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: P T dependence of unpolarized flavor PDFs Results from Hall B (CLAS6) P T dependence of spin asymmetry A 1 SSA with longitudinal target or beam Recent and preliminary results Hall A (transversely Polarized 3 He (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 6 GeV  Produces ~1/3 of US PhDs in Nuclear Physics A B C CEBAF  High-intensity electron accelerator based on CW SRF technology  E max = 6 GeV  I max = 200  A  Pol max = 85% A B C  12 GeV

W p u (x,k T,r ) Wigner distributions d2kTd2kT PDFs f 1 u (x),.. h 1 u (x)‏ GPDs/IPDs d2kTd2kT d2rTd2rT TMD PDFs f 1 u (x,k T ),.. h 1 u (x,k T )‏ 3D imaging 5D Dist. Form Factors G E (Q 2 ), G M (Q 2 )‏ d2rTd2rT dx & Fourier Transformation 1D

Leading-Twist TMD PDFs f 1 = f 1T  = Sivers Helicity g 1 = h1 =h1 = Transversity h1 =h1 =Boer-Mulders h 1T  = Pretzelosity g 1T = Worm Gear h 1L  = Worm Gear : Probed with transversely pol target HERMES, COMPASS, JLab E Nucleon Spin Quark Spin

 Gold mine for TMDs  Access all eight leading-twist TMDs through spin-comb. & azimuthal- modulations  Tagging quark flavor/kinematics

Unpolarized TMDs Test x-z Factorization Flavor P T Dependence JLab Hall C SIDIS Results

From Form Factors to Transverse Densities up quark down quark byby bxbx bxbx byby

Unpolarized TMD: Flavor P T Dependence? A. Bacchetta, Jlab, arXiv (2013) up quark down quark kyky kyky kxkx kxkx

Flavor P T 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 f 1u/ f 1d kTkT

Hall C Results: Flavor P T Dependence C (d)2(d)2 (u)2(u)2 (-)2(-)2 (+)2(+)2

Results: from JLab Hall B (CLAS6) P T Dependence of A 1 SSA in Longitudinal Target SSA in Longitudinal Beam (plots courtesy of Harut Avagyan)

A 1 P T -dependence CLAS data suggests that width of g 1 is less than the width of f 1 Lattice PTPT arXiv: A 1 B.Musch et al arXiv:

Kotzinian-Mulders Asymmetries KM-TMD unique (no analog in GPDs) HERMES CLAS (5days) B.Musch arXiv: = −60(5) MeV for down quarks = 16(5) MeV for up quarks B. Pasquini hep-ph/

SSA for longitudinally polarized target sin  asymmetry for long.pol. target are comparable for    &    while  SSA seem to have an opposite sign indicating significant Collins type contribution. Kotzinian et al (1999) hep-ex/ CLAS PRELIMINARY Efremov et al (2001) Zhun Lu et al (2013)

SSA for longitudinally polarized beam A LU GeV (2003) Efremov et al (2003) The force on a quark polarized in the x-direction with k T in the y-direction right after scattering Burkardt (2008),Qiu(2011) W. Mao, Z. Lu (arXiv: )arXiv: W. Gohn CLAS 5.5 GeV Sivers type contribution may dominate the  0 SSAs Collins type contribution seem to dominate the  -SSA CLAS 5.7 GeV(  0)

Single Spin Asymmetries with A Transversely Polarized 3 He (n) JLab Hall A E Published and Preliminary Results From SIDIS and Inclusive Reactions

SIDIS: Separation of Collins, Sivers and pretzelocity effects through angular dependence

E06 ‑ 010 Experiment First measurement on n ( 3 He) Transversely Polarized 3 He Target Polarized Electron Beam, 5.9 GeV BigBite at 30º as Electron Arm – P e = 0.7 ~ 2.2 GeV/c HRS L at 16º as Hadron Arm – P h = 2.35 GeV/c – Excellent PID for  /K/p 18 Beam Polarimetry (Møller + Compton) Luminosity Monitor 7 PhD Thesis Students (graduated) + 2 new students

3 He (n) Target Single-Spin Asymmetry in SIDIS neutron Sivers SSA: negative for π +, Agree with Torino Fit neutron Collins SSA small Non-zero at highest x for  + Blue band: model (fitting) uncertainties Red band: other systematic uncertainties E collaboration, X. Qian at al., PRL 107:072003(2011)

Asymmetry A LT Result neutron A LT : Positive for  - Consist w/ model in signs, suggest larger asymmetry To leading twist: J. Huang et al., PRL. 108, (2012). Worm-Gear Dominated by L=0 (S) and L=1 (P) interference Trans helicity

Pretzelosity Results on Neutron 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 (A N ) Clear non-zero vertical target SSA Opposite sign for   and   Large for K + Preliminary vertical target Analysis by K, Allada (JLab), Y. Zhao (USTC)

E06-010: Inclusive Hadron SSA (A N ) Clear non-zero target SSA Opposite sign for   and     A N at low p T not very well understood Results consistent with predictions based on Sivers mechanism (valid at high p T ) Preliminary vertical target

Inclusive Target Single Spin Asymmetry: DIS 3 He θ e-e- Unpolarized e - beam incident on 3 He target polarized normal to the electron scattering plane. However, A y =0 at Born level,  sensitive to physics at order α 2 ; two-photon exchange. 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 3 He(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 TMDs In the Valence Quark Region

H 2 D 2 Hall C/SHMS L-T studies, precise  + /  - ratios Hall C/SHMS L-T studies, precise  + /  - ratios 3 He, NH 3 Hall A/SBS High x - Q 2, 2-3D Hall A/SBS High x - Q 2, 2-3D Hall A/SOLID High Lumi and acceptance – 4D Hall A/SOLID High Lumi and acceptance – 4D ULT q N U L T H 2 /D 2, NH 3 /ND 3, HD Hall B/CLAS12 General survey, medium luminosity Hall B/CLAS12 General 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

E /E , Both Approved with “A” Rating Mapping of Collins(Sivers) Asymmetries with SoLID Both  + and  - Precision Map in region x( ) z( ) Q 2 (1-8) P T (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  =

E : 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 -> h 1L  =? -g 1T. h 1L  = g 1T = Longi-transversity Trans-helicity Center of points:

Summary on SoLID TMD Program Unprecedented precision 4-d mapping of SSA Collins, Sivers, Pretzelosity and Worm-Gear Both polarized 3 He (n) and polarized proton with SoLID Three “A” rated experiments approved. One LOI on di-hadron. Study factorization with x and z-dependences Study P T 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 Q 2 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: g 2, 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) = cm -2 s -1 (achieved), cm -2 s -1 (R&D)  Compact size: No cryogenic support needed  Proton dilution measured experimentally Beam Polarimetry Luminosity Monitor Beam ~90% ~1.5% ~8%

 High luminosity: L(n) = cm -2 s -1  Record high 50-65% polarization in beam with automatic spin flip / 20min  = 55.4% ± 0.4% (stat. per spin state) ± 2.7 % (sys.)

E He Target Single-Spin Asymmetry in SIDIS 3 He Sivers SSA: negative for π +, 3 He Collins SSA small Non-zero at highest x for  + Blue band: model (fitting) uncertainties Red band: other systematic uncertainties X. Qian at al., PRL 107:072003(2011)

Asymmetry A LT Result 3 He A LT : Positive for  - To leading twist: J. Huang et al., PRL. 108, (2012). Worm-Gear.

Inclusive Hadron Electroproduction e + N ↑ h + X (h = , K, p) Why a non-zero A N is interesting? – Analogues to A N 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 A N in in the TMD framework pTpT

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% ++  False Asymmetry Preliminary

JLab 12 GeV Upgrade Maintain capability to deliver lower pass beam energies : 2.2, 4.4, 6.6,….  Enhanced capabilities in existing Halls  Increase of Luminosity ~10 39 cm -2 s -1  Enhanced capabilities in existing Halls  Increase of Luminosity ~10 39 cm -2 s -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. 4  detector Hall A – form factors, GPDs & TMDs, SRC Low-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 detector Photon tagger Hall A Hall B Hall C Hall D

Map Collins and Sivers asymmetries in 4-D (x, z, Q 2, P T )

 Access transversity in transversely polarized neutron target through π + π - di-hadron production  Run simultaneously with SIDIS 3 He (e,e’π ± )X  Systematical check of two approaches to access h 1 Asymmetry projection for one M-z bin

Green (Blue) Points: SoLID projections for polarized NH 3 ( 3 He/n) target Luminosity: (10 36 ) (1/cm 2 /s); Time: 120 (90) days Black points: projections for 3 GeV e and 12 GeV p Luminosity: 4 x /cm 2 /s; Time: 200 days The TMD simulation: Projections for SIDIS Asymmetry π + Hiayan Gao (Duke) reach high precision similar to SoLID at lower x, higher Q2 region