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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)

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slide1
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-
  • PretzelosityAsymmetries on p+/p-
  • Inclusive 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 f 2
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
polarized parton distributions
Polarized Parton Distributions

DSSV, PRL101, 072001 (2008)

slide6

The next Frontier

3-D Structure

Generalized Parton Distributions

Transverse Momentum-Dependent Distributions

slide7

Towards Imaging - Two Approaches

TMDs

GPDs

2+1 D picture in momentum space

2+1 D picture in impact-parameter space

Bacchetta, Conti, Radici

QCDSF collaboration

  • collinear but long. momentum transfer
  • indicator of OAM; access to Ji’s total Jq,g
  • existing factorization proofs
  • DVCS, exclusive vector-meson production
  • intrinsic transverse motion
  • spin-orbit correlations- relate to OAM
  • non-trivial factorization
  • accessible in SIDIS (and Drell-Yan)
transverse spin transversity
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
Leading-Twist TMD PDFs

Nucleon Spin

Quark Spin

h1=

Boer-Mulders

f1 =

h1L=

Worm Gear

Helicity

g1 =

h1=

Transversity

f1T=

g1T=

h1T=

Sivers

Worm Gear

Pretzelosity

: Probed with transversely pol target

HERMES, COMPASS, JLab E06-010

slide11

COMPASS Sivers asymmetry 2010 data

x > 0.032 region - comparison with HERMES results

e06 010 experiment spokespersons chen evaristo gao jiang peng
E06‑010 ExperimentSpokespersons: Chen/Evaristo/Gao/Jiang/Peng

Luminosity

Monitor

  • 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

Beam Polarimetry

(Møller + Compton)

slide13

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 3 he target single spin asymmetry in sidis
E06-010 3He Target Single-Spin Asymmetry in SIDIS

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
Results on Neutron

Collins

asymmetries are not large, except at x=0.34

Sivers

negative

Blue band: model (fitting) uncertainties

Red band: other systematic uncertainties

slide16

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 a lt result
Asymmetry ALT Result
  • 3He ALT : Positive for p-

To leading twist:

neutron a lt extraction
Neutron ALT Extraction
    • 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

Trans-helicity

slide19

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 flight cross checked with rich results
Kaon PID by Coincidence time of flightCross checked with RICH results

K+/π+ ratio: ~5%K-/π- ratio: ~1%

slide22

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)

slide23

Pretzelosityon p+/p-

Pretzelosity Asymmetries, 3He(e,e’)

With a transversely polarized target

For both p+ and p-, consistent with zero within uncertainties.

Preliminary

slide24

Extracted Results on Neutron

Extracted Pretzelosity Asymmetries,

For both p+ and p-, consistent with zero within uncertainties.

Preliminary Results

slide25

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
Inclusive Target Single Spin Asymmetry: DIS

θ

3He

e-

  • Unpolarizede- 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)
slide27

Inclusive Target Single-Spin Asymmetry

Extracted neutron SSA

Vertically polarized target

slide28

Future: TMD study with SoLID at 12 GeVJLab 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 tmd s
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
SoLID for SIDIS/PVDIS with 12 GeVJLab
  • 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
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

expected improvement sivers function
Expected Improvement: Sivers Function

f1T=

  • 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
E12-11-107: Worm-gear functions (“A’ rating: ) Spokespersons: Chen/Huang/Qiang/Yan
  • Dominated by real part ofinterference between L=0 (S) and L=1 (P) states
  • No GPD correspondence
  • Lattice QCD -> Dipole Shift in mom. space.
  • Model Calculations -> h1L =? -g1T.

h1L=

Longi-transversity

Trans-helicity

Center of points:

g1T=

slide35

Future: TMD study with SoLID at 12 GeVJLab 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

Measure Transversity via Dihadron with SoLIDLoIsubmitted 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.

projected statistics error
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
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 hadron

SSA: inclusive electron DIS

SSA: inclusive electron (Quasi)Elastic

  • Planned SoLID program with JLab12

Precision 4-d mapping of TMD asymmetries