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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Nuclear Physics at Jefferson Lab
Part III
R. D. McKeown
Jefferson Lab
College of William and Mary
Taiwan Summer School
June 30, 2011
Exotic
like
Flux tube excitation (and parallel quark spins) lead to exotic JPC
Excited Flux Tube
Quarks
Hybrid Meson
like
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.
BNL 852 (18 GeVp)
(ARRA)
Lattice
Hall D
RHIC p + p data
gluon polarization
Global Fit
Well maybe not….
D. de Florian et al., PRL 101 (2008) 072001
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
Beyond form factors and quark distributions –
Generalized Parton Distributions (GPDs)
R. D. McKeown June 15, 2010
X. Ji, D. Mueller, A. Radyushkin (19941997)
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)
]
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
Deeply Virtual Compton Scattering (DVCS)
hard vertices
g
x – longitudinal quark
momentum fraction
x+x
xx
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.
Ds
2s
s+  s
s+ + s
A =
=
Cleanest process: Deeply Virtual Compton Scattering
ξ=xB/(2xB)
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
Elastic form
factors
Real Compton
scattering at high t
Parton momentum
distributions
GPDs
Deeply Virtual Meson production
Deeply Virtual
Compton Scattering
Single Spin
Asymmetries
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
CLAS12
sinφ moment of ALU
Experimental DVCS program E1206119 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
Separate Sivers and Collins effects
Sivers angle, effect in distribution function:
(fhfs) = angle of hadron relative to initial quark spin
Collins angle, effect in fragmentation function:
(fh+fs) = p+(fhfs’) = angle of hadron relative to final quark spin
SIDIS Electroproduction of Pionsq
target angle
hadron angle
Scattering Plane
ee’ plane
f1 =
Unpolarized
BoerMulder
h1=
h1L=
Transversity
h1T =
Polarized
Target
Sivers
f1T=
Pretzelosity
h1T=
Polarized
Beam and
Target
g1 =
g1T=
SL, ST: Target Polarization; le: Beam Polarization
Nucleon Spin
Quark Spin
Leading Twist
h1=
f1 =
BoerMulder
g1 =
h1L=
Helicity
h1T =
f1T=
Transversity
g1T=
h1T=
Sivers
Pretzelosity
SIDIS SSAs depend on 4 variables (x, Q2, z and PT )
Large angular coverage and precision measurement of asymmetries in 4D phase space are essential.
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 DataNSAC 2007 LongRange Plan:
“An ElectronIon 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.”
mEIC
EIC
12 GeV
4/5 will produce white paper for publication
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!)
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 12 Tm dipole.
TOF
Solenoid yoke + Muon Detector
RICH or DIRC/LTCC
45m
Tracking
RICH
EM Calorimeter
HTCC
Muon Detector
Hadron Calorimeter
EM Calorimeter
Veryforward detector
Large dipole bend @ 20 meter from IP (to correct the 50 mr ion horizontal crossing angle) allows for verysmall angle detection (<0.3o)
Solenoid yoke + Hadronic Calorimeter
2m
3m
2m
beyond the standard model