TMD Study at JLab: Results and Future

J. P. Chen , Jefferson Lab PacificSPIN-13, Jinan, China, October 28-31, 2013

TMDs with 6 GeV JLab: Exploration Results from Hall C: PT dependence of unpolarized flavor PDFs

Results from Hall B (CLAS6)

PT dependence of spin asymmetry A1

SSA with longitudinal target or beam

Recent and preliminary results Hall 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

TMD program in Hall B (CLAS12) and C

Jefferson Lab at a Glance

~ 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

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)

Unpolarized TMDsTest x-z Factorization Flavor PT Dependence

JLab Hall C SIDIS Results

From Form Factors to Transverse Densities

up quark down quarkby

bxbx

by

Unpolarized TMD: Flavor PT Dependence?

A. Bacchetta, Seminar @ Jlab, arXiv1309.3507 (2013)

up quark down quarkky

ky

kxkx

Flavor PT Dependence from Theory

Chiral quark-soliton model (Schweitzer, Strikman, Weiss, JHEP, 1301 (2013)

sea wider tail than valanee

• Flagmentation model, Matevosyan, Bentz, Cloet, Thomas, PRD85 (2012) unfavored pion and Kaon wider than favored pion

f1u/f1d

kT

Hall C Results: Flavor PT Dependence

C

(md)2

(mu)2

(m-)2

(m+)2

Results: from JLab Hall B (CLAS6)

PT Dependence of A1

SSA in Longitudinal TargetSSA in Longitudinal Beam(plots courtesy of Harut Avagyan)

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

Kotzinian-Mulders Asymmetries

KM-TMD unique (no analog in GPDs)

HERMES

CLAS (5days)

B.Musch arXiv:0907.2381

<kx> = −60(5) MeV for down quarks <kx> = 16(5) MeV for up quarks

B. Pasquini hep-ph/0806.2298

SSA for longitudinally polarized target

sin f asymmetry for long.pol. target are comparable for p0 & p+ while - p SSA seem to have an opposite sign indicating significant Collins type contribution.

Kotzinian et al (1999) hep-ex/0104005

CLAS PRELIMINARY

Efremov et al (2001)Zhun Lu et al (2013)

SSA for longitudinally polarized beam

ALU CLAS @4.3 GeV (2003)

Efremov et al (2003)

The force on a quark polarized in the x-direction with kT in the y-direction right after scattering Burkardt (2008),Qiu(2011)

W. Mao, Z. Lu (arXiv:1210.4790)

W. Gohn

CLAS 5.5 GeV

Sivers type contribution may dominate the p0 SSAsCollins type contribution seem to dominate the p-SSA

CLAS 5.7 GeV(p0)

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

18

Beam Polarimetry(Møller + Compton)

LuminosityMonitor

XKeeHe ),(3 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, For both p+ and p-, consistent with zero within uncertainties.

Preliminary Results

In models, directly related to OAM,L=0 and L=2 interference

Analysis by Y. Zhang (Lanzhou) and X. Qian (Caltech)

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

Preliminary

vertical target

ShNUT PxlSσ sin∼

Analysis by K, Allada (JLab), Y. Zhao (USTC)

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

Preliminary

Preliminary

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’) Vertically polarized target

• 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)

Future: TMD study 12 GeV JLab

Precision Study of TMDsIn the Valence Quark Region

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

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

•GEMs for tracking •Cherenkov and EM

Calorimeter for electron PID •Heavy Gas Cherenkov and

MRPC (TOF) for pion PID

•CLEOII Magnet (official)•Draft pCDR just completed

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 (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: )

• 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

Summary on SoLID 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.• Study factorization with x and z-dependences • Study PT dependence• 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

Summary

• Nucleon Spin and TMD study have been exciting and fruitful• Recent and Preliminary Results from JLab with transversely polarized

targets: g2, TMDs • JLab 12 GeV

Planned SoLID program with JLab12 Precision 4-d mapping of TMD asymmetries

• Longer-term future: EIC in US, China and Europe Exciting new opportunities

Precision experimental data + development in theory for Nucleon TMDs +… lead to breakthrough in understanding QCD?

Backup Slides

High Luminosity polarize target: L(n) = 1036 cm-2 s-1(achieved), 1037 cm-2 s-1 (R&D) Compact size: No cryogenic support needed Proton dilution measured experimentally

Polarized 3He Target

BeamPolarimetry

LuminosityMonitor

Beam

3HeCell

~90% ~1.5% ~8%

High luminosity: L(n) = 1036 cm-2 s-1

Record high 50-65% polarization in beam with automatic spin flip / 20min <P> = 55.4% ± 0.4% (stat. per spin state) ± 2.7 % (sys.)

Performance of 3He Target

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

Preliminary

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

JLab Physics Program at 12 GeV

43

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

Map Collins and Sivers asymmetries in 4-D (x, z, Q2, PT)

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 3He

Asymmetry projection for one M-z bin

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+

Hiayan Gao (Duke)

EIC@HIAF reach high precision similar to SoLID at lower x, higher Q2 region