Prospects for GPD and TMD studies at the JLab Upgrade
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Transcript of Prospects for GPD and TMD studies at the JLab Upgrade
Prospects for GPD and TMD studies at the JLab Upgrade
Volker D. Burkert*)
Jefferson Lab
QCDN’06 Workshop, June 12-16, 2006, Rome
Introduction JLab Upgrade and CLAS12 GPDs from DVCS and DVMP TMDs from SIDIS and SSA Summary
*) Talk presented by H.Avakian
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3-D Scotty
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1-D Scotty
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Water
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GPDs, TMDs & PDFs
Deeply Inelastic Scattering,PDFs
This Workshop – GPDs, TMDs
Wpu(x,k,r) “Parent” Wigner distributions
d 2kT(FT)
GPDs: Hpu(x,,t), Ep
u(x,,t),…
GPD
Measure momentum transfer to nucleon.
Probability to find a quark u in a nucleon P with a certain polarization in a position r and momentum k
TMD PDFs: fpu(x,kT),g1,f┴
1T, h┴1L
d3 r
Measure momentum transfer to quark.
TMD
Generalized PDFs (GPDs & TMDs)
•Provide complementary information on structure of nucleon•Studies require detection of multiparticle final states
JLab Upgrade to 12 GeV Energy
CHL-2CHL-2
Enhance equipment in existing halls
Add new Add new hallhall
12 GeV
Beam polarizationPe > 80%
E= 2.2, 4.4, 6.6, 8.8, 11 GeV
CLAS12 EC
TOF
Cerenkov
Torus
Drift Chambers
Cerenkov
Central Detector
BeamlineIEC
Design luminosity = 1035cm-2s-1
Nearly full angle coverage for tracking and ndetection High luminosity, 1035 cm-2s-1
Concurrent measurement of deeply virtual exclusive, semi-inclusive, and inclusive processes.
CLAS12
Beamline
5m
CLAS 12 - Expected Performance Forward Detector Central Detector
Angular coverage: Tracks (inbending) 8o - 40o 40o - 135o
Tracks (outbending) 5o - 40o 40o - 135o Photons 2o - 40o 40o - 135o
Track resolution:p (GeV/c) 0.003p + 0.001p2 pT=0.03pT
(mr) < 1 (>2.5 GeV/c) 8 (1 GeV/c) (mr) < 3 (> 2.5 GeV/c) 2 (1 GeV/c) Photon detection:Energy range > 150 MeV > 60 MeV E/E 0.09(EC)/0.04(IEC) 0.06 (1 GeV)(mr) 4 (1 GeV) 15 (1 GeV)Neutron detection:eff 0.5 (EC), 0.1 (TOF) 0.04 (TOF) Particle id:e/ >>1000 ( < 5 GeV/c) -
>100 ( > 5 GeV/c) -/K (4) < 3 GeV/c (TOF) 0.65 GeV/c
3 - 10 GeV/c (CC)p5 GeV/c (TOF) 1.2 GeV/c
3 - 10 GeV/c (CC)K/p() < 3.5 GeV/c (TOF) 0.9 GeV/c
Deeply Virtual Exclusive Processes - Kinematics Coverage of the 12 GeV Upgrade
H1, ZEUS
JLab Upgrade
11 GeV
H1, ZEUS
JLab @ 12 G
eV11 GeV27
GeV
200
GeV
W =
2 GeV
Study of high xB domain requires high luminosity
0.7
HERMES
COMPASS
DVCSDVCS DVMPDVMP
GPDs – Flavor separation
hard vertices
hard gluon
Photons cannot separate u/d quarkcontributions.
long. only
M = select H, E, for u/d flavorsM = , K select H, E
Q2 > 2.5 GeV2
Forward Detector
Central Detector
ep ep
Acceptance for DVCS, SIDIS
ep e+X
xB = 0.35
EC
IEC
Q2
DVCS/BH- Beam Asymmetry
With large acceptance,measure large Q2, xB, t ranges simultaneously.
A(Q2,xB,t) (Q2,xB,t)
(Q2,xB,t)
Ee = 11 GeV
ALU
CLAS12 - DVCS/BH- Beam Asymmetry
Luminosity = 720fb-1
Ee = 11 GeV
Q2=5.5GeV2
xB = 0.35 -t = 0.25 GeV2
CLAS12 - DVCS/BH Beam Asymmetry
L = 1x1035
T = 2000 hrsQ2 = 1 GeV2
x = 0.05
E = 11 GeV
Selected Kinematics
LU~sinIm{F1H+.}d
e p ep
GPD H from projected DVCS ALU data
bval=bsea=1
MRST02 NNLOdistribution
Q2=3.5 GeV2
Other kinematics measured concurrently
JLab12: Hall A with 3, 4, 5 pass beam
Unphysical
H(e,e’)p Absolute measurements: d(e=±1)250K events/setup
100 days
Twist 2 & Twist 3 separation.
Im{DVCS*BH}+DVCS2
Re{DVCS*BH} +’DVCS2
CLAS12 - DVCS/BH Target Asymmetry
e p ep
Longitudinally polarized target
~sinIm{F1H+(F1+F2)H...}d~
E = 11 GeVL = 2x1035 cm-2s-1
T = 1000 hrsQ2 = 1GeV2
x = 0.05
Provide precision measurements of polarized GPD
CLAS12 - DVCS/BH Target Asymmetry
Asymmetries highly sensitive to the u-quark contributions to the proton spin.
Transverse polarized target
e p ep
~ sinIm{k1(F2H – F1E) +…}d
Q2=2.2 GeV2, xB = 0.25, -t = 0.5GeV2E = 11 GeVSample kinematics
AUTx Target polarization in the scattering plane
AUTy Target polarization perpendicular to the scattering plane
CLAS12 – L/T Separation ep ep
L
T
xB = 0.3-0.4 -t = 0.2-0.3GeV2
Other bins measured concurrently
Projections for 11 GeV(sample kinematics)
Test of Bjorken scaling
Power corrections?
Exclusive production on transverse target
A ~ 2Hu + Hd
B ~ 2Eu + Ed0
K. Goeke, M.V. Polyakov, M. Vanderhaeghen, 2001
Q2=5 GeV2
Eu, Ed probes the orbital
motion of quarks. 0
B
A ~ Hu - Hd
B ~ Eu - Ed+
2 (Im(AB*))/ T
t/4m2) - ReUT
SIDIS at leading twist
e
e
e
p
p
Sivers transversity
Mulders
Boer
Off-diagonal PDFs vanish if quarks only in s-state! In addition T-odd PDFs require FSI (Brodsky et al., Collins, Ji et al. 2002)
Non-perturbative TMD Perturbative region
PT-dependence of beam SSA
In the perturbative limit 1/PT
behavior expected
PT-dependence of azimuthal moments allows studies of transition from non-perturbative to perturbative description (Unified theory by Ji et al).
2.0
EIC
SIDIS Azimuthal Asymmetry - Sivers effect
Probes orbital angular momentum of quarks by measuring the imaginary part of s-p-wave interference in the amplitude. •Hadrons from struck quark have the same sign SSA•Opposite effect in target fragmentation
T(P /M)AUTsin s
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T
CLAS12 - Sivers function from AUT (0)
F1T=∑qeq2f1T
┴qIn large Nc limit:
f1Tu = -f1T
d
Efremov et al(large xB behavior of
f1T from GPD E)
xB xB
CLAS12projected
CLAS12projected
Sivers effect in the target fragmentation
xF<0 (target fragmentation)
xF>0 (current fragmentation)
xF - momentum in the CM frame
Wide kinematic coverage of CLAS12 allows studies of hadronization in the target fragmentation region
Azimuthal Asymmetry - Collins Effect
UT ~ k h1H1
sins)
T
Access to transversity distribution and fragmentation of polarized quarksUnfavored SSA with opposite sign No effect in target fragmentation
Collins Effect and Kotzinian-Mulders Asymmetry
Measures the Collins fragmentation with longitudinally polarized target. Access to the real part of s-p wave interference amplitudes.
UL ~ k h1LH1KM
T T
• June 2006 Annual Review of Project Progress
• August 2006 JLab PAC 30
– First review of 12 GeV proposals – “first 5 years of experiments”
– Key first step in identifying the research interests and significant
contributions of international and other non-DOE collaborators
• October 2006 – start Project Engineering & Design (PED)
• 12 GeV is on track for Construction Approval in Sept 2008
12 GeV Upgrade - Milestones
Summary
The JLab 12 GeV Upgrade is essential for the study of nucleon structure in the valence region with high precision:
- deeply virtual exclusive processes (DVCS, DVMP) - semi-inclusive meson production with polarized beam and polarized targets
Provide new and deeper insight into - quark orbital angular momentum contributions to the nucleon spin- 3D structure of the nucleon’s interior and correlations- quark flavor polarization- …..
CLAS12 will be world wide the only full acceptance, general purpose detector for high luminosity electron scattering experiments, and is essential for the GPD/TMD program.
New Collaborators are welcome!
Additional Slides
CLAS12
CLAS12 – Central Detector
Cryostat vacuum jacket
Main coil
(B0 = 5T)TOF light-guide
Central TOF
SiliconTracker
Space for e.m. calorimeter
Compensation coil
JLab Upgrade - CLAS12
Central Detector
Forward Detector
Luminosity > 1035cm-2s-1
Tracking - Drift Chambers, SVTParticle id - /K/p ToF,
- Cerenkov’s - Calorimetry
Operated by Jefferson Science Associates for the U.S. Department of Energy
• 2004-2005 Conceptual Design (CDR)
• 2004-2008 Research and Development (R&D)
• 2006 Advanced Conceptual Design (ACD)
• 2007-2009 Project Engineering & Design (PED)
• 2008 Long Lead Procurement
• 2008-2012 Construction
• 2012-2013 Pre-Ops (beam commissioning)
12 GeV Upgrade: Project
Critical Decision (CD) CD-1 Documents
CD-0 Mission Need 2QFY04 (Actual)
CD-1 Preliminary Baseline Range 2QFY06(Actual)
CD-2A/3A Construction and Performance Baseline of Long Lead Items
4QFY06/3QFY07
CD-2B Performance Baseline 4QFY07
CD-3B Start of Construction 4QFY08
CD-4 Start of Operations 1QFY14
NOTE – schedule shown per Feb 2006 CD-1 Documents, new funding profile received in April, update of project plan in progress
Critical Decision–1 Approval in February 2006
12 GeV Upgrade included in DOE 5-Year Business Plan in March 2006
Operated by Jefferson Science Associates for the U.S. Department of Energy
Near Term:• June 2006 Annual Review of Project Progress
— Focus on progress in last year, and plans for CD-2B Performance Baseline
review next year
— CD-2B Approval anticipated for September 2007
• August 2006 JLab PAC 30
— First review of 12 GeV proposals – “commissioning experiments”
— Spokespersons make commitments to construction of equipment
— Key first step in identifying the research interests and significant
contributions of international and other non-DOE collaborators
• October 2006 – start Project Engineering & Design (PED)
• 12 GeV is on track for CD-2 in Sept 2007 and CD-3 in Sept 2008
12 GeV Upgrade: Status
Originates in the quark distribution. It is measured in the azimuthal asymmetry with transverse polarized target.
Requires: non-trivial phase from theFSI + interference between different helicity states (S. Brodsky)
Azimuthal Asymmetry – Sivers Effect
f1T D1AUT ~ k sins)
T
Collins Effect and Kotzinian-Mulders Asymmetry
Measures the Collins fragmentation with longitudinally polarized target. Access to the real part of s-p wave interference amplitudes.
UL ~ (1-y) h1LH1KM
T T
`
CLAS12 - (1115) Polarization
ep e(pX (SIDIS)
K*(892)K
E = 11 GeV
polarization in the target fragmentation
p
e
Λ1 2
e’
Link to the Quark Structure of the Nucleon
dxxHq(x,,t) = Hq(t) + 2Dq(t) ∫-1
1
dxxEq(x,,t) = Eq(t) - 2Dq(t) ∫-1
1
Quark distributions in transversespace, and orbital angular momentum distribution.
Distribution of the forces on quarks in transverse space.
finite t