nilanga liyanage , university of virginia
DESCRIPTION
New results on Neutron Single Target Spin Asymmetries from Transversely polarized 3 He target at Jlab. Nilanga Liyanage , University of Virginia. Recent SSA Results from JLab Hall A with a Transversely Polarized 3 He (n) Collins/ Sivers Asymmetries on pi+/pi- (published) - PowerPoint PPT PresentationTRANSCRIPT
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+/p-Inclusive hadron SSAInclusive 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)
3-D Structure
Generalized Parton Distributions
Transverse Momentum-Dependent Distributions
The next Frontier
TMDs2+1 D picture in momentum space
Bacchetta, Conti, Radici
GPDs2+1 D picture in impact-parameter space
QCDSF collaboration
Towards Imaging - Two Approaches
• intrinsic transverse motion• spin-orbit correlations- relate to OAM• non-trivial factorization• accessible in SIDIS (and Drell-Yan)
• collinear but long. momentum transfer
• indicator of OAM; access to Ji’s total Jq,g
• existing factorization proofs
• 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)
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
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 NAP N
A
ANA
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
Operated by the Southeastern Universities Research Association for the U.S. Department of Energy
Thomas Jefferson National Accelerator Facility
COMPASS Sivers asymmetry 2010 datax > 0.032 region - comparison with HERMES results
E06 010 Experiment‑Spokespersons: Chen/Evaristo/Gao/Jiang/Peng
• First measurement on n (3He)• 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
• 7 PhD Thesis Students (All graduated) + new students
12
Beam Polarimetry(Møller + Compton)
LuminosityMonitor
XKeeHe ),(3
Published Results (I) from JLab Hall A E06-010 with a Transversely Polarized 3He (n)
Collins/Sivers Asymmetries on p+/p-
X. Qian at al., PRL 107:072003(2011)
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
Results on Neutron
Collinsasymmetries are not large, except at x=0.34
Sivers 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+/p-
J. Huang et al., PRL. 108, 052001 (2012).
Asymmetry ALT Result
• 3He ALT : Positive for p-
hq
qTLT DgFA shsh
11)cos()cos(
LT
To leading twist:
• – Corrected for proton dilution, fp
– Predicted proton asymmetry contribution < 1.5% (π+), 0.6% (π-)•
– Dominated by L=0 (S) and L=1 (P) interference• Consist w/ model in signs, suggest larger asymmetry
Neutron ALT Extraction
hq
qT
n DgA 11LT Trans-helicity
Preliminary New Results (I) from JLab Hall A E06-010 with a Transversely Polarized 3He (n)
Collins/Sivers Asymmetries on K+/K-Analysis by Y. Zhao (USTC), Y. Wang (UIUC)
Kaon PID by Coincidence time of flightCross 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+/p-Analysis by Y. Zhang (Lanzhou) and X. Qian (Caltech)
Pretzelosity on p+/p-Pretzelosity Asymmetries, 3He(e,e’) With a transversely polarized targetFor both p+ and p-, consistent with zero within uncertainties.
Preliminary
Extracted Results on NeutronExtracted Pretzelosity Asymmetries, 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
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 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/IIwith 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
• 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: Chen/Huang/Qiang/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
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.
Wide xb and Q2 coverages
Projected Statistics error for one (Mpp,zpp) bin, integrated over all y and Q2.
• Precision dihadron (p+/p-) production on a transversely polarized 3He (n) • Extract transversity on neutron• Provide crucial inputs for flavor separation of transversity
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+/K-
Pretzelosity on pi+/pi-SSA: inclusive hadronSSA: inclusive electron DISSSA: inclusive electron (Quasi)Elastic
• Planned SoLID program with JLab12 Precision 4-d mapping of TMD asymmetries