nilanga liyanage , university of virginia

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