Study Transverse Spin and TMDs with SIDIS Experiments J. P. Chen, Jefferson Lab Hall A Physics Workshop, December 14, 2011 Introduction Transverse Spin and Transverse Momentum Dependent Distributions (TMDs) Exploration: initial results from JLab 6 GeV experiment Precision study in valence region: JLab12 GeV program Precision study of the sea/gluons : Future EIC QCD: still unsolved in non-perturbative region 2004 Nobel prize for ``asymptotic freedom non-perturbative regime QCD ????? One of the top 10 challenges for physics! QCD: Important for discovering new physics beyond SM Nucleon structure is one of the most active areas Nucleon Structure and QCD Colors are confined in hadronic system Nucleon: ideal lab to study QCD Nucleon = valence quarks (u u d or u d d) + sea + gluons Mass, charge, magnetic moment, spin, axial charge, tensor charge Decomposition of each of the fundamental quantities Mass: ~1 GeV, but u/d quark mass only a few MeV each! Momentum: quarks carry ~ 50% Spin: , quarks contribute ~30% Spin Sum Rule Orbital Angular Momentum Relations to TMDs and GPDs Tensor charge Lattice QCD Quarks and gluon field are in-separable Multi-parton correlations are important Beyond co-linear factorization Transverse dimension is crucial for understanding nucleon structure and QCD, help understanding confinement Three Decades of Spin Structure Study 1980s: EMC (CERN) + early SLAC quark contribution to proton spin is very small = ( )% ! spin crisis ( Ellis-Jaffe sum rule violated) 1990s: SLAC, SMC (CERN), HERMES (DESY) = 20-30% the rest: gluon and quark orbital angular momentum A + =0 (light-cone) gauge () + L q + G + L g =1/2 (Jaffe) gauge invariant () + Lq + J G =1/2 (Ji) (New decompositions: Chen et al., Wakamatsu, ) What observable directly corresponds to L z ~ b x X p y ? New progress, Ji/Yuan Bjorken Sum Rule verified to region - comparison with HERMES results good agreement 1/D NN NEW Transverity2011 Franco Bradamante COMPASS Sivers asymmetry 2010 data x > region - comparison with HERMES results NEW Status of Transverse Spin Study Large single spin asymmetry in pp-> X Collins Asymmetries - sizable for the proton (HERMES and COMPASS ) large at high x, - and has opposite sign unfavored Collins fragmentation as large as favored (opposite sign)? - consistent with 0 for the deuteron (COMPASS) Sivers Asymmetries - non-zero for + from proton (HERMES), new COMPASS data - consistent with zero for - from proton and for all channels from deuteron - large for K + ? Collins Fragmentation from Belle Global Fits/models: Anselmino, Prokudin et al., Vogelsang/Yuan et al., Pasquini et al., Ma et al., Very active theoretical and experimental efforts RHIC-spin, JLab (6 GeV and 12 GeV), Belle, FAIR, J-PARC, EIC, Initial Exploration at Hall A 6 GeV Transversity experiment E06-010 E06 010 Experiment Spokespersons: Chen/Evaristo/Gao/Jiang/Peng First measurement on n ( 3 He) Polarized 3 He Target Polarized Electron Beam, 5.9 GeV ~80% Polarization BigBite at 30 as Electron Arm P e = 0.7 ~ 2.2 GeV/c Upgraded detector package HRS L at 16 as Hadron Arm P h = 2.35 GeV/c Excellent PID for /K/p 7 Excellent PhD Students K. Allada, C. Dutta, J. Huang, J. Katich, X. Qian, Y. Wang, Y. Zhang (all graduated) 3 Hard-working Postdocs: A. Camsonne, Y. Qiang, V. Sulkosky Strong Contributions/Supports from Hall A Collaboration, Hall A and JLab 18 Beam Polarimetry (Mller + Compton) Luminosity Monitor JLab Polarized 3 He Target longitudinal, transverse and vertical Luminosity=10 36 (1/s) (highest in the world) High in-beam polarization ~ 60% Effective polarized neutron target 13 completed experiments 7 approved with 12 GeV (A/C) 15 uA History of Figure of Merit of Polarized 3 He Target High luminosity: L(n) = cm -2 s -1 Polarization in all 3 directions (L, T, V) Record high in-beam ~ 60% polarization Fast spin flip (every 20 minutes) Performance of 3 He Target Separation of Collins, Sivers and pretzelocity effects through angular dependence 3 He Target Single-Spin Asymmetry in SIDIS 3 He Sivers SSA: negative for +, 3 He Collins SSA small Non-zero at highest x for + Blue band: model (fitting) uncertainties Red band: other systematic uncertainties X. Qian et al., PRL 107: (2011) Neutron Results with Polarized 3He from JLab Collins asymmetries are not large, except at x=0.34 Sivers negative 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: Preliminary J. Huang et al., arXiv: , accepted to PRL Corrected for proton dilution, f p Predicted proton asymmetry contribution < 1.5% ( + ), 0.6% ( - ) Dominated by L=0 (S) and L=1 (P) interference Consist w/ model in signs, suggest larger asymmetry Neutron A LT Extraction Preliminary Trans-helictiy Precision TMD Study in the Valence Region SoLID SIDIS program with 12 GeV upgrade Precision Study of Transversity and TMDs From exploration to precision study Transversity: fundamental PDFs, tensor charge TMDs: 3-d structure in momentum space Spin-orbit correlations: quark orbital angular momentum Multi-parton correlations: QCD dynamics Multi-dimensional mapping of TMDs 4-d (x,z,P , Q 2 ) Multi-facilities, global effort Precision high statistics high luminosity and large acceptance Precision TMDs with SoLID (JLab) PAC 38 results: E : Neutron (3He) SSA in SIDIS with SoLID awarded the highest rating A Precision 4-d (x, z, PT, Q2) mapping of Collins/Sivers in valence region E : Neutron (3He) DSA and Longitudinal SSA in SIDIS with SoLID, A Precision map of A_LT and A_UL, worm-gear functions E : proton SSA in SIDIS with SoLID, conditional approval (target) Several TMD proposals in CLAS12 and Hall A/C approved A comprehensive and coherent program on TMDs GEMs (study done with CDF magnet, 1.5T) 29 E , Approved with A Rating Mapping of Collins(Sivers) Asymmetries with SoLID Spokespersons: Chen/Gao/Jiang/Peng/Qian Both + and - Precision Map in region x( ) z( ) Q 2 (1-8) P T (0-1.6) Dipole Shift in mom. space. Model Calculations -> h 1L =? -g 1T. h 1L = g 1T = Longi-transversity Trans-helicity Center of points: Discussion Unprecedented precision 4-d (x,z,P T,Q 2 ) mapping of SSA Collins, Sivers, worm-gear, other TMDs +, - and K +, K - Study factorization with x and z-dependences Study P T dependence On both proton and neutron and combine with world data (e+e-) extract transversity and fragmentation functions for both u and d quarks determine tensor charge study TMDs for valence quark region study quark orbital motion and spin-orbital correlations Need world data from high energy facilities (EIC,) study Q 2 evolution, sea quarks, gluons Global efforts (experimentalists and theorists), global analysis much better understanding of multi-d nucleon structure and QCD Lead to breakthroughs Precision TMD study: Sea and Gluons A Future Electron Ion Collider: ELIC, JLab Into the Sea: A Future Electron-Ion Collider 12 GeV With 12 GeV we study mostly the valence quark component. An EIC aims to study the sea quarks, gluons, and scale (Q 2 ) dependence. mEIC EIC Electron Ion Colliders on the World Map RHIC eRHIC LHC LHeC CEBAF MEIC/EIC FAIR ENC HERA Medium Energy Three compact rings: 3 to 11 GeV electron Up to 12 GeV/c proton (warm) Up to 60 GeV/c proton (cold) ELIC at ELIC at L ~ cm -2 s GeV protons GeV/n ions 3-11 GeV electrons 3-11 GeV positrons Green-field design of ion complex directly aimed at full exploitation of science program. EIC Phase Space Coverage An EIC with good luminosity & high transverse polarization is the optimal tool to to study this! Only a small subset of the (x,Q 2 ) landscape has been mapped here. Gray band: present knowledge Red band: EIC (1 ) Image the Transverse Momentum of the Quarks Exact k T distribution presently essentially unknown! Prokudin, Qian, Huang Prokudin Summary Transverse spin and TMDs crucial for full understanding of nucleon structure and QCD Initial explorations worldwide increasing interests JLab 6 GeV: initial results, first neutron (3He) measurement JLab 12 GeV plan: precision 4-d mapping in the valence region tensor charge Lattice QCD quark orbital motion QCD dynamics Electron-Ion Collider: understand sea and gluons Exciting new opportunities lead to breakthroughs? Acknowledgements: some slides provided by collaborators and colleagues