New results on Neutron Single Target Spin Asymmetries from
Transversely polarized 3He target at Jlab
Nilanga Liyanage , University of Virginia
 Recent SSA Results from JLab Hall A with a Transversely Polarized 3He (n)
Collins/Sivers Asymmetries on pi+/pi- (published)
Worm-gear II Asymmetries on pi+/pi- (published)
 New Preliminary SSA Results from JLab Hall A with a Transversely polarized 3He (n)
Collins/Sivers Asymmetries in K+/K-
Pretzelosity Asymmetries on p+/pInclusive hadron SSA
Inclusive electron SSA (DIS, QE)
 TMD study at JLab 12 GeV in Hall A:
SoLID Program on SSA/TMDs: 3 Approved Experiments on 3He and p
Acknowledgement: thanks to J.P Chen and Jefferson lab Transversity
collaboration for some slides
Unpolarized Structure Function F2
• Bjorken Scaling
• Scaling Violation
• Gluon radiation –
•
QCD evolution
NLO: Next-to-Leading-Order
• One of the best
experimental tests of
QCD
Parton Distribution Functions (CTEQ6)
JHEP 1001: 109 (2010)
Polarized Structure functions
Polarized Parton Distributions
DSSV, PRL101, 072001 (2008)
The next Frontier
3-D Structure
Generalized Parton Distributions
Transverse Momentum-Dependent Distributions
Towards Imaging - Two Approaches
TMDs
2+1 D picture in momentum space
Bacchetta, Conti, Radici
GPDs
2+1 D picture in impact-parameter space
QCDSF collaboration
• intrinsic transverse motion
• collinear but long. momentum transfer
• spin-orbit correlations- relate to OAM
• indicator of OAM; access to Ji’s total Jq,g
• non-trivial factorization
• existing factorization proofs
• accessible in SIDIS (and Drell-Yan)
• DVCS, exclusive vector-meson production
Transverse Spin: Transversity
• Three twist-2 quark distributions:
• Momentum distributions: q(x,Q2) = q↑(x) + q↓(x)
• Longitudinal spin distributions: Δq(x,Q2) = q↑(x) - q↓(x)
• Transversity distributions: δq(x,Q2) = q┴(x) - q┬(x)
• It takes two chiral-odd objects to measure transversity
• Semi-inclusive DIS
Chiral-odd distributions function (transversity)
Chiral-odd fragmentation function (Collins function)
•
TMDs: (without integrating over PT)
• Distribution functions depends on x, k┴ and Q2 : δq, f1T┴ (x,k┴ ,Q2), …
• Fragmentation functions depends on z, p┴ and Q2 : D, H1(x,p┴ ,Q2)
• Measured asymmetries depends on x, z, P┴ and Q2 : Collins, Sivers, …
(k┴, p┴ and P┴ are related)
Leading-Twist TMD PDFs
Quark polarization
Unpolarized
(U)
Nucleon Polarization
U
f1 =
Boer-Mulders
g1 =
f 1T =
Transversely Polarized
(T)
h1 =
L
T
Longitudinally
Polarized (L)
h1L =
Helicity
Worm Gear
h1 =Transversity
Sivers
g1T =
Worm Gear
h1T =
Pretzelosity
Nucleon Spin
Quark Spin
: Probed with transversely pol target
HERMES, COMPASS, JLab E06-010
Separation of Collins, Sivers and pretzelocity effects
through angular dependence


1
N

N
AUT (hl ,  Sl ) 
P N  N
Collins
Sivers
 AUT
sin(h  S )  AUT
sin(h  S )
ty
 AUPretzelosi
sin(3h  S )
T
Collins
UT
A
Sivers
UT
A
 sin(h  S )
 sin(h  S )
UT
UT
 h1  H

1T
 f
AUPretzelosity
 sin(3h  S )
T
UT

1
 D1
 h1T  H1
COMPASS Sivers asymmetry 2010 data
x > 0.032 region
- comparison with HERMES results
Thomas Jefferson National Accelerator Facility
Operated by the Southeastern Universities Research Association for the U.S. Department of Energy
E06-010 Experiment
Spokespersons: Chen/Evaristo/Gao/Jiang/Peng
First measurement on n (3He)
•
• Polarized 3He Target
• Polarized Electron Beam, 5.9 GeV
3

He (e , eK  ) X

Luminosity
Monitor
• 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
• 7 PhD Thesis Students (All graduated)
+ new students
Beam Polarimetry
(Møller + Compton)
12
Published Results (I) from JLab Hall A E06-010
with a Transversely Polarized 3He (n)
Collins/Sivers Asymmetries on p+/pX. Qian at al., PRL 107:072003(2011)
E06-010
3He
Target Single-Spin Asymmetry in SIDIS
3
He-(e, e'h), h = p +, p 3He
Collins SSA small
Non-zero at highest x for p+
3He
Sivers SSA:
negative for π+,
Blue band: model (fitting) uncertainties
Red band: other systematic uncertainties
Results on Neutron
Collins
asymmetries are not
large, except at x=0.34
Sivers
p + (ud ) negative
Blue band: model (fitting) uncertainties
Red band: other systematic uncertainties
Published Results (II) from JLab Hall A E06-010
with a Transversely Polarized 3He (n)
Worm-Gear II: Trans-helicity on p+/pJ. Huang et al., PRL. 108, 052001 (2012).
Asymmetry ALT Result
To leading twist:
cos(h s )
LT
A
•
3He
cos(h s )
LT
F
ALT : Positive for p-
 g1qT  D1hq
Neutron ALT Extraction
•
– Corrected for proton dilution, fp
– Predicted proton asymmetry contribution < 1.5% (π+), 0.6% (π-)
•
n
ALT
 g1qT  D1hq
Trans-helicity
– Dominated by L=0 (S) and L=1 (P) interference
• Consist w/ model in signs, suggest larger asymmetry
Preliminary New Results (I) from JLab Hall A
E06-010 with a Transversely Polarized 3He (n)
Collins/Sivers Asymmetries on K+/KAnalysis by Y. Zhao (USTC), Y. Wang (UIUC)
Kaon PID by Coincidence time of flight
Cross checked with RICH results
K+/π+ ratio: ~5%
K-/π- ratio: ~1%
Preliminary K+/K- Collins and Sivers Asymmetries on 3He
Preliminary New Results (II) from JLab Hall A
E06-010 with a Transversely Polarized 3He (n)
Pretzelosity on p+/pAnalysis by Y. Zhang (Lanzhou) and X. Qian (Caltech)
Pretzelosity on p+/pPretzelosity Asymmetries, 𝑨𝑼𝑻𝐬𝐢𝐧(𝝋𝒉 − 𝝋𝒔), 𝐢𝐧 3He(e,e’)
With a transversely polarized target
For both p+ and p-, consistent with zero within uncertainties.
Preliminary
Extracted Results on Neutron
Extracted Pretzelosity Asymmetries, 𝑨𝑼𝑻𝐬𝐢𝐧(𝝋𝒉 − 𝝋𝒔), 𝐨𝐧 𝐭𝐡𝐞 𝐧𝐞𝐮𝐭𝐫𝐨𝐧
For both p+ and p-, consistent with zero within uncertainties.
Preliminary Results
Preliminary New Results (III)from JLab Hall A
E06-010 with a polarized 3He (n)
Inclusive Electron SSA
Analysis by J. Katech(W&M), X. Qian (Caltech)
Inclusive Target Single Spin Asymmetry: DIS





Ay (Q 2 )  
  
θ
3He
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.
• In DIS case: related to integral of Sivers
• Physics Importance discussed in A. Metz
and M. Schlegel’s talks (Tuesday)
Inclusive Target Single-Spin Asymmetry
Extracted neutron SSA
Vertically polarized target
Future: TMD study with SoLID at 12 GeV JLab Hall A
Precision 4-D mapping of Collins/Sivers/Pretzelosity
Worm-Gear I/II
with Polarized 3He (Neutron) and Proton
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: eight countries and 50+ institutions
• CLEOII Magnet
• GEMs for tracking
• Cherenkov and EM
Calorimeter for electron PID
• Heavy Gas Cherenkov and
MRPC (TOF) for pion PID
E12-10-006/E12-11-108, Both Approved with “A” Rating
Mapping of Collins(Sivers) Asymmetries with SoLID
• 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 Asymmetry
Map Collins and Sivers asymmetries in 4-D (x, z, Q2, PT)
Expected Improvement: Sivers Function
f 1T =
• Significant Improvement in the valence quark (high-x) region
• Illustrated in a model fit (from A. Prokudin)
E12-11-107: Worm-gear functions (“A’ rating: )
Spokespersons: Chen/Huang/Qiang/Yan
g1T =
Longi-transversity
Trans-helicity
Center of points:
• 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 =
ALT ~ g1T ( x) D1 ( z)
AUL ~ h 1L ( x) H 1 ( z )
Future: TMD study with SoLID at 12 GeV JLab Hall A
New Letter Of Intent: Dihadron Production
Measure Transversity via Dihadron with SoLID
LoI submitted to Jlab PAC 40, J. Zhang, A. Courtoy, et al.
•
•
•
Precision dihadron (p+/p-) production on a transversely polarized 3He (n)
Extract transversity on neutron
Provide crucial inputs for flavor separation of transversity
Wide xb and Q2 coverages
Projected Statistics error for one (Mpp,zpp)
bin, integrated over all y and Q2.
Projected Statistics Error
• Hall A, SoLID program
• Polarized 3He target, (~60%
polarization)
• Lumi=1036 (n)/s/cm2
• Wide xband Q2 coverages
• Bin central values labeld on
axises
• 4-d (xb, Q2, Zp+p-,Mp+p-) mapping
• Z scale (color) represent stat.
error
Summary
• SSA and TMD study have been exciting and fruitful
• Recent and Preliminary Results from JLab Hall A with a transversely
polarized 3He (n) target
Collins/Sivers asymmetries for p+/p-/K+/KPretzelosity on pi+/piSSA: inclusive hadron
SSA: inclusive electron DIS
SSA: inclusive electron (Quasi)Elastic
• Planned SoLID program with JLab12
Precision 4-d mapping of TMD asymmetries