Nucleon Structure Study with e-N
Jian-ping Chen (陈剑平), Jefferson Lab, Virginia, USA
EIC 物理研讨会 ,Weihai, China, July 29, 2013
 Introduction
 Polarized e-N facilities: JLab/12 GeV, EIC, …
 Examples of Golden Physics Cases
Spin Structure
3-d Structure of the Nucleon (GPDs, TMDs)
p/K Structure Functions
others: Form Factor, Hadron Spectroscopy, Parity Violation e-N
 Unique Opportunities for EIC@HIAF
Introduction
Nucleon Structure ,QCD and e-N
Major Challenge: Non-perturbative QCD/Confinement
• 2004 Nobel prize for
``asymptotic freedom’’
• non-perturbative regime QCD ?
confinement
• One of the top 10 challenges for
physics!
• QCD: Important for discovering
new physics beyond SM
• Nucleon structure is one of the
most active areas
running coupling “constant”
History of Nucleon Structure Study
 1933: First (Indirect) Evidence of Proton Structure
magnetic moment of the proton: mp=eћ/2mpc(1+kp) !
anomalous magnetic moment: kp= 1.5 +- 10%
Otto Stern
Nobel Prize 1943
 1960s: Discovery: Proton Has Internal Structure
elastic electron scattering
 1970s: Discovery of Quarks (Partons)
deep-inelastic scattering
Robert Hofstadter,
Nobel Prize 1961
 1970s-2000s: Parton Distributions
 1980s-2010s: Spin Distributions
 2000s-: 3-d Structure
J.T. Friedman
R. Taylor
Nobel Prize 1990
H.W. Kendall
Nucleon Structure: A Universe Inside
•
Nucleon: proton =(uud) ,
+ sea + gluons
•
Global properties and structure: full of surprises
Mass: 99% of the visible mass in universe
~1 GeV, but u/d quark mass only a few MeV each!
Lattice QCD: vacuum condensation
Charge and magnetic distributions: very different
Momentum: quarks carry ~ 50%
Spin: ½, but total quarks contribution only ~30%
Orbital angular momentum is important
Transverse (3-d) structure: GPDs and TMDs …
neutron=(udd)
Nucleon Structure Function: Deep-Inelastic Scattering
•
•
•
Bjorken Scaling and Scaling Violation
Gluon radiation – QCD evolution
One of the best experimental tests of QCD
QCD and Nucleon Structure Study
•
Dynamical Chiral Symmetry Breaking <-> Confinement ?


•
Rapid development in theory




•
Responsible for ~98% of the nucleon mass
Higgs mechanism is (almost) irrelevant to light quarks
Lattice QCD
Dyson-Schwinger
Ads/CFT: Holographic QCD
……
Direct comparisons limited to
 Moments
 Tensor charge
 …
•
Direct comparison becomes possible
 Experimental data with predictions
from theory
C.D. Roberts, Prog. Part. Nucl. Phys. 61 (2008) 50
M. Bhagwat & P.C. Tandy, AIP Conf.Proc. 842 (2006) 225-227
Mass from nothing!
Imaging dynamical chiral symmetry breaking: pion wave function on the
light front, Lei Chang, et al., arXiv:1301.0324 [nucl-th], Phys. Rev.
Lett. 110 (2013) 132001 (2013) [5 pages].
C.D. Roberts, Prog. Part. Nucl. Phys. 61 (2008) 50
Dyson-Schwinger
Pion’s valence-quark
Distribution Amplitude
Dilation of pion’s wave
function is measurable in
pion’s electromagnetic form
factor at JLab12
A-rated: E12-06-10
 Established an one-to-one connection between DCSB and the pointwise form of the pion’s
wave function.
 Dilation measures the rate at which dressed-quark approaches the asymptotic bare-parton
limit
 Experiments at JLab12 can empirically verify the behaviour of M(p), and hence chart the IR
limit of QCD
Craig Roberts: Mapping Parton Structure and Correlations (62p)
Hall-A Collaboration Meeting: 13-14 June 2013
8
New progress in Lattice QCD



Using the Infinite Momentum Frame formalism.
Start with static correlation in the z-direction.
Can be extended to TMDs and GPDs.
First exploratory study by Huey-Wen Lin presented at
the QCD Evolution Workshop at JLab, May 2013.
X. Ji
Lepton-Nucleon Facilities
JLab 6 GeV/12 GeV, EIC
Jefferson Lab at a Glance
CEBAF
A
C
B
A B C
 High-intensity electron
accelerator based on CW
SRF technology
 Emax = 6 GeV 12 GeV
 Imax = 200 mA
 Polmax = 85%
 L~ 1039
(unpolarized)
~ 1036-1037 (polarized)
 ~ 1400 Active Users
 ~ 800 FTEs
 178 Completed Experiments
@ 6 GeV
 Produces ~1/3 of US PhDs
in Nuclear Physics
12 GeV Upgrade
The completion of the 12 GeV
Upgrade of CEBAF was
ranked the highest priority in
the 2007 NSAC Long Range
Plan.
New Hall
Add 5
cryomodules
20 cryomodules
CHL-2
Add arc
20 cryomodules
Add 5
cryomodules
Enhanced capabilities in
existing Halls
High Luminosity
1035 - ~1039 cm-2s-1
Maintain capability to deliver
lower pass beam energies :
2.2, 4.4, 6.6,….
JLab Physics Program at 12 GeV
Hall A – form factors, GPDs & TMDs , SRC
Hall A
Low-energy tests of the SM and Fund. Symmetry Exp
SoLID,
Hall B
MOLLER.
High luminosity, high resolution &
dedicated equipments
Hall B - 3-D nucleon structure via GPDs & TMDs
Search new form of hadron. matter via Meson Spectr.
4p detector
Hall C – precision determination of valence quark
Hall C
properties in nucleons and nuclei
Hermetic detector
Photon tagger
high momentum spectrometers &
dedicated equipments
Hall D
Hall D - exploring origin of confinement by studying exotic
mesons using real photons
13
H1, ZEUS
H1, ZEUS
COMPASS
11 GeV
HERMES
The 12 GeV Upgrade is well
matched to studies in the
valence quark regime.
0.7
EIC: Science Motivation
A High Luminosity, High Energy Electron-Ion Collider:
A New Experimental Quest to Study the Sea and Glue
How do we understand the visible matter in our universe
in terms of the fundamental quarks and gluons of QCD?
Precisely image the sea-quarks and gluons in the nucleon:
• How do the gluons and sea-quarks contribute to the spin
structure of the nucleon?
• What are the 3d distributions of the gluons and sea quarks in
the nucleon?
• How do hadronic final-states form in QCD?
Explore the new QCD frontier: strong color fields in nuclei:
• How do the gluons contribute to the structure of the nucleus?
• What are the properties of high density gluon matter?
• How do fast quarks or gluons interact as they traverse nuclear
matter?
2010 NRC Decadal Study
Electron Ion Colliders on the World Map
EIC@HIAF
LHC 
LHeC
RHIC 
eRHIC
CEBAF 
MEIC/EIC
HERA
FAIR  ENC
17
The Landscape of EIC
• An EIC aims to study gluon dominated matter.
• With 12 GeV we study mostly the
valence quark component
mEIC
EIC
12 GeV
Lepton-Nucleon Facilities
HIAF: e(3GeV) +p(12GeV), both polarized, L(max)=4*1032cm2/s
JLAB12
HIAF
Figure of Merit
•
Figure-of Merit for double polarization
FOM=L * Pe2 * PN2 * D2
L=Luminosity, P=Polarization, D=Dilution
•
FOM Comparison of EIC@HIAF (1) with COMPASS (2)
HIAF: L=4*1032, D=1
COMPASS: L=1032, D=0.13 (NH3 target)
Unpolarized:
FOM(1)/FOM(2) = L(1)/L(2) ~ 4
Polarized:
FOM(1)/FOM(2) = L(1)/L(2) * [D(1)2 /D(2)2] ~ 200
Medium Energy EIC@JLab
JLab Concept
Initial configuration (MEIC):
• 3-12 GeV on 20-100 GeV ep/eA collider
• Fully-polarized, longitudinal and transverse
• Luminosity: up to few x 1034 e-nucleons cm-2 s-1
Upgradable to higher energies
250 GeV protons + 20 GeV electrons
MEIC: Full Acceptance Detector
7 meters
detectors
solenoid
ion dipole w/ detectors
IP
0 mrad
2+3 m
2m
2m
Three-stage detection
Central detector
TOF
Solenoid yoke + Hadronic Calorimeter
2m
3m
2m
Muon Detector
Hadron Calorimeter
Tracking
EM Calorimeter
RICH or DIRC/LTCC
RICH
HTCC
EM Calorimeter
Solenoid yoke + Muon Detector
4-5m
electrons
electron FFQs
50 mrad
Detect particles with
angles down to 0.5o
before ion FFQs.
Need 1-2 Tm dipole.
Detect particles with
angles below 0.5o beyond
ion FFQs and in arcs.
Need 4 m machine
element free region
Very-forward detector
Large dipole bend @ 20 meter from IP (to correct the 50
mr ion horizontal crossing angle) allows for very-small
angle detection (<0.3o).
Need 20 m machine element free region
MEIC Point Design Parameters
Detector type
Full acceptance
high luminosity & Large
Acceptance
Proton
Electron
Proton
Electron
Beam energy
GeV
60
5
60
5
Collision frequency
MHz
750
750
750
750
Particles per bunch
1010
0.416
2.5
0.416
2.5
Beam Current
A
0.5
3
0.5
3
Polarization
%
> 70
~ 80
> 70
~ 80
Energy spread
10-4
~3
7.1
~3
7.1
RMS bunch length
mm
10
7.5
10
7.5
Horizontal emittance, normalized
µm rad
0.35
54
0.35
54
Vertical emittance, normalized
µm rad
0.07
11
0.07
11
cm
10 and 2
10 and 2
4 and 0.8
4 and 0.8
Vertical beam-beam tune shift
0.014
0.03
0.014
0.03
Laslett tune shift
0.06
Very small
0.06
Very small
7
3.5
4.5
3.5
Horizontal and vertical β*
Distance from IP to 1st FF quad
Luminosity per IP, 1033
m
cm-2s-1
5.6
14.2
Ongoing MEIC Accelerator R&D
• Space Charge Dominated Ion Beam in the Pre-booster
 Simulation study is in progress by Argonne-NIU collaborators
• Beam Synchronization
 A scheme has been developed; SRF cavity frequency tunability study is in progress
• Beam-Beam Interaction
 Phase 1 simulation study was completed
• Interaction Region, Chromaticity Compensation and Dynamic Aperture




Detector integration with IR design has been completed, offering excellent acceptance
Correction scheme has been developed, and incorporated into the IR design
Tracking simulations show excellent momentum acceptance; dynamic aperture is increased
Further optimization in progress (e.g., all magnet spaces/sizes defined for IR +/- 100 m)

• Beam Polarization
 Electron spin matching and tracking simulations are in progress, achieving acceptable equilibrium
polarization and lifetime (collaboration with DESY)
 New ion polarization scheme and spin rotators have been developed (collaboration with Russian
group) – numerical demonstration of figure-8 concept with misalignments ongoing
• Electron Cloud in Ion Ring
• Ion Sources (Polarized and Universal)


Proposed Cooling Experiments at IMP
DC cooler
• Idea: pulse the beam from the existing thermionic gun
using the grid (Hongwei Zhao)
• Non-invasive experiment to a user facility
Proposed experiments
• Demonstrate cooling of a DC ion beam by a bunched
electron cooling (Hutton)
Two storage rings for Heavy
ion coasting beam
• Demonstrate a new phenomena: longitudinal
bunching of a bunched electron cooling (Hutton)
• (Next phase) Demonstrate cooling of bunched ion
beams by a bunched electron beam
(need
an RF cavity for bunching the ion beams)
EIC Realization Imagined
Activity Name
2010 2011 2012 2013 2014 2015 2016 2017 2018 2019 2020 2021 2022 2023 2024 2025
12 GeV Upgrade
FRIB
EIC Physics Case
NSAC LRP
EIC CD0
EIC Machine
Design/R&D
EIC CD1/Downsel
EIC CD2/CD3
EIC Construction
Assumes endorsement for an EIC at the next NSAC Long Range Plan
Assumes relevant accelerator R&D for down-select process done around 2016
Phase Space for Polarized Data/EIC
x = Q2/ys
(x,Q2) phase space directly correlated
with s (=4EeEp) :
@ Q2 = 1 lowest x scales like s-1
@ Q2 = 10 lowest x scales as 10s-1
EIC@HIAF Kinematic Coverage Comparison with JLab 12 GeV
e(3GeV) +p(12GeV), both polarized, L(max)=4*1032cm2/s
EIC@HIAF:
• study sea quarks (x > 0.01)
• deep exclusive scattering at
Q2 > 5-10
• higher Q2 in valance region
• range in Q2 allows study
gluons
plot courtesy of Xurong Chen
Science Goals
The Science of eRHIC/MEIC
Goal: Explore and Understand QCD:
Map the spin and spatial structure of quarks and gluons in nucleons
Discover the collective effects of gluons in atomic nuclei
(role of gluons in nuclei & onset of saturation)
Emerging Themes:
Understand the emergence of hadronic matter from quarks and gluons & EW
The Science of EIC@HIAF
One Main Goal: Explore Hadron Structure
Map the spin-flavor, multi-d structure of sea & valence quarks
Science Case (I): Nucleon Spin-Flavor Structure
Polarized Sea Quark
Three Decades of Nucleon Spin Structure Study
•
1980s: EMC (CERN) + early SLAC
quark contribution to proton spin is very small
DS = (12+-9+-14)% !
‘spin crisis’
•
1990s: SLAC, SMC (CERN), HERMES (DESY)
DS = 20-30%
the rest: gluon and quark orbital angular momentum
spin sum rule: (½)DS + Lq + JG =1/2
(Ji)
others: Jaffe, Chen et al., …
Bjorken Sum Rule verified to <10% level
•
2000s: COMPASS (CERN), HERMES, RHIC-Spin, JLab, … :
DS ~ 30%; DG probably small (~0.1)?, orbital angular momentum significant?
Valence quark structure
Transverse Spin, TMDs
GPDs
Polarized Structure Function/Distributions
33
JLab E99117: Precision
Measurement of A1n at High-x
PRL 92, 012004 (2004) , PRC 70, 065207 (2004)
Physics News Update, Science Now
Science News, Physics Today Update
Planned JLab 12 GeV Experiments
A1p at 11 GeV
}
Sea Quark Polarization
Kinney, Seele
• Spin-Flavor Decomposition of the Light Quark Sea
Access requires s ~ 100-1000 (and good luminosity)
Xiaodong Jiang (Los Alamos) is doing simulation with
parameters of EIC@HIAF
100 days, L =1033, s = 1000
how effective are scaling violations at the EIC…
what about the uncertainties on the x-shape …
Spin-Flavor Study at EIC@HIAF
• Unique opportunity for Ds
energy reach current fragmentation region for Kaon tagging in SIDIS
• Significant improvement for Du_bar, Dd_bar from SIDIS
combination of energy and luminosity
• Increase in Q2 range/precision for g1 (and g2)
constraint on Dg.
Science Case (II): 3-D Structure
Generalized Parton Distributions
5D Dist.
Wpu(x,kT,r ) Wigner distributions (X. Ji )
d2kT drz
d3r
GPDs/IPDs
TMD PDFs
f1u(x,kT), ..
h1u(x,kT) 3D
d2k
T
PDFs
f1u(x), .. h1u(x)
imaging
dx &
Fourier Transformation
d 2 rT
1D
Form
Factors
GE(Q2),
GM(Q2)
3-D Imaging - Two Approaches
TMDs
2+1 D picture in momentum space
Bacchetta, Conti, Radici
GPDs
2+1 D picture in impact-parameter space
QCDSF collaboration
• intrinsic transverse motion
• collinear but long. momentum transfer
• spin-orbit correlations- relate to OAM
• indicator of OAM; access to Ji’s total Jq,g
• non-trivial factorization
• existing factorization proofs
• accessible in SIDIS (and Drell-Yan)
• DVCS, exclusive vector-meson production
3D Images of the Proton’s Quark Content
M. Burkardt PRD 66, 114005 (2002)
uX(x,b )
dX(x,b )
d(x,b )
Ed
Hd
T
T
T
u(x,b )
transverse polarized target
T
b - Impact parameter
T
quark flavor polarization
Needs:
Hu
Eu
Accessed in Single Spin
Asymmetries.
Access GPDs through DVCS x-section & asymmetries
DIS measures at x=0
Accessed by beam/target
spin asymmetry
Quark distribution q(x)
-q(-x)
t=0
Accessed by cross sections
Quark Angular Momentum
→ Access to quark
orbital angular
momentum
CLAS12 - DVCS/BH Target Asymmetry
ep
epg
Longitudinally polarized
target
~
Ds~sinfIm{F1H+x(F1+F2)H...}df
CLAS preliminary
AUL
<Q2> = 2.0GeV2
<x> = 0.2
<-t> = 0.25GeV2
E=5.75 GeV
E = 11 GeV
L = 2x1035 cm-2s-1
T = 1000 hrs
DQ2 = 1GeV2
Dx = 0.05
Detailed differential images from nucleon’s partonic structure
EIC: Gluon size
from J/Y and f
electroproduction
(Q2 > 10 GeV2)
t
[Transverse distribution derived directly from t dependence]
Weiss, Hyde, Horn
Fazio
• Q2 > 10 GeV2
for factorization
• Statistics hungry
at high Q2!
Horn
Hints from HERA:
Area (q + q) > Area (g)
Dynamical models predict difference:
pion cloud, constituent quark picture
-
EIC: singlet quark
size from deeply
virtual compton
scattering
EIC: strange and
non-strange (sea)
quark size from p
and K production
t
Charles Hyde (ODU)
GPD Study at EIC@HIAF
• Unique opportunity for DVMP (pion/Kaon)
flavor decomposition needs DVMP
energy reach Q2 > 5-10 GeV2, scaling region for exclusive light meson production
(JLab12 energy not high enough to have clean meson deep exclusive process)
• Significant increase in range for DVCS
combination of energy and luminosity
• Other opportunities: vector meson, heavy flavors?
Science Case (III): 3-D Structure
Transverse Momentum-Dependent Distributions
(Haiyan Gao’s talk)
Nucleon Structure (TMDs) with SoLID (JLab)
Semi-inclusive Deep Inelastic Scattering
program:
Large Acceptance + High Luminosity
+ Polarized targets
 4-D mapping of asymmetries
 Tensor charge, TMDs …
Lattice QCD, QCD Dynamics, Models.
Solenoidal Large Intensity Device (SoLID)
International collaboration (8 countries,
50+ institutes and 190+ collaborators)
• Rapid Growth in US‐China Collaboration
Chinese Hadron collaboration
(USTC, CIAE, PKU, Tsinghua U, Lanzhou, IMP,+)
- large GEM trackers
- MRPC-TOF
3 A rated SIDIS experiments approved for SoLID
with 2 having Chinese collaborators as
co-spokesperson (Li from CIAE and Yan from USTC)
E12-10-006/E12-11-108, Both Approved with “A” Rating
Mapping of Collins(Sivers) Asymmetries with SoLID
• Both p+ and p• Precision Map in
region
x(0.05-0.65)
z(0.3-0.7)
Q2(1-8)
PT(0-1.6)
• <10% d quark
tensor charge
Collins Asymmetry
The TMD simulation: Projections for SIDIS Asymmetry π+
EIC@HIAF
reach high
precision
similar to
SoLID at
lower x,
higher Q2
region
Hiayan Gao (Duke)
Green (Blue) Points: SoLID projections for polarized NH3 (3He/n) target
Luminosity: 1035 (1036) (1/cm2/s); Time: 120 (90) days
Black points: EIC@HIAF projections for 3 GeV e and 12 GeV p
Luminosity: 4 x 1032 /cm2/s; Time: 200 days
TMD Study at EIC@HIAF
• Unique opportunity for TMD in “sea quark” region
reach x ~ 0.01
• Significant increase in Q2 range for valence region
energy reach Q2 ~40 GeV2 at x ~ 0.4
• Significant increase in PT range
reach >1 GeV (TMD/co-linear overlap region)
Science Case (IV): p/K Structure
p/K Parton Distribution Function in Valence Quark Region
Craig Roberts
(Argonne)
Parton Structure of Hadrons
 Valence-quark structure of hadrons
– Definitive of a hadron – it’s how we tell a proton from a
neutron
– Expresses charge; flavour; baryon number; and other
Poincaré-invariant macroscopic quantum numbers
– Via evolution, determines background at LHC
 Sea-quark distributions
– Flavour content, asymmetry, intrinsic: yes or no?
 Any nontrivial answers are essentially nonperturbative features
of QCD
Craig Roberts: Mapping Parton Structure and Correlations (62p)
Hall-A Collaboration Meeting: 13-14 June 2013
56
Parton Structure of Hadrons
 Light front provides a link with quantum mechanics
– If a probability interpretation is ever valid,
it’s in the infinite-momentum frame
 Enormous amount of intuitively expressive information about
hadrons & processes involving them is encoded in
– Parton distribution functions
– Generalised parton distribution functions
– Transverse-momentum-dependent parton distribution functions
 Information will be revealed by the measurement of these
functions
– so long as they can be calculated
Success of program demands very close collaboration between
experiment and theory
Craig Roberts: Mapping Parton Structure and Correlations (62p)
Hall-A Collaboration Meeting: 13-14 June 2013
57
Pion Valence-quark Distribution
 Need for calculation is emphasized by Saga of pion’s valencequark distribution:
o 1989: uvπ ~ (1-x)1 – inferred from LO-Drell-Yan & disagrees with QCD;
o 2001: DSE- QCD predicts
uvπ ~ (1-x)2
argues that distribution
inferred from data
can’t be correct;
Craig Roberts: Mapping Parton Structure and Correlations (62p)
Hall-A Collaboration Meeting: 13-14 June 2013
58
Pion Valence-quark Distribution
 Need for calculation is emphasized by Saga of pion’s valencequark distribution:
o 1989: uvπ ~ (1-x)1 – inferred from LO-Drell-Yan & disagrees with QCD;
o 2001: DSE- QCD predicts
uvπ ~ (1-x)2
argues that distribution
inferred from data
can’t be correct;
o 2010: NLO reanalysis including
soft-gluon resummation,
inferred distribution agrees
with DSE and QCD
Craig Roberts: Mapping Parton Structure and Correlations (62p)
Hall-A Collaboration Meeting: 13-14 June 2013
59
Simulated errors for DIS events using 5
GeV electron beam on a 25 GeV proton
beam with luminosity
1032cm-2s-1 and 106s running.
 Pion PDF on the
valence-quark domain
High-impact large-x
measurements
– What is the pointwise structure
of Goldstone modes: massless
bound-states of very massive
constituents?
– Currently, a single reanalysis of
an old experiment agrees with
one (DSE) prediction
– Simulations at EIC-kinematics exist:
Holt & Reimer AIP Conf.Proc. 588 (2001) 234-239
 Kaon PDF on the valence-quark domain
– Critical complement to pion: x=1 measures strength of DCSB
– Need simulations @ EIC-kinematics: kaon structure function [p(e,e’Λ)]
Craig Roberts: Meaning of Parton Distributions Tu.31.03 (36p)
2nd Conference on QCD & Hadron Physics
60
p structure simulation for EIC@HIAF
EIC@HIAF projections for 3 GeV e and 12 GeV p
Luminosity: 5 x 1032 /cm2/s; Time:106 seconds
Paul Reimei
(Argonne)
Imaging dynamical chiral symmetry breaking: pion wave function on the
light front, Lei Chang, et al., arXiv:1301.0324 [nucl-th], Phys. Rev.
Lett. 110 (2013) 132001 (2013) [5 pages].
C.D. Roberts, Prog. Part. Nucl. Phys. 61 (2008) 50
Dyson-Schwinger
Pion’s valence-quark
Distribution Amplitude
Dilation of pion’s wave
function is measurable in
pion’s electromagnetic form
factor at JLab12
A-rated: E12-06-10
 Established an one-to-one connection between DCSB and the pointwise form of the pion’s
wave function.
 Dilation measures the rate at which dressed-quark approaches the asymptotic bare-parton
limit
 Experiments at JLab12 can empirically verify the behaviour of M(p), and hence chart the IR
limit of QCD
Craig Roberts: Mapping Parton Structure and Correlations (62p)
Hall-A Collaboration Meeting: 13-14 June 2013
62
Pion distribution amplitude from lattice-QCD,
I.C. Cloët et al. arXiv:1306.2645 [nucl-th]
Lattice comparison
Pion’s valence-quark PDA
 Employ the generalised-Gegenbauer method described previously (and in
Phys. Rev. Lett. 110 (2013) 132001 (2013) [5 pages]).
 Lattice-QCD V. Braun et al., PRD 74 (2006) 074501
=> one nontrivial moment:
<(2x-1)2> = 0.27 ± 0.04
 Legend
•
•
•
•
Solid = DB (Best) DSE
Dashed = RL DSE
Dotted (black) = 6 x (1-x)
Dot-dashed = midpoint lattice;
and the yellow shading exhibits
band allowed by lattice errors
DB α=0.31 but 10% a2<0
RL α=0.29 and 0% a2
φπ~ xα (1-x)α
= 0.67
α=0.35 +0.32
- 0.24 = 0.11
Craig Roberts: Mapping Parton Structure and Correlations (62p)
Hall-A Collaboration Meeting: 13-14 June 2013
63
Physics Programs at EIC@HIAF
Opportunity to bring Chinese hadron physics to the forefront in the world
•
•
•
•
•
•
Nucleon spin-flavor structure (polarized sea, Ds)
3-d Structure: GPDs (Deep-Virtual Meson Production, pion/Kaon)
Unique opportunity for TMD in “sea quark” region
and significant increase in Q2 / PT range for valence region
Pion/Kaon structure functions
e-A to study hadronization
EMC-SRC in e-A
……
2nd Conference on QCD and Hadron Physics:
http://qcd2013.csp.escience.cn/dct/page/1
Whitepaper on EIC@China is being worked on
Other Physics Programs
E-A programs (not covered):
Hadronization, EMC-SRC
Other e-N programs:
Nucleon Form Factors
Hadron Spectroscopy
Parity Violating e-N
Form Factor Measurements at EIC@HIAF?
• Fast Falling of Form Factors and Elastic Cross Sections
Needs very high luminosity
• Luminosity comparison:
JLab: >1038 unpolarized, >1036 polarized
EIC@HIAF: 1033.
• Limited role for EIC@HIAF in nucleon form factor study
Hadron Spectroscopy Measurements with an EIC?
• e+e- (Bella, BaBar, BES): charmonium states: x-y-z
search for new states
.
• JLab12: GlueX search for gluon excitation
Search for new hadron states
• No obvious advantage, probably limited role for EIC,
including EIC@HIAF
68
PV e-p: Completed, planned (JLab12),
and possible ELIC/ERHIC measurements
 EIC allows to probe the electro-weak
mixing angle over a wide range of Q
Parity Violating e-N at EIC@HIAF?
• Need high precision
asymmetry increase with energy
JLab12 with L~ 5x1038
ELIC/E-RHIC 50x200 with L ~ 1035
EIC@HIAF 3x12 with L ~ 1033: not enough precision?
Summary
• Nucleon Structure Study: Discoveries and Surprises
Understand strong interaction/nucleon structure: remains a challenge
• JLab facility/12 GeV upgrade
• (Planned) EIC facilities
• Examples of “Golden Experiments”
Nucleon spin-flavor structure (polarizd sea, Ds)
3-d Structure: GPDs (DVMP) and DVCS
3-d Structure: TMDs (sea, range in Q2, PT)
Form factors/Spectroscopy/Parity violation e-N
• EIC@HIAF opens up a new window to study/understand nucleon
structure, especially the sea
Will be at the forefront in the world hadron physics for one decade
Exciting new opportunities  lead to breakthroughs?