 times statistics ineach of two channels.
Get a better descriptionof the data via momentscomparison
No Evidence for the 1(1670)
October 30, 2007ODU Colloquium39
1(1400) Width ~ 0.3 GeV, Decays: only weak signal in p production (scattering??) strong signal in antiproton-deuterium.
1(1600) Width ~ 0.16 GeV, Decays ,’,(b1) Only seen in p production, (E852 + VES)
1 IG(JPC)=1-(1-+)
’1 IG(JPC)=0+(1-+)
1 IG(JPC)=0+(1-+)
K1 IG(JPC)= ½ (1-)
1(2000) Weak evidence in preferred hybrid modes f1 and b1
NOT AHYBRID
Doesthis exist?
The rightplace. Needsconfirmation.
Exotic Signals
October 30, 2007ODU Colloquium40
Experimental Evidence
New York Times, Sept. 2, 1997Hybrid
Nonets
dduu 2
1
ssdduu 3
1 ssdduu 26
1
duud
susd
usds
Built on normal mesons
Identify otherstates in nonetto establish hybrid
Establish other Nonets: 0+- 1-+ 2+-
1-+
Levels
October 30, 2007ODU Colloquium41
Jefferson Lab Upgrade
October 30, 2007ODU Colloquium42
CHL-2CHL-2
Upgrade magnets Upgrade magnets and power and power suppliessupplies
Jefferson Lab Upgrade
October 30, 2007ODU Colloquium43
The GlueX Experiment
October 30, 2007ODU Colloquium44
Beams of photons may be a more naturalway to create hybrid mesons.
Simple QN counting leads to the exotic mesons
There is almost no data for photon beams atthese energies. GlueX will increase samples by
3-4 orders of magnitude.
How to Produce Hybrids
October 30, 2007ODU Colloquium45
Coherent
flu
x
photon energy (GeV)
12 GeV electrons
This technique provides requisite energy, flux and
polarization
collimated
Incoherent &coherent spectrum
tagged
with 0.1% resolution
40%polarization
in peak
electrons in
Linearly polarizedphotons out
spectrometer
diamondcrystal
Bremsstrahlung
October 30, 2007ODU Colloquium46
ExoticsExotics
N N
e
X
,,
1 IG(JPC)=1-(1-+)
’1 IG(JPC)=0+(1-+)
1 IG(JPC)=0+(1-+)
K1 IG(JPC)= ½ (1-)
1-+ nonet
Need to establish nonet nature of exotics: 0
Need to establish more than onenonet: 0+- 1-+ 2+-
In Photoproduction
October 30, 2007ODU Colloquium47
Gluonic Hadrons and Confinement
Non-gluonic mesons – ground state glue.
Potentials correspondingTo excited states of glue.
Lattice QCD potentials
What are the light quarkPotentials doing?
E
October 30, 2007ODU Colloquium48
Conclusions
The quest to understand confinement and the strong force is about to make great leaps forward.
Advances in theory and computingwill soon allow us to solve QCDand understand the role of glue.
The definitive experiments toconfirm or refute our expectationsare being built.
The synchronized advances in both areas will allowus to finally understand QCD and confinement.