The 12 GeV Upgrade of The 12 GeV Upgrade of Jefferson LabJefferson Lab

Volker BurkertVolker Burkert

Jefferson LabJefferson Lab

Highlights of the 12 GeV Science Highlights of the 12 GeV Science ProgramProgram

New and revolutionary access to the New and revolutionary access to the structure of the proton and neutron (GPDs, structure of the proton and neutron (GPDs, TMDs)TMDs)

Unlocking the secrets of QCD: confinement Unlocking the secrets of QCD: confinement and space-time dynamicsand space-time dynamics

Exploring the quark structure of nucleiExploring the quark structure of nuclei

Precision tests of the Standard ModelPrecision tests of the Standard Model

JLab Upgrade to 12 GeV

CHL-2CHL-2

Enhance equipment in existing halls

Add new Add new hallhall

New Capabilities in Halls A, B, & C, and a New Hall DNew Capabilities in Halls A, B, & C, and a New Hall D

9 GeV tagged polarized photons and a 4 hermetic detector

D

Super High Momentum Spectrometer (SHMS) at high luminosity and forward angles

C

High Resolution Spectrometer (HRS) Pair, and specialized large installation experiments

A

CLAS12 with new detectors and higher luminosity (1035 /cm2-s)

B

New and revolutionary access to the New and revolutionary access to the structure of the proton and neutronstructure of the proton and neutron

CLAS12CLAS12

2m

Forward Detector

Central Detector

Lum > 1035cm-2s-1

• GPDs & TMDs• Nucleon Spin Structure • N* Form Factors• Baryon Spectroscopy • Hadron Formation

Generalized Parton Distributions and 3D Quark Imaging

Proton form factors, transverse charge & current densities

Last 50 years

Structure functions,quark longitudinalmomentum & spin distributions

Last 40 years

?

Correlated quark momentum and helicity distributions in transverse space - GPDs

Last 10 years

x

Deeply Virtual Compton Scattering (DVCS)

– longitudinal momentum transfer

x – longitudinal quark momentum fraction

–t – Fourier conjugateto transverse impact parameter

Basic Process – Handbag Mechanism

xB

2-xB

=

GPDs depend on 3 variables, e.g. H(x, , t). They probe the quark structure at the amplitude level.

What is the physical content of GPDs?

t

x+

x-

hard vertices

Physical content of GPDsPhysical content of GPDs

M2(t) : Mass distribution inside the nucleon J (t) : Angular momentum distribution d1(t) : Forces and pressure distribution

Nucleon matrix element of the Energy-Momentum Tensor contains three form factors:

GPDs are related to these form factors through moments

Kinematics of deeply virtual exclusive processes

H1, ZEUS

JLab Upgrade

H1, ZEUS

JLab @ 12 G

eV

27 G

eV

200

GeV

W =

2 G

eV

0.7

HERMES C

OMPASS

Study of high xB domain requires high luminosity

The path towards the extraction of GPDs

Selected Kinematics

LU~sin{F1H+.}d

e p ep

Kinematically suppressed

A =

=

Extract H(ξ,t)

Projected results

Spatial Image

Projected precision in extraction of GPD H at x = ξ

Exclusive production on transverse target

2 (Im(AB*)) T UT

A ~ 2Hu + Hd

B ~ 2Eu + Ed0

Q2=5 GeV2

Eu, Ed measure the contributions of the quark orbital angular momentum to the nucleon spin.

0

B

Should be knownfrom DVCS

Separate with ρ+

dX(x,b )

T

Ed(x,t)

M. Burkardt

Tomographic Images of the Proton

Eu(x,t)

uX(x,b )T

CAT scan sliceof human abdomen

flavor polarization

∫d2t

(2)2 e-i·t·b E(x,0,t)Tq(x,b ) =T

Target polarization

The guts of the proton?

Valence structure function flavor Valence structure function flavor dependencedependence

Hall B 11 GeV with CLAS12

Valence structure function spin Valence structure function spin dependencedependence

Proton Deuteron & He-3W > 2; Q2 > 1

Improvements in Improvements in ΔΔu, u, ΔΔd, d, ΔΔG, G, ΔΔss

Important complement to RHIC Spin Important complement to RHIC Spin datadata

Proton electric form factorProton electric form factor

Neutron Magnetic Form Neutron Magnetic Form

FactorFactor At 12 GeV extend knowledge of magnetic structure of neutron to much shorter distances. Needed for constraints of GPDs at large t; related to moments of GPDs: F1(t)= ∫H(t,x,ξ)dx, F2(t)= ∫H(t,x,ξ)dx

Projections for N* Transition Projections for N* Transition Amplitudes @ 12 GeVAmplitudes @ 12 GeV

Probe the transition from effective degrees of freedom, e.g. constituent quarks, to elementary quarks, with characteristic Q2 dependence.

CLAS published

CLAS preliminary

CLAS12 projected

Hybrid mesonsHybrid mesonsFlux Tube ModelFlux Tube Model

• Provides a framework to understand gluonic Provides a framework to understand gluonic excitations.excitations.

• Conventional mesonsConventional mesons have the color flux have the color flux tube in the ground state. When the flux tube tube in the ground state. When the flux tube is excited is excited hybrid mesonshybrid mesons emerge. For static emerge. For static quarks the excitation level above the ground quarks the excitation level above the ground state is ~1 GeV.state is ~1 GeV.

• The excitation of the flux tube, when The excitation of the flux tube, when combined with the quarks, can lead to spin-combined with the quarks, can lead to spin-parity quantum numbers that cannot be parity quantum numbers that cannot be obtained in the quark modelobtained in the quark model (J(JPC - PC - exotics).exotics).

• The decay of hybrid mesons leads to The decay of hybrid mesons leads to complex final states.complex final states.

1GeVqqGqq

JPC = 0+-, 1-+, 2+-

LQCD supports the idea of flux LQCD supports the idea of flux tubes.tubes.

Flux distribution between static quarks.

Flux tubes lead to a linear confining potential.

Exotic Hybrid Mesons MassesExotic Hybrid Mesons Masses

With 3 light quarks the conventional and hybrid mesons form flavor nonets for each JPC.

Photons may be more suited to excite Photons may be more suited to excite exoticsexotics

• In the flux tube model, using photon beams, the production rate of hybrid mesons is not suppressed compared to conventional mesons. N. Isgur, PRD (1999); A. Afanasev & A. Szczepaniak, PRD (2000); F. Close & J. Dudek (2004)

GlueX GlueX – Exotic meson program at – Exotic meson program at 12GeV12GeV

To meet these goals GlueX will:

Quark Propagation and Hadron Formation:Quark Propagation and Hadron Formation:QCD Confinement in Forming SystemsQCD Confinement in Forming Systems

How long can a light quark remain deconfined? How long can a light quark remain deconfined? • The The production time tproduction time tpp measures this measures this

• Deconfined quarks emit gluonsDeconfined quarks emit gluons

• Measure tMeasure tpp via medium-stimulated gluon emission via medium-stimulated gluon emission

How long does it take to form the color field of How long does it take to form the color field of a hadron?a hadron?• The The formation time tformation time tff

hh measures this measures this

• Hadrons interact strongly with nuclear mediumHadrons interact strongly with nuclear medium

• Measure tMeasure tffh h via hadron attenuation in nuclei via hadron attenuation in nuclei

CLAS12

Expected data – Hadronic multiplicity Expected data – Hadronic multiplicity ratioratio

Color transparency in Color transparency in ρρ electroproduction electroproduction

ColorColor TransparencyTransparency is a spectacular is a spectacular prediction of QCD: under the right prediction of QCD: under the right conditions, nuclear matter will allow the conditions, nuclear matter will allow the transmission of hadrons with reduced transmission of hadrons with reduced attenuationattenuation

Totally unexpected in an hadronic picture of Totally unexpected in an hadronic picture of strongly interacting matter, but strongly interacting matter, but straightforward in quark gluon basisstraightforward in quark gluon basis

Why Why ρρ? ? Should be evident first in mesonsShould be evident first in mesons

The signature of CT is the rising of the nuclear transparency The signature of CT is the rising of the nuclear transparency TA with increasing hardness of the reaction (Q)TA with increasing hardness of the reaction (Q)

Measurement at fixed Measurement at fixed coherence length coherence length needed for needed for unambiguous unambiguous interpretationinterpretation)(

222 QMV

c

Predicted results Predicted results high-precision, will high-precision, will permit systematic permit systematic studiesstudies

CLAS preliminary

56Fe

Color transparency in Color transparency in ρρ electroproduction electroproduction

CLAS12 projected

Precision Tests of the Standard Precision Tests of the Standard ModelModel

Electron-Quark PhenomenologyElectron-Quark Phenomenology

C1u and C1d will be determined to high precision by APV and Qweak

C2u and C2d are small and poorly known: can be accessed in PV DIS

New physics such as compositeness, new gauge bosons:

Deviations in C2u and C2d might be fractionally large

A

V

V

A

Proposed JLab upgrade experiment will improve knowledge of 2C2u-C2d by more than a factor of 20

C1i2gA

e gVi

C2i2gV

e gAi

Parity Violating Electron DISParity Violating Electron DIS

e-

N X

e-

Z* *

Must measure APV to fractional accuracy better than 1%

• 11 GeV at high luminosity makes very high precision feasible• JLab is uniquely capable of providing beam of extraordinary stability• Control of systematics being developed at 6 GeV

APV GFQ2

2a(x) f (y)b(x)

a(x) 3

10(2C1u C1d )

b(x) 3

10(2C2u C2d )

uv (x) dv (x)

u(x) d(x)

For an isoscalar target like 2H, one can write in good approximation:

provided Q2 and W2 are high enough and x ~ 0.3

22H Experiment at 11 GeVH Experiment at 11 GeVE’: 6.8 GeV ± 10% lab = 12.5o APV = 290 ppm

Ibeam = 90 µA 800 hours

(APV)=1.0 ppm

60 cm LD2 target

1 MHz DIS rate, π/e ~ 1 HMS+SHMS

xBj ~ 0.45Q2 ~ 3.5 GeV2

W2 ~ 5.23 GeV2

(2C2u-C2d)=0.01

PDG: -0.08 ± 0.24

Theory: +0.0986

ConclusionsConclusions The JLab Upgrade has well defined physics goals of fundamental The JLab Upgrade has well defined physics goals of fundamental

importance for the future of hadron physics, addressing in new importance for the future of hadron physics, addressing in new and revolutionary ways the quark and gluon structure of mesons, and revolutionary ways the quark and gluon structure of mesons, nucleons, and nuclei bynucleons, and nuclei by

• accessing generalized parton distributionsaccessing generalized parton distributions

• exploring the valence quark structure of nucleons exploring the valence quark structure of nucleons

• understanding quark confinement and hadronization processes understanding quark confinement and hadronization processes

• extending nucleon elastic and transition form factors to short distancesextending nucleon elastic and transition form factors to short distances

• mapping the spectrum of gluonic excitations of mesonsmapping the spectrum of gluonic excitations of mesons

• searching for physics beyond the standard modelsearching for physics beyond the standard model

Design of accelerator and equipment upgrades are underwayDesign of accelerator and equipment upgrades are underway

Construction scheduled to begin in 2009 Construction scheduled to begin in 2009

Accelerator shutdown scheduled for 2012 Accelerator shutdown scheduled for 2012

2007 NSAC Long Range Plan (4 2007 NSAC Long Range Plan (4 recommendations)recommendations)

We recommend the completion of the 12 GeV Upgrade at We recommend the completion of the 12 GeV Upgrade at Jefferson Lab.Jefferson Lab.

- It will enable - It will enable three-dimensional imaging of the nucleonthree-dimensional imaging of the nucleon, revealing , revealing hidden aspects of its internal dynamics. hidden aspects of its internal dynamics.

- It will complete our understanding of the It will complete our understanding of the transition between the transition between the hadronic and quark/gluon descriptionshadronic and quark/gluon descriptions of nuclei. of nuclei.

- It will test definitively the It will test definitively the existence of exotic hadronsexistence of exotic hadrons, long-, long-predicted by QCD as arising from quark confinement. predicted by QCD as arising from quark confinement.

- It will provide It will provide low-energy probes of physics beyond the Standard low-energy probes of physics beyond the Standard ModelModel complementing anticipated measurements at the highest complementing anticipated measurements at the highest accessible energy scales.accessible energy scales.

Recommendation 1

DOE Generic Project TimelineDOE Generic Project Timeline

We are hereDOE Reviews

A first search for exotic meson with A first search for exotic meson with

photonsphotons

a1

a2

2 Gluonic Meson?

1(1600)

0.8 1.2 1.6 2.0

102

Eve

nts

/ 20

MeV

45

35

25

15

5

Clarify evidence for exotic meson states, e.g. at 1600 MeV with high statistics. Prepare for full study with GlueX.

Events from previous CLAS experiment.

Expect 1-2 million 3-pion events,3 orders more than any previously published meson photoproduction results, allowing a partial wave analysis.

Experiment planned to run in 2008.

Physical content of GPDsPhysical content of GPDs

M2(t)

Mass/energy density

J(t)

Angular momentum density

In the Chiral Quark Soliton Model

d1(t)

Pressure density

repulsionattraction

CLAS12 - DVCS/BH Target Asymmetry

e p ep

Longitudinally polarized target

~sinIm{F1H+(F1+F2)H...}d~

E = 11 GeV

L = 2x1035 cm-2s-1

T = 1000 hrsQ2 = 1GeV2

x = 0.05

DVCSDVCS DVMPDVMP

Separating GPDs in Flavor & Spin

hard vertices

DVCS depends on all 4 GPDs

Photons cannot separate u/d quarkcontributions.

M = select H, E, for u/d quarksM = select H, E

Isolate longitudinal photons by decay angular distribution.

CAT scan slice of human abdomenCAT scan slice of human abdomen

liverright kidney

pancreasstomach

gall bladder

Can we do similar imaging in the microscopic world?Tools are being developed to add this new dimension to nuclear research.

z

y

3-D Scotty

x

GPDs & PDFs

Deeply Virtual Exclusive Processes & GPDs

2-D Scottyz

x

1-D Scotty

x

prob

abli

tyCalcium

Water

CarbonDeep Inelastic Scattering & Parton Distribution Functions.

X. Ji and F. Yuan, 2003

3D image obtained by rotation around the z-axis

Charge density distributions for u-quarks

y

z

Tomographic Images of the Proton II

x=0.41.5

0

-1.5

fm

-1.5 1.50 fm

x=0.91

0

-1

fm

-1 fm

x=0.012

0

-2

fm

-2 20 fm

interferencepattern

10