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Nucleon Structure Study with e-N

Nucleon Structure Study with e-N. Jian -ping Chen ( 陈剑平 ), Jefferson Lab, Virginia, USA EIC 物理研讨会 , Weihai , China, July 29, 2013. Introduction Polarized e-N facilities: JLab /12 GeV , EIC, … Examples of Golden Physics Cases Spin Structure

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Nucleon Structure Study with e-N

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  1. Nucleon Structure Study with e-N Jian-ping Chen (陈剑平), Jefferson Lab, Virginia, USA EIC 物理研讨会 ,Weihai, China, July 29, 2013 • Introduction • Polarized e-N facilities: JLab/12 GeV, EIC, … • Examples of Golden Physics Cases • Spin Structure • 3-d Structure of the Nucleon (GPDs, TMDs) • p/K Structure Functions • others: Form Factor, Hadron Spectroscopy, Parity Violation e-N • Unique Opportunities for EIC@HIAF

  2. Introduction Nucleon Structure ,QCDand e-N

  3. Major Challenge: Non-perturbative QCD/Confinement running coupling “constant” • 2004 Nobel prize for ``asymptotic freedom’’ • non-perturbative regime QCD ? confinement • 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

  4. History of Nucleon Structure Study • 1933: First (Indirect) Evidence of Proton Structure magnetic moment of the proton:mp=eћ/2mpc(1+kp) ! anomalous magnetic moment: kp= 1.5 +- 10% • 1960s: Discovery: Proton Has Internal Structure elastic electron scattering • 1970s: Discovery of Quarks (Partons) deep-inelastic scattering • 1970s-2000s: Parton Distributions • 1980s-2010s: Spin Distributions • 2000s-: 3-d Structure Otto Stern Nobel Prize 1943 Robert Hofstadter, Nobel Prize 1961 J.T. Friedman R. Taylor H.W. Kendall Nobel Prize 1990

  5. Nucleon Structure: A Universe Inside • Nucleon: proton =(uud) , neutron=(udd) + sea + gluons • Global properties and structure: full of surprises Mass: 99% of the visible mass in universe ~1 GeV, but u/d quark mass only a few MeV each! Lattice QCD: vacuum condensation Charge and magnetic distributions: very different Momentum: quarks carry ~ 50% Spin: ½, but total quarks contribution only ~30% Orbital angular momentum is important Transverse (3-d) structure: GPDs and TMDs …

  6. Nucleon Structure Function: Deep-Inelastic Scattering • Bjorken Scaling and Scaling Violation • Gluon radiation – QCD evolution • One of the best experimental tests of QCD

  7. QCD and Nucleon Structure Study • Dynamical Chiral Symmetry Breaking <-> Confinement ? • Responsible for ~98% of the nucleon mass • Higgs mechanism is (almost) irrelevant to light quarks • Rapid development in theory • Lattice QCD • Dyson-Schwinger • Ads/CFT: Holographic QCD • …… • Direct comparisons limited to • Moments • Tensor charge • … • Direct comparison becomes possible • Experimental data with predictions from theory C.D. Roberts, Prog. Part. Nucl. Phys. 61 (2008) 50 M. Bhagwat & P.C. Tandy, AIP Conf.Proc. 842 (2006) 225-227 Mass from nothing!

  8. Imaging dynamical chiral symmetry breaking: pion wave function on the light front, Lei Chang, et al., arXiv:1301.0324 [nucl-th], Phys. Rev. Lett. 110 (2013) 132001 (2013) [5 pages]. Dyson-Schwinger Pion’s valence-quark Distribution Amplitude C.D. Roberts, Prog. Part. Nucl. Phys. 61 (2008) 50 Dilation of pion’s wave function is measurable in pion’s electromagnetic form factor at JLab12 A-rated:E12-06-10 • Established an one-to-one connection between DCSB and the pointwise form of the pion’s wave function. • Dilation measures the rate at which dressed-quark approaches the asymptotic bare-parton limit • Experiments at JLab12 can empirically verify the behaviour of M(p), and hence chart the IR limit of QCD Craig Roberts: Mapping Parton Structure and Correlations (62p)

  9. New progress in Lattice QCD X. Ji • Using the Infinite Momentum Frame formalism. • Start with static correlation in the z-direction. • Can be extended to TMDs and GPDs. First exploratory study by Huey-Wen Lin presented at the QCD Evolution Workshop at JLab, May 2013.

  10. Lepton-Nucleon Facilities JLab 6 GeV/12 GeV, EIC

  11. Jefferson Lab at a Glance • CEBAF • High-intensity electron accelerator based onCW SRFtechnology • Emax = 6 GeV • Imax = 200 mA • Polmax = 85% • L~ 1039 (unpolarized) • ~ 1036-1037(polarized) 12 GeV • ~ 1400 Active Users • ~ 800 FTEs • 178 Completed Experiments @ 6 GeV • Produces ~1/3 of US PhDs in Nuclear Physics C A B A C B

  12. 12 GeV Upgrade The completion of the 12 GeV Upgrade of CEBAF was ranked the highest priority in the 2007 NSAC Long Range Plan. Add 5 cryomodules New Hall 20 cryomodules CHL-2 Add arc 20 cryomodules Add 5 cryomodules • Enhanced capabilities in existing Halls • High Luminosity • 1035 - ~1039 cm-2s-1 Maintain capability to deliver lower pass beam energies : 2.2, 4.4, 6.6,….

  13. JLab Physics Program at 12 GeV Hall A Hall A – form factors, GPDs & TMDs , SRC Low-energy tests of the SM and Fund. Symmetry Exp SoLID, MOLLER. Hall B High luminosity, high resolution & dedicated equipments Hall B - 3-D nucleon structure via GPDs & TMDs Search new form of hadron. matter via Meson Spectr. 4p detector Hall C Hall C– precision determination of valence quark properties in nucleons and nuclei Hermetic detector Photon tagger high momentum spectrometers & dedicated equipments Hall D - exploring origin of confinement by studying exotic mesons using real photons Hall D

  14. H1, ZEUS Kinematics Coverage of the 12 GeV Upgrade H1, ZEUS 27 GeV 11 GeV 11 GeV 200 GeV JLab Upgrade JLab @ 12 GeV COMPASS W = 2 GeV HERMES The 12 GeV Upgrade is well matched to studies in the valence quark regime. 0.7

  15. EIC: Science Motivation A High Luminosity, High Energy Electron-Ion Collider: A New Experimental Quest to Study the Sea and Glue How do we understand the visible matter in our universe in terms of the fundamental quarks and gluons of QCD? Precisely image the sea-quarks and gluons in the nucleon: • How do the gluons and sea-quarks contribute to the spin structure of the nucleon? • What are the 3d distributions of the gluons and sea quarks in the nucleon? • How do hadronic final-states form in QCD? Explore the new QCD frontier: strong color fields in nuclei: • How do the gluons contribute to the structure of the nucleus? • What are the properties of high density gluon matter? • How do fast quarks or gluons interact as they traverse nuclear matter?

  16. 2010 NRC Decadal Study

  17. Electron Ion Colliders on the World Map EIC@HIAF LHC  LHeC RHIC  eRHIC CEBAF  MEIC/EIC HERA FAIR  ENC

  18. The Landscape of EIC • An EIC aims to study gluon dominated matter. • With 12 GeV we study mostly the valence quark component mEIC EIC 12 GeV

  19. Lepton-Nucleon Facilities HIAF: e(3GeV) +p(12GeV), both polarized, L(max)=4*1032cm2/s JLAB12 HIAF

  20. Figure of Merit • Figure-of Merit for double polarization FOM=L * Pe2 * PN2 * D2 L=Luminosity, P=Polarization, D=Dilution • FOM Comparison of EIC@HIAF (1) with COMPASS (2) HIAF: L=4*1032, D=1 COMPASS: L=1032, D=0.13 (NH3 target) Unpolarized: FOM(1)/FOM(2) = L(1)/L(2) ~ 4 Polarized: FOM(1)/FOM(2) = L(1)/L(2) * [D(1)2 /D(2)2] ~ 200

  21. Medium Energy EIC@JLab • JLab Concept • Initial configuration (MEIC): • 3-12 GeV on 20-100 GeVep/eAcollider • Fully-polarized, longitudinal and transverse • Luminosity: up to few x 1034 e-nucleons cm-2s-1 • Upgradable to higher energies • 250 GeVprotons + 20 GeV electrons

  22. MEIC: FullAcceptance Detector 7 meters detectors solenoid ion FFQs ion dipole w/ detectors ions IP 0 mrad electrons electron FFQs 50 mrad 2+3 m 2 m 2 m Three-stage detection Central detector TOF Detect particles with angles below 0.5obeyond ion FFQs and in arcs. Need 4 m machine element free region Detect particles with angles down to 0.5obefore ion FFQs. Need 1-2 Tm dipole. Solenoid yoke + Muon Detector RICH or DIRC/LTCC Tracking RICH EM Calorimeter HTCC 4-5m Muon Detector Hadron Calorimeter EM Calorimeter Very-forward detector Large dipole bend @ 20 meter from IP (to correct the 50 mr ion horizontal crossing angle) allows for very-small angle detection (<0.3o). Need 20 m machine element free region Solenoid yoke + Hadronic Calorimeter 2m 3m 2m

  23. MEIC Point Design Parameters

  24. Ongoing MEIC Accelerator R&D • Space Charge Dominated Ion Beam in the Pre-booster • Simulation study is in progress by Argonne-NIU collaborators • Beam Synchronization • A scheme has been developed; SRF cavity frequency tunability study is in progress • Beam-Beam Interaction • Phase 1 simulation study was completed • Interaction Region, Chromaticity Compensation and Dynamic Aperture • Detector integration with IR design has been completed, offering excellent acceptance • Correction scheme has been developed, and incorporated into the IR design • Tracking simulations show excellent momentum acceptance; dynamic aperture is increased • Further optimization in progress (e.g., all magnet spaces/sizes defined for IR +/- 100 m) • Beam Polarization • Electron spin matching and tracking simulations are in progress, achieving acceptable equilibrium polarization and lifetime (collaboration with DESY) • New ion polarization scheme and spin rotators have been developed (collaboration with Russian group) – numerical demonstration of figure-8 concept with misalignments ongoing • Electron Cloud in Ion Ring • Ion Sources (Polarized and Universal)

  25. Proposed Cooling Experiments at IMP • Idea: pulse the beam from the existing thermionic gun using the grid (HongweiZhao) • Non-invasive experiment to a user facility Proposed experiments • Demonstrate cooling of a DC ion beam by a bunched electron cooling (Hutton) • Demonstrate a new phenomena: longitudinal bunching of a bunched electron cooling (Hutton) • (Next phase) Demonstrate cooling of bunched ion beams by a bunched electron beam(need an RF cavity for bunching the ion beams) DC cooler Two storage rings for Heavy ion coasting beam

  26. EIC Realization Imagined Assumes endorsement for an EIC at the next NSAC Long Range Plan Assumes relevant accelerator R&D for down-select process done around 2016

  27. Phase Space for Polarized Data/EIC (x,Q2) phase space directly correlated with s (=4EeEp) : @ Q2 = 1 lowest x scales like s-1 @ Q2 = 10 lowest x scales as 10s-1 x = Q2/ys

  28. EIC@HIAF Kinematic Coverage Comparison with JLab 12 GeV e(3GeV) +p(12GeV), both polarized, L(max)=4*1032cm2/s • EIC@HIAF: • study sea quarks (x > 0.01) • deep exclusive scattering at Q2 > 5-10 • higher Q2 in valance region • range in Q2 allows study gluons • plot courtesy of Xurong Chen

  29. Science Goals The Science of eRHIC/MEIC Goal: Explore and Understand QCD: Map the spin and spatial structure of quarks and gluons in nucleons Discover the collective effects of gluons in atomic nuclei (role of gluons in nuclei & onset of saturation) Emerging Themes: Understand the emergence of hadronic matter from quarks and gluons & EW The Science of EIC@HIAF One Main Goal: Explore Hadron Structure Map the spin-flavor, multi-d structure of sea & valence quarks

  30. Science Case (I): Nucleon Spin-Flavor Structure Polarized Sea Quark

  31. Three Decades of Nucleon Spin Structure Study • 1980s: EMC (CERN) + early SLAC quark contribution to proton spin is very small DS = (12+-9+-14)% !‘spin crisis’ • 1990s: SLAC, SMC (CERN), HERMES (DESY) DS = 20-30% the rest: gluon and quark orbital angular momentum spin sum rule: (½)DS + Lq + JG =1/2 (Ji) others: Jaffe, Chen et al., … Bjorken Sum Rule verified to <10% level • 2000s: COMPASS (CERN), HERMES, RHIC-Spin, JLab, … : • DS ~ 30%; DGprobably small (~0.1)?,orbital angular momentum significant? • Valence quark structure • Transverse Spin, TMDs • GPDs

  32. Polarized Structure Function/Distributions

  33. JLab E99117: Precision Measurement of A1n at High-x PRL 92, 012004 (2004) , PRC 70, 065207 (2004) Physics News Update, Science Now Science News, Physics Today Update

  34. Planned JLab 12 GeV Experiments A1p at 11 GeV

  35. Sea Quark Polarization } Kinney, Seele • Spin-Flavor Decomposition of the Light Quark Sea 100 days, L =1033, s = 1000 Access requires s ~ 100-1000 (and good luminosity) Xiaodong Jiang (Los Alamos) is doing simulation with parameters of EIC@HIAF

  36. What can be achieved for Δg? how effective are scaling violations at the EIC… what about the uncertainties on the x-shape …

  37. Spin-Flavor Study at EIC@HIAF • Unique opportunity for Ds energy reach current fragmentation region for Kaon tagging in SIDIS • Significant improvement for Du_bar, Dd_barfrom SIDIS combination of energy and luminosity • Increase in Q2 range/precision for g1 (and g2) constraint on Dg.

  38. Science Case (II): 3-D Structure Generalized Parton Distributions

  39. Unified View of Nucleon Structure d2kT drz d3r TMD PDFs f1u(x,kT), .. h1u(x,kT)‏ GPDs/IPDs 5D Dist. Wpu(x,kT,r ) Wigner distributions (X. Ji ) 3D imaging dx & Fourier Transformation d2kT d2rT Form Factors GE(Q2), GM(Q2)‏ PDFs f1u(x), .. h1u(x)‏ 1D

  40. 3-D 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)

  41. b - Impact parameter T uX(x,b ) u(x,b ) dX(x,b ) d(x,b ) T T T T quark flavor polarization Needs: Hu Eu Ed Hd 3D Images of the Proton’s Quark Content M. Burkardt PRD 66, 114005 (2002) transverse polarized target Accessed in Single Spin Asymmetries.

  42. Quark distribution q(x) Accessed by beam/target spin asymmetry -q(-x) Accessed by cross sections t=0 Access GPDs through DVCS x-section & asymmetries DIS measures at x=0

  43. Quark Angular Momentum → Access to quark orbital angular momentum

  44. L = 2x1035 cm-2s-1 T = 1000 hrs DQ2 = 1GeV2 Dx = 0.05 e p epg E = 11 GeV CLAS12-DVCS/BH Target Asymmetry Longitudinally polarized target ~ Ds~sinfIm{F1H+x(F1+F2)H...}df CLAS preliminary AUL E=5.75 GeV <Q2> = 2.0GeV2 <x> = 0.2 <-t> = 0.25GeV2

  45. Detailed differential images from nucleon’s partonic structure EIC: Gluon size from J/Y and felectroproduction (Q2 > 10 GeV2) Hints from HERA: Area (q + q) > Area (g) Dynamical models predict difference: pion cloud, constituent quark picture - [Transverse distribution derived directly from tdependence] t t Weiss, Hyde, Horn EIC: singlet quark size from deeply virtual compton scattering Fazio EIC: strange and non-strange (sea) quark size from p and K production • Q2 > 10 GeV2 • for factorization • Statistics hungry • at high Q2! Horn

  46. Charles Hyde (ODU)

  47. GPD Study at EIC@HIAF • Unique opportunity for DVMP (pion/Kaon) flavor decomposition needs DVMP energy reach Q2 > 5-10 GeV2, scaling region for exclusive light meson production (JLab12 energy not high enough to have clean meson deep exclusive process) • Significant increase in range for DVCS combination of energy and luminosity • Other opportunities: vector meson, heavy flavors?

  48. Science Case (III): 3-D Structure Transverse Momentum-Dependent Distributions (HaiyanGao’s talk)

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