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

z

y

3-D Scotty

x

1-D Scotty

x

prob

abli

tyCalcium

Water

Carbon

2-D Scottyz

x

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

)

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