TMDs and PVDIS: JLab 6 GeV results and 12 GeV Plan
J. P. Chen , Jefferson Lab APFB2014, Hahndorf, Australia, April 7-11, 2014
TMDs with 6 GeV JLab: Exploration
Recent and new results with a transversely Polarized 3He (n)
Collins/Sivers/Worm-gear asymmetries on pions and Kaons
Inclusive hadron and electron SSA
JLab 12 GeV Plan for TMD study: Precision Multi-d Mapping
SoLID Program on TMDs
PVDIS with 6 GeV JLab: New Results
12 GeV plan for PVDIS: SoLID Program
JLab 12 GeV Upgrade
Maintain capability to deliver lower pass beam energies : 2.2, 4.4, 6.6,….
Enhanced capabilities in existing HallsIncrease of Luminosity 1035 - ~1039 cm-2s-1
The completion of the 12 GeV Upgrade of CEBAF was ranked the highest priority in the 2007 NSAC Long Range Plan. New Hall
CHL-2
20 cryomodules
Add 5 cryomodules
Add 5 cryomodules
20 cryomodules
Add arc
Wpu(x,k
T,r ) Wigner distributions
d2kT
PDFs f1
u(x), .. h1u(x)
GPDs/IPDs
d2kTd2rT
TMD PDFs
f1u(x,kT), ..
h1u(x,kT) 3D imaging
5D Dist.
Form FactorsGE(Q2), GM(Q2)
d2rT
dx &Fourier Transformation
1D
Unified View of Nucleon Structure
Quark polarization
Unpolarized(U)
Longitudinally Polarized (L)
Transversely Polarized (T)
Nucleon Polarization
U
L
T
Leading-Twist TMD PDFs
f1 =
f 1T =
Sivers
Helicityg1 =
h1 =Transversity
h1 =
Boer-Mulders
h1T =
Pretzelosity
g1T =
Worm Gear
h1L =
Worm Gear
: Probed with transversely pol targetHERMES, COMPASS, JLab E06-010
Nucleon Spin
Quark Spin
Scattering Plane
Gold mine for TMDs Access all eight leading-twist TMDs
through spin-comb. & azimuthal-modulations
Tagging quark flavor/kinematics
Tool: Semi-inclusive DIS (SIDIS)
Status of Transverse Spin/TMD Study • Large single spin asymmetry in pp->pX (Fermi, RHIC-spin)
• Collins Asymmetries - sizable for the proton (HERMES and COMPASS) large at high x, p- and +p has opposite sign unfavored Collins fragmentation as large as favored (opposite sign)? - consistent with 0 for the deuteron (COMPASS)• Sivers Asymmetries - non-zero for p+ from proton (HERMES), new COMPASS data - large for K+ ?
• Collins Fragmentation from Belle• Global Fits/models: Anselmino et al., Yuan et al., Pasquini et al., Ma et al., …• Very active theoretical and experimental efforts
JLab (6 GeV and 12 GeV), RHIC-spin, Belle, FAIR, J-PARC, EIC, …• First neutron measurement from Hall A 6 GeV (E06-010)• SoLID with polarized p and n(3He) at JLab 12 GeV Unprecedented precision with high luminosity and large acceptance
Single Spin Asymmetries with A Transversely Polarized 3He (n)
JLab Hall A E06-010Published and Preliminary Results
From SIDIS and Inclusive Reactions
SIDIS: Separation of Collins, Sivers and pretzelocity effects through angular dependence
1( , )
sin( ) sin( )
sin(3 )
l lUT h S
h SSiverCollins
Pretzelosi
UT
tyU
sUT h S
h ST
N NA
P N
A
A
N
A
1
1 1
1
1 1
sin( )
sin(3 )
sin( )Co
PretzelosityU
SiversUT
llins
T h S T
h S
UT
UT h S
TU
UT
TA
H
f
A
D
A h H
h
E06 010 Experiment‑
• First measurement on n (3He)• Transversely Polarized 3He Target• Polarized Electron Beam, 5.9 GeV
• BigBite at 30º as Electron Arm– Pe = 0.7 ~ 2.2 GeV/c
• HRSL at 16º as Hadron Arm– Ph = 2.35 GeV/c – Excellent PID for p/K/p
9
Beam Polarimetry(Møller + Compton)
LuminosityMonitor
XKeeHe ),(3 Spokespersons: J. P. Chen, E. Cisbani, H. Gao, X. Jiang and J. C. Peng 7 PhD Thesis Students (graduated) + 2 new students
3He (n) Target Single-Spin Asymmetry in SIDIS
,),',(n hhee
neutron Sivers SSA:negative for π+, Agree with Torino Fit
neutron Collins SSA small Non-zero at highest x for p+
Blue band: model (fitting) uncertainties Red band: other systematic uncertainties
E06-010 collaboration, X. Qian at al., PRL 107:072003(2011)
Asymmetry ALT Result
• neutron ALT : Positive for p- • Consist w/ model in signs, suggest larger asymmetry
hq
qTLT DgFA shsh
11)cos()cos(
LT
To leading twist:
J. Huang et al., PRL. 108, 052001 (2012).
Worm-Gear
Dominated by L=0 (S) and L=1 (P) interference
Trans helicity
Pretzelosity Results on Neutron
Extracted Pretzelosity Asymmetries,
New Results
In models, directly related to OAM,L=0 and L=2 interference
Analysis by Y. Zhang (Lanzhou) and X. Qian (Caltech)
submitted to PRC, arXiv:1312.3047
E06-010: Inclusive Hadron SSA (AN)
• Clear non-zero vertical target SSA
• Opposite sign for p+ and p-
• Large for K+
0 hN PxlS
0sin90=A S
SUT
vertical target
ShNUT PxlSσ sin∼
Analysis by K, Allada (JLab), Y. Zhao (USTC),
PRC 89, 042201 (2014)
E06-010: Inclusive Hadron SSA (AN)
• Clear non-zero target SSA
• Opposite sign for p+ and p-
• AN at low p
T not very well
understood• Results consistent with
predictions based on Sivers mechanism (valid at high pT )
0 hN PxlS
0sin90=A S
SUT
vertical target
Inclusive Target Single Spin Asymmetry: DIS
3Heθ
e-
• Unpolarized e- beam incident on 3He target polarized normal to the electron scattering plane.
• However, Ay=0 at Born level, sensitive to physics at order α2; two-photon exchange.
Ay (Q2)
• In DIS case: related to integral of Sivers• Physics Importance discussed in A. Metz’s paper
Inclusive Target Single-Spin Asymmetry
Extracted neutron SSA from 3He(e,e’) • Results show 2-photon
effects• Consistent with A.
Metz’s prediction: 2-photon interact with 2 quarks and q-g-q correlator from Torino fit for Sivers (solid black)
• Disagree with predictions based on KQW q-g-q correlator (red-dashed)
• Disagree with predictions based on 2-photon interact with 1 quark (blue dashed)
Analysis by J. Katech(W&M), X. Qian (Caltech), submitted to PRL, arXiv:1311.0197
JLab 12 GeV Era: Precision Study of TMDs
• From exploration to precision study with 12 GeV JLab• Transversity: fundamental PDFs, tensor charge• TMDs: 3-d momentum structure of the nucleon• Quark orbital angular momentum• Multi-dimensional mapping of TMDs
• 4-d (x,z,P┴,Q2)
• Multi-facilities, global effort
• Precision high statistics• high luminosity and large acceptance
SoLID for SIDIS/PVDIS with 12 GeV JLab
•Exciting physics program: Five approved experiments: three SIDIS “A rated”, one PVDIS “A rated”, one J/Psi “A- rated”
•International collaboration: nine countries and 50+ institutions
•GEMs for tracking •Cherenkov and EM
Calorimeter for electron PID •Heavy Gas Cherenkov and
MRPC (TOF) for pion PID
•CLEOII Magnet (official)•pCDR just completed
Mapping of Collins(Sivers) Asymmetries with SoLID E12-10-006 (n) Spokespersons: J. P. Chen, H. Gao, X. Jiang, J. C. Peng and X. Qian
E12-11-108(p): K. Allada, J. P. Chen, H. Gao, X. Li and Z. E. Meziani Both Approved with “A” Rating
• Both p+ and p-• Precision Map in
region
x(0.05-0.65) z(0.3-0.7)
Q2(1-8)
PT(0-1.6)
• <10% d quark tensor charge
Collins (Sivers) Asymmetries
Expected Improvement: Sivers Function
• Significant Improvement in the valence quark (high-x) region• Illustrated in a model fit (from A. Prokudin)
f 1T =
E12-11-107: Worm-gear functions (A rating )Spokespersons: J. P. Chen, J. Huang, Y. Qiang and W. Yan
• Dominated by real part of interference between L=0 (S) and L=1 (P) states
• No GPD correspondence• Lattice QCD -> Dipole Shift in mom. space.• Model Calculations -> h1L
=? -g1T .
h1L =
g1T =
Longi-transversityTrans-helicity
Cent
er o
f poi
nts:
)()(~ 11 zDxgA TLT )()(~ 11 zHxhA LUL
Access transversity in transversely polarized neutron target through π+ π- di-hadron production
Run simultaneously with SIDIS 3He (e,e’π±)X
Systematical check of two approaches to access h1
New : LOI – Dihadron in DIS on 3HeSpokespersons: J. P. Chen, A. Courtoy, H. Gao and J. Zhang
Asymmetry projection for one M-z bin
Summary on TMD Program• Unprecedented precision 4-d mapping of SSA
• Collins, Sivers, Pretzelosity and Worm-Gear• Both polarized 3He (n) and polarized proton with SoLID• Three “A” rated experiments approved. One LOI on di-hadron.• Combining with the world data
• extract transversity and fragmentation functions for both u and d quarks• determine tensor charge• study TMDs for both valence and sea quarks • learn quark orbital motion and quark orbital angular momentum• study Q2 evolution
• Global efforts (experimentalists and theorists), global analysis• much better understanding of multi-d nucleon structure and QCD
• Welcome new collaborators
• Longer-term future: Electron-Ion Collider to study sea and gluon TMD EIC in China (a new possibility)
World Knowledge on Electron-Quark Contact Interaction Terms
Note the equal scale in horizontal and vertical direction. Yet data on C2q won't fit inside the frame.
PVDIS at 6 GeV (JLab E08-011)Ran in Oct-Dec 2009, 100uA, 90% polarized electron beam, 20-cm liquid deuterium target
Scaler-based fast counting DAQ specifically built for the 500kHz DIS rates w/ 104 pion rejection.
Spokespeople: P. Reimer, R. Michaels, X.Z.
Postdoc: Ramesh Subedi
Grad. Students: Kai Pan (MIT), Xiaoyan Deng (UVa),
PhD Students: Diancheng Wang (UVa),
With JLab E08-011 Results
Improved on C2q by factor of five
Agree with Standard Model
2C2u-C2d is two sigma from zero, as predicted by the Standard Model.
PVDIS with SoLIDContact Person: P. Souder
• High Luminosity on LD2 and LH2 • Better than 1% errors for small bins
over large range kinematics• Test of Standard Model • Quark structure:
charge symmetry violation
quark-gluon correlations
d/u at large-x
QCD: Charge Symmetry Violation
We already know CSV exists:• u-d mass difference δm = md-mu ≈ 4 MeV
δM = Mn-Mp ≈ 1.3 MeV• electromagnetic effects
• Direct observation of CSV—very exciting!• Important implications for PDF’s• Could be a partial explanation of the NuTeV anomaly
For APV in electron-2H DIS:
Broad χ2 minimum
(90% CL)
MRST PDF global with fit of CSVMartin, Roberts, Stirling, Thorne Eur Phys J C35,
325 (04)
MRST (2004)
SoLID-J/y: Study Non-Perturbative Gluons
Quark Energy
Trace Anomaly
Gluon Energy
Quark Mass
50 days @ 1037 N/cm2/s
* /N N J
J/ψ: ideal probe of non-perturbative gluon
The high luminosity & large acceptance capability of SoLID enables a unique “precision” measurement near threshold
• Search for threshold enhancement• Shed light on the conformal anomaly
G G
X. Ji PRL 74 1071 (1995)
Spokespersons: K. Hafidi, Z.E. Meziani, X. Qian, N. Sparveris and Z. Zhao
Summary
• Nucleon TMD study have been exciting and fruitful• Recent and Preliminary Results on TMD studies from JLab• JLab 12 GeV : Planned SoLID program on TMDs
Precision 4-d mapping of TMD asymmetriesPrecision experimental data + development in theory for Nucleon TMDs +… lead to breakthrough in understanding QCD?
• Results from 6 GeV PVDIS• JLab 12 GeV: Solid Program on PVDIS Low energy test of Standard Model
Precision Hadron Structure Study: Charge Symmetry Violation,
Higher-twist effect, d/u at high x
Jefferson Lab at a Glance (12 GeV now! )
~ 1400 Active Users ~ 800 FTEs 178 Completed Experiments
@ 6 GeV Produces ~1/3 of US PhDs
in Nuclear Physics A B C
CEBAF High-intensity electron
accelerator based on CW SRF technology
Emax = 6 GeV Imax = 200 mA Polmax = 85%
A B C
12 GeV
Flavor PT Dependence from Theory
Chiral quark-soliton model (Schweitzer, Strikman, Weiss, JHEP, 1301 (2013)
sea wider tail than valance
• Flagmentation model, Matevosyan, Bentz, Cloet, Thomas, PRD85 (2012) unfavored pion and Kaon wider than favored pion
f1u/f1d
kT
A1 PT-dependence
CLAS data suggests that width of g1 is less than the width of f1
Lattice
PT
arXiv:1003.4549 A
1
B.Musch et al arXiv:1011.1213
plots courtesy of Harut Avagyan
E06-010 3He Target Single-Spin Asymmetry in SIDIS
3He Sivers SSA:negative for π+,
3He Collins SSA small Non-zero at highest x for p+
Blue band: model (fitting) uncertainties Red band: other systematic uncertainties
X. Qian at al., PRL 107:072003(2011)
Asymmetry ALT Result
• 3He ALT : Positive for p-
hq
qTLT DgFA shsh
11)cos()cos(
LT
To leading twist:
J. Huang et al., PRL. 108, 052001 (2012).
Worm-Gear.
Inclusive Hadron Electroproduction
e + N↑ h + X (h = p, K, p)
Why a non-zero AN
is interesting?
– Analogues to AN in collision
– Simpler than due to only one quark channel – Same transverse spin effects as SIDIS and p-p collisions (Sivers, Collins, twist-3)– Clean test TMD formalism (at large p
T ~ 1 GeV or more)
– To help understand mechanism behind large AN in in the TMD framework
pT
pp↑→hX
Ssin
UTTFN A=p,xA
pp↑→ hX
pp↑→ hX
ShNUT PxlSσ sin∼
Transverse SSA in Inclusive Hadron
• Target spin flip every 20 minutes• Acceptance effects cancels • Overall systematic check with A
N at ϕ
S= 0
– False asymmetry < 0.1%
0sin
=A SS
UT
N+N
NN=A S
UT
sinp+ p-
False Asymmetry
0=PxlS hN
JLab Physics Program at 12 GeV
49
Hall C – precision determination of valence quark properties in nucleons and nuclei
high momentum spectrometers & dedicated equipments
Hall B - 3-D nucleon structure via GPDs & TMDs Search new form of hadron. matter via Meson Spectr.
4p detector
Hall A – form factors, GPDs & TMDs , SRCLow-energy tests of the SM and Fund. Symmetry Exp
SoLID, MOLLER.
High luminosity, high resolution & dedicated equipments
Hall D - exploring origin of confinement by studying exotic mesons using real photons
Hermetic detectorPhoton tagger
Hall A
Hall B
Hall C
Hall D
H2 D2
Hall C/SHMSL-T studies, precise p+/p- ratios
Hall C/SHMSL-T studies, precise p+/p- ratios
3He, NH3
Hall A/SBSHigh x - Q2, 2-3D
Hall A/SBSHigh x - Q2, 2-3D
Hall A/SOLIDHigh Lumi and acceptance – 4D
Hall A/SOLIDHigh Lumi and acceptance – 4D
U L TqN
U
L
T H2/D2,NH3/ND3, HD
Hall B/CLAS12General survey, medium luminosity
Hall B/CLAS12General survey, medium luminosity
Multi-Halls SIDIS Program
Green (Blue) Points: SoLID projections for polarized NH3 (3He/n) targetLuminosity: 1035 (1036) (1/cm2/s); Time: 120 (90) days
Black points: EIC@HIAF projections for 3 GeV e and 12 GeV pLuminosity: 4 x 1032 /cm2/s; Time: 200 days
The TMD simulation: Projections for SIDIS Asymmetry π+
Haiyan Gao (Duke)
EIC@HIAF reach high precision similar to SoLID at lower x, higher Q2 region
QCD: Higher Twist
From the Quark Parton Model (QPM) to QCD1.Add DGLAP evolution2.Add higher order terms in the Operator Product Expansion (OPE)↔Higher Twist Terms
Parton Model—leading twist
Di-quarks
Quark-gluondiagram
What is a truequark-gluonoperator?
Quark-gluon operatorscorrespond to
transverse momentum
QCD equationsof motion