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Nuclear Physics at Jefferson Lab Part III. R. D. McKeown Jefferson Lab College of William and Mary. Taiwan Summer School June 30, 2011. Outline. Meson spectroscopy and confinement Nucleon tomography Electron Ion Collider. Quantum Numbers of Hybrid Mesons. Exotic. like.

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slide1

Nuclear Physics at Jefferson Lab

Part III

R. D. McKeown

Jefferson Lab

College of William and Mary

Taiwan Summer School

June 30, 2011

slide2

Outline

  • Meson spectroscopy
  • and confinement
  • Nucleon tomography
  • Electron Ion Collider
quantum numbers of hybrid mesons
Quantum Numbers of Hybrid Mesons

Exotic

like

Flux tube excitation (and parallel quark spins) lead to exotic JPC

Excited Flux Tube

Quarks

Hybrid Meson

like

decay of exotic mesons
Decay of Exotic Mesons

Possible daughters:

L=1:a,b,h,f,…

L=0:,,,,…

The angular momentum in the flux tube stays in one of

the daughter mesons (L=1) and (L=0) meson, e.g:

quark L=1

flux tube L=1

Example: p1→b1p

wp→ (3p)p

or wp→ (pg)p

simple decay modes such as ,, … are suppressed.

previous evidence for 1 exotic
Previous “Evidence” for 1-+ Exotic

BNL 852 (18 GeVp-)

  • Results are sensitive to
  • assumption about background
  • partial waves
  • not robust
  • not supported by COMPASS
graphical processor units for lqcd
Graphical Processor Units for LQCD
  • Crays/BlueGene for Gauge Generation - capability
  • GPUs for physics measurements - capacity

(ARRA)

slide7

+-

2

+-

0

-+

1

Hall D@JLab

Isovector Meson Spectrum

States with Exotic Quantum Numbers

Dudek et al.

slide10

Proton Spin Puzzle

HERMES

[X. Ji, 1997]

DIS → DS 0.25

spinning gluons
Spinning Gluons?

RHIC p + p data

 gluon polarization

Global Fit

Well maybe not….

D. de Florian et al., PRL 101 (2008) 072001

slide12

Proton Spin Puzzle

X

X

[X. Ji, 1997]

  • Consider orbital angular
  • momentum

 Consider transverse momenta

slide13

Unified View of Nucleon Structure

d2kT drz

d3r

TMD PDFs f1u(x,kT), .. h1u(x,kT)‏

GPDs/IPDs

6D Dist.

Wpu(x,kT,r ) Wigner distributions

3D imaging

dx &

Fourier Transformation

d2kT

d2rT

Form Factors

GE(Q2),

GM(Q2)‏

PDFs

f1u(x), .. h1u(x)‏

1D

slide14

Beyond form factors and quark distributions –

Generalized Parton Distributions (GPDs)

R. D. McKeown June 15, 2010

X. Ji, D. Mueller, A. Radyushkin (1994-1997)

Proton form factors, transversecharge & current densities

Structure functions,

quark longitudinal

momentum & helicity

distributions

Correlated quark momentum and helicity distributions in transverse space - GPDs

~

~

4 GPDs: H(x,x,t), E(x,x,t), H(x,x,t), E(x,x,t)

slide15

Form factors (sum rules)

]

x

[

1

DIS at

=t=0

å

ò

x

=

q

dx

H

(

x

,

,

t

)

F1

(

t

)Dirac f.f.

q

=

q

H

(

x

,

0

,

0

)

q

(

x

)

]

[

1

å

ò

x

=

q

dx

E

(

x

,

,

t

)

F2

(

t

)Pauli f.f.

~

=

D

q

(

x

,

0

,

0

)

q

(

x

)

H

q

1

1

~

~

ò

ò

x

=

x

=

q

q

dx

H

(

x

,

,

t

)

G

(

t

)

,

dx

E

(

x

,

,

t

)

G

(

t

)

,

,

A

q

P

q

~

~

-

-

1

1

x

q

q

q

q

H

,

E

,

H

,

E

(

x

,

,

t

)

1

1

1

[

]

ò

=

- J G =

x

+

x

J q

xdx

H

q(

x

,

,

0

)

E

q(

x

,

,

0

)

2

2

-

1

X. Ji, Phy.Rev.Lett.78,610(1997)

Link to DIS and Elastic Form Factors

Angular Momentum Sum Rule

slide16

Deeply Virtual Compton Scattering (DVCS)

hard vertices

g

x – longitudinal quark

momentum fraction

x+x

x-x

2x – longitudinal

momentum transfer

–t – Fourier conjugate

to transverse impact

parameter

t

3 dimensional imaging of the nucleon

GPDs depend on 3 variables, e.g.H(x, x, t).They describe

the internal nucleon dynamics.

extraction of gpd s
Extraction of GPD’s

Ds

2s

s+ - s-

s+ + s-

A =

=

Cleanest process: Deeply Virtual Compton Scattering

ξ=xB/(2-xB)

hard vertices

Polarized beam, unpolarized target:

H(x,t)

~

DsLU~ sinf{F1H+ ξ(F1+F2)H+kF2E}df

t

Unpolarized beam, longitudinal target:

~

H(x,t)

~

DsUL~ sinf{F1H+ξ(F1+F2)(H+ξ/(1+ξ)E)}df

Unpolarized beam, transverse target:

E(x,t)

DsUT~ sinf{k(F2H – F1E)}df

slide18

Universality of GPDs

Elastic form

factors

Real Compton

scattering at high t

Parton momentum

distributions

GPDs

Deeply Virtual Meson production

Deeply Virtual

Compton Scattering

Single Spin

Asymmetries

slide19

Quark Angular Momentum

→ Access to quark

orbital angular

momentum

imaging the nucleon
Imaging the Nucleon

Fourier transform of H in momentum transfer t

x < 0.1

x ~ 0.3

x ~ 0.8

gives transverse spatial distribution of quark (parton) with momentum fraction x

slide21

DVCS beamasymmetryat 12 GeV

CLAS12

sinφ moment of ALU

Experimental DVCS program E12-06-119 was approved for the 12 GeV upgrade using polarized beam and polarized targets.

ep epg

High luminosity and large acceptance allows wide coverage

in Q2 < 8 GeV2, xB< 0.65, and

t< 1.5GeV2

sidis electroproduction of pions

Separate Sivers and Collins effects

Sivers angle, effect in distribution function:

(fh-fs) = angle of hadron relative to initial quark spin

Collins angle, effect in fragmentation function:

(fh+fs) = p+(fh-fs’) = angle of hadron relative to final quark spin

SIDIS Electroproduction of Pions

q

target angle

hadron angle

Scattering Plane

e-e’ plane

access tmds through semi inclusive dis
Access TMDs through Semi-Inclusive DIS

f1 =

Unpolarized

Boer-Mulder

h1=

h1L=

Transversity

h1T =

Polarized

Target

Sivers

f1T=

Pretzelosity

h1T=

Polarized

Beam and

Target

g1 =

g1T=

SL, ST: Target Polarization; le: Beam Polarization

transverse momentum dependent parton distributions tmds
Transverse Momentum Dependent Parton Distributions (TMDs)

Nucleon Spin

Quark Spin

Leading Twist

h1=

f1 =

Boer-Mulder

g1 =

h1L=

Helicity

h1T =

f1T=

Transversity

g1T=

h1T=

Sivers

Pretzelosity

a solenoid spectrometer for sidis
A Solenoid Spectrometer for SIDIS

SIDIS SSAs depend on 4 variables (x, Q2, z and PT )

Large angular coverage and precision measurement of asymmetries in 4-D phase space are essential.

solid transversity projected data

Total 1400 bins in x, Q2, PT and z for 11/8.8 GeV beam.

z ranges from 0.3 ~ 0.7, only one z and Q2 bin of 11/8.8 GeV is shown here. π+ projections are shown, similar to the π- .

SoLIDTransversity Projected Data
electron ion collider
Electron Ion Collider

NSAC 2007 Long-Range Plan:

“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. EIC would provide unique capabilities for the study of QCD well beyond those available at existing facilities worldwide and complementary to those planned for the next generation of accelerators in Europe and Asia.”

  • JLAB Concept
  • Initial configuration (mEIC):
      • 3-11 GeV on 12-60 GeVep/eA collider
      • fully-polarized, longitudinal and transverse
      • luminosity: up to few x 1034 e-nucleons cm-2s-1
      • Upgradable to higher energies (250 GeV protons)
eic physics overview
EIC Physics Overview
  • Hadrons in QCD are relativistic many-body systems, with a fluctuating number of elementary quark/gluon constituents and a very rich structure of the wave function.
  • With an (M)EIC we enter the region where the many-body nature of hadrons, coupling to vacuum excitations, etc., become manifest and the theoretical methods are those of quantum field theory. An EIC aims to study the sea quarks, gluons, and scale (Q2) dependence.
  • With 12 GeV we study mostly the valence quark component, which can be described with methods of nuclear physics (fixed number of particles).

mEIC

EIC

12 GeV

medium energy eic@jlab
Medium Energy EIC@JLab
  • Three compact rings:
  • 3 to 11 GeV electron
  • Up to 12 GeV/c proton (warm)
  • Up to 60 GeV/c proton (cold)
meic detailed layout
MEIC : Detailed Layout

warm ring

cold ring

slide35

JLAB EIC Workshops

  • Nucleon spin and quark-gluon correlations: Transverse spin, quark and gluon orbital motion, semi-inclusive processes (Duke U., March 12-13, 2010 )
  • 3D mapping of the glue and sea quarks in the nucleon(Rutgers U., March 14-15, 2010)
  • 3D tomography of nuclei, quark/gluon propagation and the gluon/sea quark EMC effect (Argonne National Lab, April 7-9, 2010)
  • Electroweak structure of the nucleon and tests of the Standard Model(College of W&M , May 17-18, 2010)
  • EIC Detectors/Instrumentation (JLab, June 04-05, 2010)

4/5 will produce white paper for publication

slide36

General Emergent Theme

Experimental study of multidimensional

distribution functions that map out the

quark/gluon properties of the nucleon, including:

(quark) flavor

spin and orbital angular momentum

longitudinal momentum

transverse momentum and position

High Luminosity over a

range of energies

(Challenge to accelerator physics!)

sidis ssa at eic

11 + 60 GeV

3+20 GeV

SIDIS SSA at EIC

Huang, Qian, et al

Duke workshop

gluon saturation
Gluon Saturation
  • Gluon density should saturate
  • (unitarity)
  • Access at very high E
  • Use large nuclei
meic elic luminosity vs cm energy
MEIC & ELIC: Luminosity Vs. CM Energy

e + p facilities

For 1 km MEIC ring

e + A facilities

full acceptance detector
FullAcceptance Detector

7 meters

detectors

solenoid

ion FFQs

ion dipole w/ detectors

ions

IP

0 mrad

electrons

electron FFQs

50 mrad

2+3 m

2 m

2 m

Central detector

Detect particles with angles below 0.5obeyond ion FFQs and in arcs.

Detect particles with angles down to 0.5obefore ion FFQs.

Need 1-2 Tm dipole.

TOF

Solenoid yoke + Muon Detector

RICH or DIRC/LTCC

4-5m

Tracking

RICH

EM Calorimeter

HTCC

Muon Detector

Hadron Calorimeter

EM Calorimeter

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)

Solenoid yoke + Hadronic Calorimeter

2m

3m

2m

outlook
Outlook
  • The Jefferson Lab electron accelerator is currently a unique world-leading facility for nuclear physics research
  • 12 GeV upgrade ensures another decade of opportunities
  • Growing program addressing physics

beyond the standard model

  • Nucleon Tomography is a major future theme
  • Large future project on the horizon: EIC