electron-ion collider · is like colliding swiss watches to find out how they are build.” ... eic...
TRANSCRIPT
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The Physics of a FutureElectron-Ion Collider
Thomas UllrichWorkshop on High-Energy and Nuclear
Physics in the Far FutureRHIC & AGS User Meeting 2010
June 8, 2010
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1897 Discovery of electron Thomson
1909 Atom/Nucleus Rutherford
1913 First Quantum Model of Atoms Bohr
1926 Modern Quantum Model of Atom Schrödinger, de Broglie, Heisenberg, ...
1927 Quantum field theories Dirac, Wolfgang Pauli, Weisskopf, and Jordan
1932 Quantum mechanics as the theory of linear operators
Neumann
1947 Lamb shift ⇒ harbinger of modern QED
Lamb, Rutherford
>1947 Quantum electrodynamics (QED) Feynman, Dyson, Schwinger, Tomonaga
~2004 g-2: aµ(exp) = 11 659 208(6) × 10−10 (0.5 ppm) aµ(SM) = 11 659 181(8) × 10−10 (0.7 ppm)
E821
A Revolution: “Photonic” Structure of Matter
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A Revolution: “Photonic” Structure of Matter
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3
Next Frontier: “Gluonic” Structure of MatterMore Questions than Answers: How do we understand the visible matter in our universe in terms of the fundamental quarks and gluons of QCD?
• Confinement of color, or why are there no free quarks and gluons at a long distance?
• How do quarks and gluons form color neutral hadrons?
• What is the quark-gluon structure inside a hadron?
• How to understand the spin of a hadron?
• What is the physics behind the QCD mass scale?
The key to the answers is the Gluon• It represents the difference between QED and QCD
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4
Understanding QCD ?LQCD = q(iγµ∂µ −m)q − g(qγµTaq)Aa
µ − 14Ga
µνGµνa
• “Emergent” Phenomena not evident from Lagrangian‣ Asymptotic Freedom‣ Confinement ‣ Phases of QCD (T > 0 , µB > 0)
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4
Understanding QCD ?LQCD = q(iγµ∂µ −m)q − g(qγµTaq)Aa
µ − 14Ga
µνGµνa
• “Emergent” Phenomena not evident from Lagrangian‣ Asymptotic Freedom‣ Confinement ‣ Phases of QCD (T > 0 , µB > 0)
• Gluons & their self-interaction‣ Determine essential features of
strong interactions ‣ Dominate structure of QCD vacuum
(fluctuations in gluon fields) ‣ Responsible for > 98% of the visible
mass in universe G. SchierholzAction density in 3q system (lattice)
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4
Understanding QCD ?LQCD = q(iγµ∂µ −m)q − g(qγµTaq)Aa
µ − 14Ga
µνGµνa
• “Emergent” Phenomena not evident from Lagrangian‣ Asymptotic Freedom‣ Confinement ‣ Phases of QCD (T > 0 , µB > 0)
• Gluons & their self-interaction‣ Determine essential features of
strong interactions ‣ Dominate structure of QCD vacuum
(fluctuations in gluon fields) ‣ Responsible for > 98% of the visible
mass in universe G. SchierholzAction density in 3q system (lattice)
Cannot “see” the glue in the low-energy world
Despite this conjectured dominance, properties of gluons in matter remain largely unexplored
⇒ Experiments
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How to Study Gluons in Matter ?
5
Hadron-Hadron
• Test QCD• Probe/Target interaction
directly via gluons • Lacks the direct access to
parton kinematics• Probe has complex structure
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h
h
How to Study Gluons in Matter ?
5
Electron-Hadron (DIS)
• Explore QCD & Hadron Structure
• Indirect access to glue• High precision & access to
partonic kinematics• Probes partons w/o disturbing
them or interfering with their dynamics
h
Hadron-Hadron
• Test QCD• Probe/Target interaction
directly via gluons • Lacks the direct access to
parton kinematics• Probe has complex structure
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h
h
How to Study Gluons in Matter ?
5
Electron-Hadron (DIS)
• Explore QCD & Hadron Structure
• Indirect access to glue• High precision & access to
partonic kinematics• Probes partons w/o disturbing
them or interfering with their dynamics
h
Both are complementary but for precision ⇒ ep, eA
Hadron-Hadron
• Test QCD• Probe/Target interaction
directly via gluons • Lacks the direct access to
parton kinematics• Probe has complex structure
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h
h
How to Study Gluons in Matter ?
5
Electron-Hadron (DIS)
• Explore QCD & Hadron Structure
• Indirect access to glue• High precision & access to
partonic kinematics• Probes partons w/o disturbing
them or interfering with their dynamics
h
Both are complementary but for precision ⇒ ep, eA
Hadron-Hadron
• Test QCD• Probe/Target interaction
directly via gluons • Lacks the direct access to
parton kinematics• Probe has complex structure
“Scattering of protons on protonsis like colliding Swiss watches to find out how they are build.”
R. Feynman
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The Electron Ion Collider
6
• US initiative driven by the QCD community in NP• Colliding
‣Electrons up to 20 (30) GeV‣Hadrons
๏ protons up to 250 GeV๏ ions up to Au/U at 100 GeV
‣with unprecedented luminosities (> 100x Hera)• Unique
‣High energy eA collisions‣Polarized beams: e↑p↑
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EIC Science Case
7
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EIC Science Case
7
• What is the nature and role of gluons and their self-interactions (eA, ep)?‣ Physics of Strong Color Fields (Saturation/non-linear QCD)‣ Study the nature of color singlet excitations (Pomerons)‣ Test and study the limits of universality (eA vs. pA)
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EIC Science Case
7
• What is the nature and role of gluons and their self-interactions (eA, ep)?
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EIC Science Case
7
• What is the internal landscape of the nucleons?‣What is the nature of the spin of the proton?‣What is the Three-Dimensional Spatial Landscape of Nucleons?
• What is the nature and role of gluons and their self-interactions (eA, ep)?
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EIC Science Case
7
• What is the internal landscape of the nucleons?
• What is the nature and role of gluons and their self-interactions (eA, ep)?
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EIC Science Case
7
• What is the internal landscape of the nucleons?
• What is the nature and role of gluons and their self-interactions (eA, ep)?
• What governs the transition of quarks and gluons into pions and nucleons?‣ How do fast probes interact with the gluonic medium? ‣ Mechanism of fragmentation?
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EIC Science Case
7
• What is the internal landscape of the nucleons?
• What is the nature and role of gluons and their self-interactions (eA, ep)?
• What governs the transition of quarks and gluons into pions and nucleons?
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EIC Science Case
7
• What is the internal landscape of the nucleons?
• What is the nature and role of gluons and their self-interactions (eA, ep)?
• What governs the transition of quarks and gluons into pions and nucleons?
‣ Parity Violating deep inelastic scattering (PVDIS)‣ Lepton Flavor and Number Violation
• Electroweak Physics (studies underway)
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EIC Science Case
7
• What is the internal landscape of the nucleons?
• What is the nature and role of gluons and their self-interactions (eA, ep)?
• What governs the transition of quarks and gluons into pions and nucleons?
• Electroweak Physics (studies underway)
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EIC Science Case
7
• What is the internal landscape of the nucleons?
• What is the nature and role of gluons and their self-interactions (eA, ep)?
• What governs the transition of quarks and gluons into pions and nucleons?
• Electroweak Physics (studies underway)
Required Measurements:‣ Momentum distribution of gluons ‣ Spatial distribution of gluons
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8
Deep Inelastic Scattering (DIS)
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p fraction of struck quark
Inelasticity:
quark+anti-quarkmomentum distributions
gluon momentum distribution
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�F2: The Key Structure Function
9
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F2: The Key Structure Function
9
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![Page 26: Electron-Ion Collider · is like colliding Swiss watches to find out how they are build.” ... EIC Science Case 7 ... ‣ Study the nature of color singlet excitations (Pomerons)](https://reader030.vdocument.in/reader030/viewer/2022040405/5e9a70fe60f6771b372ad482/html5/thumbnails/26.jpg)
F2: The Key Structure Function
9
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![Page 27: Electron-Ion Collider · is like colliding Swiss watches to find out how they are build.” ... EIC Science Case 7 ... ‣ Study the nature of color singlet excitations (Pomerons)](https://reader030.vdocument.in/reader030/viewer/2022040405/5e9a70fe60f6771b372ad482/html5/thumbnails/27.jpg)
F2: The Key Structure Function
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![Page 28: Electron-Ion Collider · is like colliding Swiss watches to find out how they are build.” ... EIC Science Case 7 ... ‣ Study the nature of color singlet excitations (Pomerons)](https://reader030.vdocument.in/reader030/viewer/2022040405/5e9a70fe60f6771b372ad482/html5/thumbnails/28.jpg)
F2: The Key Structure Function
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F2: The Key Structure Function
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Quark and Gluon Distributions
10
Structure functions allows us to extract the quark q(x,Q2) and gluon g(x,Q2) distributions. In LO: Probability to find parton with x, Q2 in proton
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Quark and Gluon Distributions
10
Structure functions allows us to extract the quark q(x,Q2) and gluon g(x,Q2) distributions. In LO: Probability to find parton with x, Q2 in proton
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Quark and Gluon Distributions
10
Structure functions allows us to extract the quark q(x,Q2) and gluon g(x,Q2) distributions. In LO: Probability to find parton with x, Q2 in proton
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/"NO% >?GL@:B?%043CGL4:44404?
GL4:4440@0GL4:444?CB
GL4:4442GL4:444CGL4:444@B?GL4:444M
GL4:440B
GL4:44?0
f(x, Q21)→ f(x, Q2
2)
pQCD+DGLAP Evolution
• F2
• dF2 /dlnQ2 ⇒ +
![Page 33: Electron-Ion Collider · is like colliding Swiss watches to find out how they are build.” ... EIC Science Case 7 ... ‣ Study the nature of color singlet excitations (Pomerons)](https://reader030.vdocument.in/reader030/viewer/2022040405/5e9a70fe60f6771b372ad482/html5/thumbnails/33.jpg)
Quark and Gluon Distributions
10
!"!#$ "!#% "!#& "!#" "
'()*+#,'-./'0123456
'37132893:;<4'=:>32;<8:;?
'9@A34'=:>32;<8:;?
7
7B
'C&'D'"!'E3F&
()*+'G;2=>;=23'/=:>;8@:H'I@2J8:K'E2@=1L=>45'-M?H5'N'"O"#"O&'0&!!O6'PQRS"
T7=
T7A
'7K'0U"V&!6
'7G'0U"V&!6
!5&
!5$
!5S
!5O
"
Structure functions allows us to extract the quark q(x,Q2) and gluon g(x,Q2) distributions. In LO: Probability to find parton with x, Q2 in proton
![Page 34: Electron-Ion Collider · is like colliding Swiss watches to find out how they are build.” ... EIC Science Case 7 ... ‣ Study the nature of color singlet excitations (Pomerons)](https://reader030.vdocument.in/reader030/viewer/2022040405/5e9a70fe60f6771b372ad482/html5/thumbnails/34.jpg)
Quark and Gluon Distributions
10
!"!#$ "!#% "!#& "!#" "
'()*+#,'-./'0123456
'37132893:;<4'=:>32;<8:;?
'9@A34'=:>32;<8:;?
7
7B
'C&'D'"!'E3F&
()*+'G;2=>;=23'/=:>;8@:H'I@2J8:K'E2@=1L=>45'-M?H5'N'"O"#"O&'0&!!O6'PQRS"
&!
$
O
"&
"S
'7K
'7G
T7=
T7A
Structure functions allows us to extract the quark q(x,Q2) and gluon g(x,Q2) distributions. In LO: Probability to find parton with x, Q2 in proton
Proton is almost entirely glue by x<0.1 (for Q2 = 10 GeV2)
![Page 35: Electron-Ion Collider · is like colliding Swiss watches to find out how they are build.” ... EIC Science Case 7 ... ‣ Study the nature of color singlet excitations (Pomerons)](https://reader030.vdocument.in/reader030/viewer/2022040405/5e9a70fe60f6771b372ad482/html5/thumbnails/35.jpg)
Evolving Picture of Proton
11Time
Valence Quark
Valence Quark
Valence Quark
![Page 36: Electron-Ion Collider · is like colliding Swiss watches to find out how they are build.” ... EIC Science Case 7 ... ‣ Study the nature of color singlet excitations (Pomerons)](https://reader030.vdocument.in/reader030/viewer/2022040405/5e9a70fe60f6771b372ad482/html5/thumbnails/36.jpg)
Evolving Picture of Proton
11Time
Valence Quark
T. Toll MC@NLO BNL 12/03/20095
![Page 37: Electron-Ion Collider · is like colliding Swiss watches to find out how they are build.” ... EIC Science Case 7 ... ‣ Study the nature of color singlet excitations (Pomerons)](https://reader030.vdocument.in/reader030/viewer/2022040405/5e9a70fe60f6771b372ad482/html5/thumbnails/37.jpg)
Evolving Picture of Proton
11Time
Valence Quark
T. Toll MC@NLO BNL 12/03/20096
![Page 38: Electron-Ion Collider · is like colliding Swiss watches to find out how they are build.” ... EIC Science Case 7 ... ‣ Study the nature of color singlet excitations (Pomerons)](https://reader030.vdocument.in/reader030/viewer/2022040405/5e9a70fe60f6771b372ad482/html5/thumbnails/38.jpg)
Evolving Picture of Proton
11
T. Toll MC@NLO BNL 12/03/20097
Time
Valence Quark
Sea Quark
![Page 39: Electron-Ion Collider · is like colliding Swiss watches to find out how they are build.” ... EIC Science Case 7 ... ‣ Study the nature of color singlet excitations (Pomerons)](https://reader030.vdocument.in/reader030/viewer/2022040405/5e9a70fe60f6771b372ad482/html5/thumbnails/39.jpg)
Evolving Picture of Proton
11Time
Valence Quark
T. Toll MC@NLO BNL 12/03/20099
Photon ProbeQ2
![Page 40: Electron-Ion Collider · is like colliding Swiss watches to find out how they are build.” ... EIC Science Case 7 ... ‣ Study the nature of color singlet excitations (Pomerons)](https://reader030.vdocument.in/reader030/viewer/2022040405/5e9a70fe60f6771b372ad482/html5/thumbnails/40.jpg)
Issues with our Current UnderstandingLinear DGLAP Evolution Scheme• Low Q2
‣ G(x, Q2) < Qsea(x, Q2) ?‣ G(x, Q2) < 0 ?
12
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Issues with our Current UnderstandingLinear DGLAP Evolution Scheme• Low Q2
‣ G(x, Q2) < Qsea(x, Q2) ?‣ G(x, Q2) < 0 ?
12
• Large Q2
‣ built in high energy “catastrophe”‣ G rapid rise violates unitary bound
10-4 10-3 10-2 10-1
x
xg(
x,Q
2 )
20
15
10
5
0
Q2 = 200 GeV2
Q 2 = 20 GeV 2
Q 2 = 7 GeV 2
Q2 = 1 GeV2
ZEUS NLO QCD fittot. error (!s free)tot. error (!s fixed)
uncorr. error (!s fixed)
ZEUS, PRD 67, 012007
![Page 42: Electron-Ion Collider · is like colliding Swiss watches to find out how they are build.” ... EIC Science Case 7 ... ‣ Study the nature of color singlet excitations (Pomerons)](https://reader030.vdocument.in/reader030/viewer/2022040405/5e9a70fe60f6771b372ad482/html5/thumbnails/42.jpg)
Issues with our Current UnderstandingLinear DGLAP Evolution Scheme• Low Q2
‣ G(x, Q2) < Qsea(x, Q2) ?‣ G(x, Q2) < 0 ?
12
!"#"$%"&'("
%)%*+,-./-01.23,"-,42)%"
$%"56"
789:;"
<=>9"
$%" 65?7
Linear BFKL Evolution Scheme‣ Density along with σ grows as a
power of energy‣ Can densities & σ rise forever?‣ Black disk limit: σtotal ≤ 2 π R2
• Large Q2
‣ built in high energy “catastrophe”‣ G rapid rise violates unitary bound
10-4 10-3 10-2 10-1
x
xg(
x,Q
2 )
20
15
10
5
0
Q2 = 200 GeV2
Q 2 = 20 GeV 2
Q 2 = 7 GeV 2
Q2 = 1 GeV2
ZEUS NLO QCD fittot. error (!s free)tot. error (!s fixed)
uncorr. error (!s fixed)
ZEUS, PRD 67, 012007
![Page 43: Electron-Ion Collider · is like colliding Swiss watches to find out how they are build.” ... EIC Science Case 7 ... ‣ Study the nature of color singlet excitations (Pomerons)](https://reader030.vdocument.in/reader030/viewer/2022040405/5e9a70fe60f6771b372ad482/html5/thumbnails/43.jpg)
Issues with our Current UnderstandingLinear DGLAP Evolution Scheme• Low Q2
‣ G(x, Q2) < Qsea(x, Q2) ?‣ G(x, Q2) < 0 ?
12
!"#"$%"&'("
%)%*+,-./-01.23,"-,42)%"
$%"56"
789:;"
<=>9"
$%" 65?7
Linear BFKL Evolution Scheme‣ Density along with σ grows as a
power of energy‣ Can densities & σ rise forever?‣ Black disk limit: σtotal ≤ 2 π R2
• Large Q2
‣ built in high energy “catastrophe”‣ G rapid rise violates unitary bound
10-4 10-3 10-2 10-1
x
xg(
x,Q
2 )
20
15
10
5
0
Q2 = 200 GeV2
Q 2 = 20 GeV 2
Q 2 = 7 GeV 2
Q2 = 1 GeV2
ZEUS NLO QCD fittot. error (!s free)tot. error (!s fixed)
uncorr. error (!s fixed)
ZEUS, PRD 67, 012007
Something’s wrong:Gluon density is growing too fast⇒ Must saturate (gluons recombine)What’s the underlying dynamics?
Strong hints that our current understandingof QCD is incomplete.
Low-x realm of the hadronic wave functionrequire a complete new approach
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Saturation/Color Glass Condensate
13
In transverse plane: nucleus/nucleon densely packed with gluons
McLerran-Venugopalan Model:• Weak coupling description of the
wave function • Gluon field Aµ~1/g ⇒ gluon fields
are strong classical fields!• Most gluons kT ~ QS
kT ~ Qs
![Page 45: Electron-Ion Collider · is like colliding Swiss watches to find out how they are build.” ... EIC Science Case 7 ... ‣ Study the nature of color singlet excitations (Pomerons)](https://reader030.vdocument.in/reader030/viewer/2022040405/5e9a70fe60f6771b372ad482/html5/thumbnails/45.jpg)
Saturation/Color Glass Condensate
13
Y =
ln 1
/x
non-
pert
urba
tive
regi
on
ln Q2
ln Q2s(Y)
saturation region
BK/JIMWLK
DGLAP
BFKL
ln !2QCD
"s << 1"s ~ 1Non-Linear Evolution: • At very high energy: recombination compensates gluon splitting• Cross sections reach unitarity limit • BK/JIMWLK: non-linear effects ⇒ saturation ‣ characterized by Qs(x,A) ‣ Wave function is Color Glass Condensate in IMF description
In transverse plane: nucleus/nucleon densely packed with gluons
McLerran-Venugopalan Model:• Weak coupling description of the
wave function • Gluon field Aµ~1/g ⇒ gluon fields
are strong classical fields!• Most gluons kT ~ QS
![Page 46: Electron-Ion Collider · is like colliding Swiss watches to find out how they are build.” ... EIC Science Case 7 ... ‣ Study the nature of color singlet excitations (Pomerons)](https://reader030.vdocument.in/reader030/viewer/2022040405/5e9a70fe60f6771b372ad482/html5/thumbnails/46.jpg)
Saturation/Color Glass Condensate
13
Y =
ln 1
/x
non-
pert
urba
tive
regi
on
ln Q2
ln Q2s(Y)
saturation region
BK/JIMWLK
DGLAP
BFKL
ln !2QCD
"s << 1"s ~ 1
Terra Incognita
Non-Linear Evolution: • At very high energy: recombination compensates gluon splitting• Cross sections reach unitarity limit • BK/JIMWLK: non-linear effects ⇒ saturation ‣ characterized by Qs(x,A) ‣ Wave function is Color Glass Condensate in IMF description
In transverse plane: nucleus/nucleon densely packed with gluons
McLerran-Venugopalan Model:• Weak coupling description of the
wave function • Gluon field Aµ~1/g ⇒ gluon fields
are strong classical fields!• Most gluons kT ~ QS
![Page 47: Electron-Ion Collider · is like colliding Swiss watches to find out how they are build.” ... EIC Science Case 7 ... ‣ Study the nature of color singlet excitations (Pomerons)](https://reader030.vdocument.in/reader030/viewer/2022040405/5e9a70fe60f6771b372ad482/html5/thumbnails/47.jpg)
14
Scattering of electrons off nuclei: Probes interact over distances L ~ (2mN x)-1
For L > 2 RA ~ A1/3 probe cannot distinguish between nucleons in front or back of nucleon Probe interacts coherently with all nucleons
Raison d'être for e+A
“Expected”Nuclear Enhancement Factor(Pocket Formula):
Enhancement of QS with A ⇒ non-linear QCD regime reached at significantly lower energy in nuclei€
(QsA )2 ≈ cQ0
2 Ax
⎛
⎝ ⎜
⎞
⎠ ⎟
1/3
![Page 48: Electron-Ion Collider · is like colliding Swiss watches to find out how they are build.” ... EIC Science Case 7 ... ‣ Study the nature of color singlet excitations (Pomerons)](https://reader030.vdocument.in/reader030/viewer/2022040405/5e9a70fe60f6771b372ad482/html5/thumbnails/48.jpg)
eA: Key to Studying Saturation
15
Electron-Ion Collider (EIC)• Instead extending x, Q reach ⇒ increase Qs
• More sophisticated analyses (constrained by data) confirm pocket formula
× 500
1/x
Q 2 (
GeV
2 )
1
0.1
10
10 2
10 3
10 4
10 5
10 6
Au (ce
ntra
l)
Q2s,g Ca (c
entra
l)
protons
Kowalski and Teaney Phys.Rev.D68:114005,2003
A1/3 ~ 7
Kowalski, Lappi and Venugopalan, PRL 100, 022303 (2008)); Armesto et al., PRL 94:022002; Kowalski, Teaney, PRD 68:114005)
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eA: Key to Studying Saturation
15
Electron-Ion Collider (EIC)• Instead extending x, Q reach ⇒ increase Qs
• More sophisticated analyses (constrained by data) confirm pocket formula
• Strong hints of saturation from RHIC: x ~ 10-3 in Au
• p: No hints at Hera up to x=6.32⋅10-5, Q2 = 1-5 GeV2
× 500
1/x
Q 2 (
GeV
2 )
1
0.1
10
10 2
10 3
10 4
10 5
10 6
Au (ce
ntra
l)
Q2s,g Ca (c
entra
l)
protons
Kowalski and Teaney Phys.Rev.D68:114005,2003
A1/3 ~ 7
Kowalski, Lappi and Venugopalan, PRL 100, 022303 (2008)); Armesto et al., PRL 94:022002; Kowalski, Teaney, PRD 68:114005)
![Page 50: Electron-Ion Collider · is like colliding Swiss watches to find out how they are build.” ... EIC Science Case 7 ... ‣ Study the nature of color singlet excitations (Pomerons)](https://reader030.vdocument.in/reader030/viewer/2022040405/5e9a70fe60f6771b372ad482/html5/thumbnails/50.jpg)
eA: Key to Studying Saturation
15
Electron-Ion Collider (EIC)• Instead extending x, Q reach ⇒ increase Qs
• More sophisticated analyses (constrained by data) confirm pocket formula
• Strong hints of saturation from RHIC: x ~ 10-3 in Au
• p: No hints at Hera up to x=6.32⋅10-5, Q2 = 1-5 GeV2
Finding RHIC and Hera& Qs scalings consistent
× 500
1/x
Q 2 (
GeV
2 )
1
0.1
10
10 2
10 3
10 4
10 5
10 6
Au (ce
ntra
l)
Q2s,g Ca (c
entra
l)
protons
Kowalski and Teaney Phys.Rev.D68:114005,2003
A1/3 ~ 7Hera
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Measurements & Techniques• Gluon Distribution G(x,Q2)
‣ Scaling violation in F2: δF2/δlnQ2
๏ day 1 measurements (inclusive DIS)‣ FL ~ xG(x,Q2)
๏ requires running at wide range of √s‣ 2+1 jet rates
๏ sensitive dominantly to large x‣Diffractive vector meson production ([xG(x,Q2)]2 )
๏ most sensitive method
• Space-Time Distribution‣ Exclusive diffractive VM production (J/ψ, φ, ρ) at Q ~ 0
(photoproduction)๏ Gluonic form factor of nuclei
16
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EIC Science Case
17
• What is the internal landscape of the nucleons?
• What is the nature and role of gluons and their self-interactions (eA, ep)?
• What governs the transition of quarks and gluons into pions and nucleons?
• Electroweak Physics (studies underway)
![Page 53: Electron-Ion Collider · is like colliding Swiss watches to find out how they are build.” ... EIC Science Case 7 ... ‣ Study the nature of color singlet excitations (Pomerons)](https://reader030.vdocument.in/reader030/viewer/2022040405/5e9a70fe60f6771b372ad482/html5/thumbnails/53.jpg)
EIC Science Case
17
• What is the internal landscape of the nucleons?
• What is the nature and role of gluons and their self-interactions (eA, ep)?
• What governs the transition of quarks and gluons into pions and nucleons?
• Electroweak Physics (studies underway)
Required Measurements:‣ Exclusive and Semi-inclusive Measurements ‣ Polarized beams: e↑p↑ e↑He3↑ (polarized n!)
![Page 54: Electron-Ion Collider · is like colliding Swiss watches to find out how they are build.” ... EIC Science Case 7 ... ‣ Study the nature of color singlet excitations (Pomerons)](https://reader030.vdocument.in/reader030/viewer/2022040405/5e9a70fe60f6771b372ad482/html5/thumbnails/54.jpg)
12
� =�
q
12Sq
� �� �
+����Sg +
�
q
Lq + Lg
� �� �
Nature of Spin of the Proton ?
18
Is the proton looking like this?ΔG
Lg
ΣqLq
δqΣqΔq
Longitudinal Helicity Sum Rule:
Total u+d+s quark spin
Gluon spin
Angular momentum
(IMF only)
![Page 55: Electron-Ion Collider · is like colliding Swiss watches to find out how they are build.” ... EIC Science Case 7 ... ‣ Study the nature of color singlet excitations (Pomerons)](https://reader030.vdocument.in/reader030/viewer/2022040405/5e9a70fe60f6771b372ad482/html5/thumbnails/55.jpg)
12
� =�
q
12Sq
� �� �
+����Sg +
�
q
Lq + Lg
� �� �
Nature of Spin of the Proton ?
18
Is the proton looking like this?
ΣqΔq
ΔG
Lg
ΣqLq δq
Longitudinal Helicity Sum Rule:
Total u+d+s quark spin
Gluon spin
Angular momentum
(IMF only)
![Page 56: Electron-Ion Collider · is like colliding Swiss watches to find out how they are build.” ... EIC Science Case 7 ... ‣ Study the nature of color singlet excitations (Pomerons)](https://reader030.vdocument.in/reader030/viewer/2022040405/5e9a70fe60f6771b372ad482/html5/thumbnails/56.jpg)
What Do We Know? NLO Fits to World Data
19
Includes: World Data from DIS, SIDIS, pp (incl. Hermes, Compass, RHIC)
DIS
RHIC
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What Do We Know? NLO Fits to World Data
19
Includes: World Data from DIS, SIDIS, pp (incl. Hermes, Compass, RHIC)
DSSH: D. De Florian et al. arXiv:0804.0422
Δuv Δdv Δu Δd Δs Δg ΔΣDSSV 0.813 -0.458 0.036 -0.115 -0.057 -0.084 0.242
Big questions:• ΔG = ∫Δg(x) dx
‣ no measurements below x ~ 5⋅10-2
• How do we access Lq and Lg in the IMF?
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σ = σ[F2(x,Q2), FL(x, Q2), g1(x, Q2), g2(x, Q2)]
Impact of EIC: g1
20
• longitudinal polarization probes mainly g1
•g1 has partonic interpretation like F1 but now in terms of pol. PDFs
![Page 59: Electron-Ion Collider · is like colliding Swiss watches to find out how they are build.” ... EIC Science Case 7 ... ‣ Study the nature of color singlet excitations (Pomerons)](https://reader030.vdocument.in/reader030/viewer/2022040405/5e9a70fe60f6771b372ad482/html5/thumbnails/59.jpg)
σ = σ[F2(x,Q2), FL(x, Q2), g1(x, Q2), g2(x, Q2)]
Impact of EIC: g1
20x
• longitudinal polarization probes mainly g1
•g1 has partonic interpretation like F1 but now in terms of pol. PDFs
![Page 60: Electron-Ion Collider · is like colliding Swiss watches to find out how they are build.” ... EIC Science Case 7 ... ‣ Study the nature of color singlet excitations (Pomerons)](https://reader030.vdocument.in/reader030/viewer/2022040405/5e9a70fe60f6771b372ad482/html5/thumbnails/60.jpg)
σ = σ[F2(x,Q2), FL(x, Q2), g1(x, Q2), g2(x, Q2)]
Impact of EIC: g1
20x
• longitudinal polarization probes mainly g1
•g1 has partonic interpretation like F1 but now in terms of pol. PDFs
positive Δg
![Page 61: Electron-Ion Collider · is like colliding Swiss watches to find out how they are build.” ... EIC Science Case 7 ... ‣ Study the nature of color singlet excitations (Pomerons)](https://reader030.vdocument.in/reader030/viewer/2022040405/5e9a70fe60f6771b372ad482/html5/thumbnails/61.jpg)
σ = σ[F2(x,Q2), FL(x, Q2), g1(x, Q2), g2(x, Q2)]
Impact of EIC: g1
20
Anticipated precision for one beam energy combinationIntegrated Lumi: 5fb-1 ~ 1 week data takingx
• longitudinal polarization probes mainly g1
•g1 has partonic interpretation like F1 but now in terms of pol. PDFs
![Page 62: Electron-Ion Collider · is like colliding Swiss watches to find out how they are build.” ... EIC Science Case 7 ... ‣ Study the nature of color singlet excitations (Pomerons)](https://reader030.vdocument.in/reader030/viewer/2022040405/5e9a70fe60f6771b372ad482/html5/thumbnails/62.jpg)
σ = σ[F2(x,Q2), FL(x, Q2), g1(x, Q2), g2(x, Q2)]
Impact of EIC: g1
20
Anticipated precision for one beam energy combinationIntegrated Lumi: 5fb-1 ~ 1 week data taking
• longitudinal polarization probes mainly g1
•g1 has partonic interpretation like F1 but now in terms of pol. PDFs
• Constraints ΔG down too x ~ 10-3-10-4
• Allows precision study of Bjorken sum rule
� 1
0dx[gp
1(x,Q2)− gn1 (x, Q2)] =
gA
6(1− αs
π− ...)
(rare example of a well understood fundamental quantity in QCD)
![Page 63: Electron-Ion Collider · is like colliding Swiss watches to find out how they are build.” ... EIC Science Case 7 ... ‣ Study the nature of color singlet excitations (Pomerons)](https://reader030.vdocument.in/reader030/viewer/2022040405/5e9a70fe60f6771b372ad482/html5/thumbnails/63.jpg)
Beyond Spin: Full 3D Imaging of Proton
21
Generalized Parton DistributionsX. Ji, D. Mueller, A. Radyushkin (1994-‐1997)
Structure functions,quark longitudinalmomentum (PDF) & helicity distributions
+
Proton form factors, transverse charge & current densities
=
Correlated quark momentum and helicity distributions in transverse space - GPDs
![Page 64: Electron-Ion Collider · is like colliding Swiss watches to find out how they are build.” ... EIC Science Case 7 ... ‣ Study the nature of color singlet excitations (Pomerons)](https://reader030.vdocument.in/reader030/viewer/2022040405/5e9a70fe60f6771b372ad482/html5/thumbnails/64.jpg)
Hq, E
q, H
q, E
q
GPDs ⇒ Orbital Momentum L
22
GPDs: (~ = pol.)
• Can be studied at EIC using hard exclusive processes• 1st moments can be calculated on lattice• GPDs are defined in the proton rest frame (not IMF!)
12
= Jqz + J
gz =
12
�
q
∆q +�
q
Lqz + J
gz
Jqz =
12
�
q
∆q +�
q
Lqz
=12
�x(Hq + E
q)dx
Note: No separation between Δg and Lg
• Ji’s Sumrule:
|t→0
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Hq, E
q, H
q, E
q
GPDs ⇒ Orbital Momentum L
22
GPDs: (~ = pol.)
• Can be studied at EIC using hard exclusive processes• 1st moments can be calculated on lattice• GPDs are defined in the proton rest frame (not IMF!)
|t→0
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Measurements to Constraint GPDs• Quantum number of final state selects different GPDs:
‣DVCS (γ): H, E, H, E‣ pseudo-scaler mesons: H, E‣ vector-mesons: H, E
• Need wide x and Q2 range to extract GPDs• Need sufficient luminosity to bin in multi-dimensions
~ ~~ ~
dσ
dt∝ e−Bt
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EIC Science Case
24
EIC
QCD Theory
Nuclear
Structure
Hadron Structure
(JLAB 12 GeV, RHIC-Spin)
Relativistic
Heavy Ion Physics
(RHIC, LHC & FAIR)
Technology FrontierExamples: beam cooling,
energy recovery linac,
polarized electron source,
superconducting RF
cavities
High Energy
Physics(LHC, LHeC,
Cosmic Rays)
Condensed
Matter Physics Bose-Einstein Condensate
Spin Glasses
Graphene
Lattice QCD
New Generation
of Instrumentation
Physics of Strong
Color Fields
ab initio
QCD Calculations
& Computational
Development
Understanding
of Initial Conditions,
Saturation,
Energy Loss
Valence Sea
Spin Structure
GPDsTMDs Saturation Models
Color Glass Condensate
Fundamental
Symmetries
P Violation,
Lepton Number
Violation
Non-linearity,
Confinement,
AdS/QCD
QCD
Background,
PDFs
Gluonic Structure
of Nuclei, Nuclear Breakup
A unique opportunity for fundamental physics:
• Increasing Global Interest in ep/eA Facilities‣ LHeC (CERN)‣ EIC (BNL/JLAB)‣ ENC (FAIR)
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EIC Concepts: BNL & JLAB
25
eRHIC = RHIC + Energy-Recovery Linac
ELIC = CEBAF + Hadron Ring
Coherent
e-cooler
eRHIC detector
injec
tor
See talk by Vladimir Litvinenko
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EIC Outlook
26
NSAC Long Range Plan 2007“An Electron-Ion Collider (EIC) with polarized beams has been embraced by the U.S. nuclear science community as embodying the vision for reaching the next QCD frontier.”
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EIC Outlook
• Increasing efforts at BNL & JLAB
26
NSAC Long Range Plan 2007“An Electron-Ion Collider (EIC) with polarized beams has been embraced by the U.S. nuclear science community as embodying the vision for reaching the next QCD frontier.”
![Page 71: Electron-Ion Collider · is like colliding Swiss watches to find out how they are build.” ... EIC Science Case 7 ... ‣ Study the nature of color singlet excitations (Pomerons)](https://reader030.vdocument.in/reader030/viewer/2022040405/5e9a70fe60f6771b372ad482/html5/thumbnails/71.jpg)
EIC Outlook
• Increasing efforts at BNL & JLAB• Concepts of eRHIC and ELIC are taking shape
‣ Substantial progress in machine & IR design
26
NSAC Long Range Plan 2007“An Electron-Ion Collider (EIC) with polarized beams has been embraced by the U.S. nuclear science community as embodying the vision for reaching the next QCD frontier.”
![Page 72: Electron-Ion Collider · is like colliding Swiss watches to find out how they are build.” ... EIC Science Case 7 ... ‣ Study the nature of color singlet excitations (Pomerons)](https://reader030.vdocument.in/reader030/viewer/2022040405/5e9a70fe60f6771b372ad482/html5/thumbnails/72.jpg)
EIC Outlook
• Increasing efforts at BNL & JLAB• Concepts of eRHIC and ELIC are taking shape
‣ Substantial progress in machine & IR design• Staged approach most promising path
‣ Much can be done already at lower energy (e.g. FL)‣ Saturation physics will require full ELIC/eRHIC
26
NSAC Long Range Plan 2007“An Electron-Ion Collider (EIC) with polarized beams has been embraced by the U.S. nuclear science community as embodying the vision for reaching the next QCD frontier.”
![Page 73: Electron-Ion Collider · is like colliding Swiss watches to find out how they are build.” ... EIC Science Case 7 ... ‣ Study the nature of color singlet excitations (Pomerons)](https://reader030.vdocument.in/reader030/viewer/2022040405/5e9a70fe60f6771b372ad482/html5/thumbnails/73.jpg)
EIC Outlook
• Increasing efforts at BNL & JLAB• Concepts of eRHIC and ELIC are taking shape
‣ Substantial progress in machine & IR design• Staged approach most promising path
‣ Much can be done already at lower energy (e.g. FL)‣ Saturation physics will require full ELIC/eRHIC
• At minimum one large multi-purpose detector
26
NSAC Long Range Plan 2007“An Electron-Ion Collider (EIC) with polarized beams has been embraced by the U.S. nuclear science community as embodying the vision for reaching the next QCD frontier.”
![Page 74: Electron-Ion Collider · is like colliding Swiss watches to find out how they are build.” ... EIC Science Case 7 ... ‣ Study the nature of color singlet excitations (Pomerons)](https://reader030.vdocument.in/reader030/viewer/2022040405/5e9a70fe60f6771b372ad482/html5/thumbnails/74.jpg)
EIC Outlook
• Increasing efforts at BNL & JLAB• Concepts of eRHIC and ELIC are taking shape
‣ Substantial progress in machine & IR design• Staged approach most promising path
‣ Much can be done already at lower energy (e.g. FL)‣ Saturation physics will require full ELIC/eRHIC
• At minimum one large multi-purpose detector• ePHENIX/eSTAR under evaluation
26
NSAC Long Range Plan 2007“An Electron-Ion Collider (EIC) with polarized beams has been embraced by the U.S. nuclear science community as embodying the vision for reaching the next QCD frontier.”
![Page 75: Electron-Ion Collider · is like colliding Swiss watches to find out how they are build.” ... EIC Science Case 7 ... ‣ Study the nature of color singlet excitations (Pomerons)](https://reader030.vdocument.in/reader030/viewer/2022040405/5e9a70fe60f6771b372ad482/html5/thumbnails/75.jpg)
EIC Outlook
• Increasing efforts at BNL & JLAB• Concepts of eRHIC and ELIC are taking shape
‣ Substantial progress in machine & IR design• Staged approach most promising path
‣ Much can be done already at lower energy (e.g. FL)‣ Saturation physics will require full ELIC/eRHIC
• At minimum one large multi-purpose detector• ePHENIX/eSTAR under evaluation• Next Key Event:
‣ INT Workshop: Gluons and the Quark Sea at High Energies: Sep-Nov, 2010 ⇒ Science Case for EIC
26
NSAC Long Range Plan 2007“An Electron-Ion Collider (EIC) with polarized beams has been embraced by the U.S. nuclear science community as embodying the vision for reaching the next QCD frontier.”