1. Physics Program with JLab 12 GeV Energy Upgrade J. P. Chen, Jefferson Lab, Virginia, USA USTC, Hefei, China, August 3, 2010  Introduction  Electron Scattering Experiments: JLab 6 GeV Facility and Instrumentation JLab 12 GeV Upgrade and Beyond (EIC)  Selected Example of 12 GeV Program  Transverse Spin and Transverse Structure  Parity Violation Electron Scattering

2. Standard Model

3. What are the challenges? Success of the Standard Model Electro-Weak theory tested to very good level of precision QCD tested in the high energy (short distance) region Major challenges: Test QCD in the strong interaction region (distance of the nucleon size) Understand quark-gluon structure of the nucleon Confinement Beyond Standard Model Energy reach: LHC search Higgs? Supersymmetry? String Theory? … Search for dark matter, dark energy, … Precision: test Standard Model at low energy

4. 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

5. Nucleon Structure and QCD Nucleon: quarks and gluons with strong interaction (QCD) Strong interaction, running coupling ~1 -- asymptotic freedom (2004 Nobel) perturbation calculation works only at high energy interaction negligible -- interaction significant at intermediate energy quark-gluon correlations -- confinement interaction strong at low energy coherent hadron -- Chiral symmetry Confinement ?

6. Nucleon Structure Nucleon: proton =(uud), neutron=(udd) + sea + gluons Global properties and structure: full of suprises Mass: 99% of the visible mass in universe ~1 GeV, but u/d quark mass only a few MeV each! Charge and magnetic distributions: different! Proton charge radius: muonic hydrogen Lamb shift result! (Nature 466, 213 (2010) ) Momentum: quarks carry ~ 50% Spin: ½, but total quarks contribution only ~30%! Spin Sum Rule? Magnetic moment: large part is anomalous, >150%! GDH Sum Rule Axial charge Bjorken Sum Rule Tensor charge Transverse Spin Sum Rule? …

7. Electron Scattering and Nucleon Structure Clean probe to study nucleon structure only electro-weak interaction, well understood Elastic Electron Scattering: Form Factors  60s: established nucleon has structure (Nobel Prize) electrical and magnetic distributions Resonance Excitations  internal structure, rich spectroscopy (new particle search) constituent quark models, … Deep Inelastic Scattering  70s: established quark-parton picture (Nobel Prize) parton distribution functions

8. Invariant mass squared Unpolarized: 4-momentum transfer squared Inclusive Electron Scattering F 1 and F 2 : information on the nucleon/nuclear structure

9. Elastic Quasielastic  N*N* Deep Inelastic Nucleus Elastic  N*N* Deep Inelastic Proton Typical Electron Scattering Spectra at Fixed Q 2

10. JLab Facility 6 GeV CEBAF, 3 Experimental Halls

11. Thomas Jefferson National Accelerator Facility Newport News, Virginia, USA One of two primary DOE nuclear/hadronic physics laboratories 6 GeV polarized CW electron beam (P = 85%, I = 200  A) 3 halls for fixed-target experiments

12. CEBAF @ JLab Today Superconducting recirculating electron accelerator maximum energy 6 GeV maximum current 200  A electron polarization85% Experiment running ~~9 months/yr Equipment in 3 halls (simultaneous operation) L [cm -2 s -1 ] (pol) A: 2 High Resolution Spectrometers 10 39 (10 36 ) B: Large Acceptance Spectrometer 10 34 (10 34 ) C: 2 spectrometers and dedicated devices10 39 (10 35 ) JLab and User Community ~600 JLab employees ~1700 users from ~300 institutions, ~40 countries ~ 1/3 of the nuclear physics PhDs in US Experiment scale: ~100 collaborators (10-20 core), ~run for few months

13. JLab Accelerator Site

14. Jefferson Lab Experimental Halls HallA: two HRS’ Hall B:CLAS Hall C: HMS+SOS 6 GeV polarized CW electron beam Pol=85%, 180  A Will be upgraded to 12 GeV by ~2014

15. JLab Physics Program

16. JLab’s Scientific Mission How are the hadrons constructed from the quarks and gluons of QCD? What is the QCD basis for the nucleon-nucleon force? Where are the limits of our understanding of nuclear structure? Is the “Standard Model” complete? Critical issues in “strong QCD”: What is the mechanism of confinement? How and where does the dynamics of the q-g and q-q interactions make a transition from the strong (confinement) to the perturbative QCD regime? How does Chiral symmetry breaking occur? What is the multi-dimensional structure of the nucleon?

17. JLab 6 GeV Program Main physics programs nucleon electromagnetic form factors N N* electromagnetic transition form factors longitunidal spin structure of the nucleon Transverse spin and transverse structure exclusive reactions parity violation form factors and structure of light nuclei nuclear medium effects hypernuclear physics exotic states search ……

18. JLab 12 GeV Upgrade and beyond

19. 6 GeV JLab 12 CHL-2 Upgrade magnets and power supplies Enhance equipment in existing halls add Hall D (and beam line)

20. H1, ZEUS JLab Upgrade 11 GeV H1, ZEUS JLab @ 12 GeV 11 GeV 27 GeV 200 GeV W = 2 GeV Study of high x B domain requires high luminosity 0.7 HERMES COMPASS The 12 GeV Upgrade is well matched to studies in the valence quark regime.

21. Experimental Halls (new) Hall D: linear polarized photon beam, Selonoid detetcor ­ GluoX collaboration: exotic meson spectroscopy gluon-quark hybrid, confinement Hall B: CLAS12 ­ GPDs, TMDs… Hall C: Super HMS + existing HMS ­ Form factors, structure functions, … Hall A: Dedicated devices + existing spectrometers ­ Super BigBite, Solenoid Spectrometer (SOLID), Moller Spectrometer ­ SIDIS (TMDs), PVDIS, …

22. Physics Program for 12 GeV JLab search for origin of confinement (GlueX, exotic mesons) determine quark-gluon structure of the nucleon and nuclear matter via parton distributions in valence region transverse spin and transverse structure (TMDs) exclusive processes (DVCS, meson production) to study GPDs quark structure of nuclei Precision test of standard model to search for new physics Defining the Science Program: Four Program Advisory Committees (PAC) 30, 32, 34, 35 (2006-2010) 32 experiments approved ; 13 conditionally approved

23. 12 GeV Upgrade Schedule Two short parasitic installation periods in FY10 6-month installation May-Oct 2011 12-month installation May 2012-May 2013 Hall A commissioning start October 2013 Hall D commissioning start April 2014 Halls B and C commissioning start October 2014 Project Completion June 2015 23 R. McKeown – Hadron Workhop - Beijing

24. Jlab 12 GeV Upgrade An exciting scientific opportunity  Explore the physical origins of quark confinement (GlueX)  New access to the spin and flavor structure of the proton and neutron  Reveal the quark/gluon structure of nuclei  Probe potential new physics through high precision tests of the Standard Model Strong User community involvement  NSF MRI and NSERC funding to universities for detector elements  Strong international collaborations  32 PAC-approved experiments Accel-Civil-Physics scope leverages the existing facility Construction is well underway !  Accelerator nearing completion on major procurements; hardware arriving  Detector assembly ramping up  Civil construction on track New Proposals and collaborations are welcome

25. Beyond 12 GeV: ELIC at Beyond 12 GeV: ELIC at L ~ 10 35 cm -2 s -1 30-225 (5-100) GeV protons 30-100 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.

26. Examples of 12 GeV Program Search for exotic meson: GlueX Spin structure in valence region, GPDs, Hadronization, …

27. Quantum Numbers of Hybrid Mesons Quarks Excited Flux Tube Hybrid Meson like Exotic Flux tube excitation (and parallel quark spins) lead to exotic J PC

28. Lowest mass expected to be  1 (1 −+ ) at 1.9±0.2 GeV Lattice 1 -+ 1.9 GeV 2 +- 2.1 GeV 0 +- 2.3 GeV

29. Valence (high-x) A 1 n results spokesperson: J. P. Chen, Z. Meziani, P. Souder, PhD student: X. Zheng PRL 92, 012004 (2004), PRC 70, 065207 (2004 ) Physics News Update, 12/18/2003 ‘Bringing the Nucleon into Sharper Focus’ Science Now, 12/23/2003 ‘Quarks in a Surprising Spin’ Science News, 1/3/2004 ‘Topsy Turvy’ Physics Today Update, 2/2004 ‘Spinning the Nucleon into Sharper Focus’

30. Inclusive Hall A and B and Semi-Inclusive Hermes BBS BBS+OAM F. Yuan, H. Avakian, S. Brodsky, and A. Deur, arXiv:0705.1553 pQCD with Quark Orbital Angular Momentum

31. A 1 p at 11 GeV Projections for JLab at 11 GeV

32. W p u (x,k T,r ) Wigner distributions d2kTd2kT PDFs f 1 u (x),.. h 1 u (x)‏ GPDs/IPDs d 2 k T dr z d3rd3r TMD PDFs f 1 u (x,k T ),.. h 1 u (x,k T )‏ 3D imaging 6D Dist. Form Factors G E (Q 2 ), G M (Q 2 )‏ d2rTd2rT dx & Fourier Transformation 1D

33. t hard vertices A =           = Unpolarized beam, transverse target:  UT ~ sin  {k(F 2 H – F 1 E ) }d  E (  t)  LU ~ sin  {F 1 H + ξ(F 1 +F 2 ) H +kF 2 E }d  ~ Polarized beam, unpolarized target: H ( ,t ) ξ=x B /(2-x B ) Unpolarized beam, longitudinal target:  UL ~ sin  {F 1 H +ξ(F 1 +F 2 )( H +ξ/(1+ξ) E) }d  ~ H ( ,t ) ~ Cleanest process: Deeply Virtual Compton Scattering 33

34. DVCS beam asymmetry at 12 GeVCLAS12 ep ep  High luminosity and large acceptance allows wide coverage in Q 2 < 8 GeV 2, x B < 0.65, and t< 1.5GeV 2 Experimental DVCS program E12-06-119 was approved for the 12 GeV upgrade using polarized beam and polarized targets. sinφ moment of A LU

35. Quark propagation in cold and hot matter SIDIS A-A Collision E h = z  ~ 2 - 20 GeV E h = p T ~ 2 – 20 GeV (HERMES/JLab) (RHIC)

36. SIDIS to study hadronization Spokespersons: J.P. Chen, H. Lv, B. Norum, K. Wang Conditionally Approved Projected R M vs. z for  + and proton on 3 targets 12 C, 64 Cu, 184 W

37. Transverse Spin: Single Spin Asymmetries in SIDIS Transversity and TMDs

38. Unpolarized and Polarized Structure functions

39. Parton Distributions (CTEQ6 and DSSV) DSSV, PRL101, 072001 (2008) CTEQ6, JHEP 0207, 012 (2002) Polarized PDFs Unpolarized PDFs

40. Transversity Three twist-2 quark distributions: Momentum distributions: q(x,Q 2 ) = q ↑ (x) + q ↓ (x) Longitudinal spin distributions: Δq(x,Q 2 ) = q ↑ (x) - q ↓ (x) Transversity distributions: δq(x,Q 2 ) = 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 P T ) Distribution functions depends on x, k ┴ and Q 2 : δq, f 1T ┴ (x, k ┴,Q 2 ), … Fragmentation functions depends on z, p ┴ and Q 2 : D, H 1 (x,p ┴,Q 2 ) Measured asymmetries depends on x, z, P ┴ and Q 2 : Collins, Sivers, … (k ┴, p ┴ and P ┴ are related)

41. “Leading-Twist” TMD Quark Distributions Quark Nucleon Unpol. Long. Trans. Unpol. Long. Trans. Sivers transversity pretzelocityty worm-gear

42. Access TMDs through Hard Processes Partonic scattering amplitude Fragmentation amplitude Distribution amplitude proton lepton pion proton lepton antilepton Drell-Yan BNL JPARC FNAL EIC SIDIS electron positron pion e – e + to pions

43.  s=20 GeV, p T =0.5-2.0 GeV/c   0 – E704, PLB261 (1991) 201.   +/- - E704, PLB264 (1991) 462. Single Spin Asymmetries in Large transverse single-spin effects were observed at RHIC, at much higher CM energies. In collinear picture, the QCD predict small SSAs with transversely polarized protons colliding at high energies. Kane, Pumplin, Repko ‘78 FermiLab E-704 FNAL

44. Separation of Collins, Sivers and pretzelocity effects through angular dependence in SIDIS

45. A UT sin(  ) from transv. pol. H target Simultaneous fit to sin(  +  s ) and sin(  -  s ) `Collins‘ moments Non-zero Collins asymmetry Assume  q(x) from model, then H 1 _unfav ~ -H 1 _fav Need independent H 1 (BELLE) `Sivers‘ moments Sivers function nonzero (  + )  orbital angular momentum of quarks Regular flagmentation functions

46. Collins/Sivers asymmetries from COMPASS deuteron Phys. Lett. B 673 (2009) 127-135 u and d cancellation?

47. Transversity Distributions A global fit to the HERMES p, COMPASS d and BELLE e+e- data by the Torino group (Anselmino et al.). PRD 75, 054032 (2007)

48. Current Status Large single spin asymmetry in pp->  X Collins Asymmetries - sizable for 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 deuteron (COMPASS) Sivers Asymmetries - non-zero for  + from proton (HERMES), smaller for COMPASS? - consistent with zero for  - from proton and for all channels from deuteron - large for K + ? Very active theoretical and experimental study RHIC-spin, JLab (Hall A 6 GeV, CLAS12, HallA/C 12 GeV), Belle, FAIR (PAX) Global Fits/models by Anselmino et al., Yuan et al. and … First neutron measurement from Hall A 6 GeV (E06-010) Solenoid with polarized 3 He at JLab 12 GeV Unprecedented precision with high luminosity and large acceptance

49. JLab E06 ‑ 010 : First Neutron Transversity Measurement Spokespresons : X. Jiang, J. P. Chen, E. Cisbani, H. Gao, J.C. Peng 7 PhD Students: Y. Zhang (Lanzhou), J. Huang, Postdoc’s: Y. Qiang Polarized 3 He Target Polarized Electron Beam ~80% Polarization 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 49 Beam Polarimetry (Møller + Compton) Luminosity Monitor en→e’  X en→e’  X

51. Preliminary A LT Result Preliminary 3 He A LT – Systematic uncertainty is still under work – Projected neutron A LT stat. uncertainty : 6~10% Preliminary Systematic Uncertainty

52. Precision Study of Transversity and TMDs From exploration to precision study Transversity: fundamental PDFs, tensor charge TMDs provide multi-d structure information of the nucleon 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

53. Solenoid detector for SIDIS at 11 GeV FGEMx4 LGEMx4 LS Gas Cherenkov HG Aerogel GEMx2 SH PS Z[cm] Y[cm] Yoke Coil 3 He Target

54. 4-d Mapping of Collins/Sivers Asymmetries 12 GeV With SOLID (L=10 36 ) Both  + and  - For one z bin (0.5-0.55) Will obtain 8 z bins (0.3- 0.7)

55. Power of SOLID

56. Discussion Unprecedented precision 4-d mapping of SSA Collins and Sivers  +,  - and K +, K - Study factorization with x and z-dependences Study P T dependence With similar quality SIDIS data on the proton and data from e+e- extract transversity and fragmentation functions for both u and d quarks determine tensor charge study TMDs for valence quarks study quark orbital angular momentum Combining with world data, especially data from high energy facilities (future EIC) study Q 2 evolution (need theoretical development) sea and gluon TMDs (more surprises are waiting?) Global efforts (experimentalists and theorists), global analysis Precision information on multi-dimension nucleon structure

57. Particty Violating Electron Scattering Standard Model Tests

58. 1960s: An Electroweak Model of Leptons (and quarks) SU(2) L X U(1) Y gauge theory predicted the Z boson 1973: antineutrino-electron scattering First weak neutral current observation Mid-70s: first e-d DIS parity violation experiment at SLAC: Q 2 ~ 1 (GeV) 2 Central to establishing SU(2) L X U(1) Y Weak Neutral Current (WNC) Interactions Low energy Weak NC interactions (Q 2 <<M Z 2 ) Historical Context: Z0Z0 Established experimental technique:  (A PV ) < 10 ppm Cleanly observed weak-electromagnetic interference sin 2  W = 0.224 ± 0.020: same as in neutrino scattering

59. Parity-Violating (PV) Electron Scattering g unpolarized target - g V e and g A e are function of sin 2  W -  is a kinematic factor -g T : nucleon structure (QCD) to g = g A e g V T +  g V e g A T Leading contribution to parity-violating scattering asymmetry from interference of EM and weak amplitudes

60. Electron-Quark Phenomenology C 1u and C 1d will be determined to high precision by Q weak, Cs C 2u and C 2d are small and poorly known: one combination can be accessed in PV DIS New physics such as compositeness, leptoquarks: Deviations to C 2u and C 2d might be fractionally large A V V A

61. Low Energy Tests of the Standard Model

62. Sensitivity: C 1 and C 2 Plots Cs PVDIS Qweak PVDIS World’s data Precision Data 6 GeV

63. Precision Hadronic Physics with DIS PV Charge Symmetry Violation (CSV) at High x: clean observation possible? Globalfits allow 3 times larger effects Londergan & Thomas Direct observation of parton-level CSV: exciting! Implications for high energy collider pdfs Could explain significant portion of the NuTeV anomaly Londergan & Thomas, B. Ma,… d(x)/u(x) at as x  1 Longstanding QCD prediction Needs high precision without nuclear effects Higher Twist Quark-gluon correlations Difficult to extract from DIS structure functions DIS PV: ‘clean’ extraction of twist-4

64. SoLID Spectrometer Baffles GEM’s Gas Cerenkov Shashlyk

65. Summary Electron Scattering: A clean tool to study nucleon structure and QCD JLab facility and 12 GeV upgrade Examples of 12 GeV program Transversity and TMDs: spin-orbit and multi-parton correlations First neutron transversity measurement Precision 4-d mapping with SOLID at 12 GeV Parity violating electron scattering Standard model test Precision tool to study hadron structure

66. Nucleon Structure Simple Picture (Naïve Quark Model): proton = u u d, neutron = u d d Parton Model: valence quarks + sea (quark-antiquark pairs) + gluons Parton (Momentum) Distribution Functions quark: q(x), antiquark: (x), gluon: g(x) Parton (Longitudinal) Spin Distributions  q(x),  (x),  g(x), L (x) (orbital angular momentum) Transverse Spin Distributions (Transversity) and TMDs  q(x, k T ), d (x,k T ), …

67. JLab Polarization-Transfer Data (G En ) E02-012 Using polarized 3He target in Hall A, submitted to PRL Earlier data using recoil polarization and polarized deuteron target, Hall C

68. JLab Data on EM Form Factors Testing Ground for Theories of Nucleon Structure Proton Neutron Electric Magnetic

69. World Data near Q 2 ~0.1 GeV 2 Preliminary G M s = 0.28 +/- 0.20 G E s = -0.006 +/- 0.016 ~3% +/- 2.3% of proton magnetic moment ~0.2 +/- 0.5% of electric distribution HAPPEX-only fit suggests something even smaller: G M s = 0.12 +/- 0.24 G E s = -0.002 +/- 0.017

70. World data consistent with state of the art theoretical predictions Preliminary 16. Skyrme Model - N.W. Park and H. Weigel, Nucl. Phys. A 451, 453 (1992). 17. Dispersion Relation - H.W. Hammer, U.G. Meissner, D. Drechsel, Phys. Lett. B 367, 323 (1996). 18. Dispersion Relation - H.-W. Hammer and Ramsey-Musolf, Phys. Rev. C 60, 045204 (1999). 19. Chiral Quark Soliton Model - A. Sliva et al., Phys. Rev. D 65, 014015 (2001). 20. Perturbative Chiral Quark Model - V. Lyubovitskij et al., Phys. Rev. C 66, 055204 (2002). 21. Lattice - R. Lewis et al., Phys. Rev. D 67, 013003 (2003). 22. Lattice + charge symmetry -Leinweber et al, Phys. Rev. Lett. 94, 212001 (2005) & hep-lat/0601025

71. SIDIS to study hadronization Quark propagation

72. Multi-dimensional Distributions GPDs/IPDs H(x,r T ),E(x,r T ),.. d2kTd2kT d2kTd2kT TMDs f 1 u (x,k T ),.. h 1 u (x,k T )  Gauge invariant definition (Belitsky,Ji,Yuan 2003)  Universality of k T -dependent PDFs (Collins,Metz 2003)  Factorization for small k T. (Ji,Ma,Yuan 2005) W p u (k,r T ) “Mother” Wigner distributions d2rTd2rT PDFs f 1 u (x),.. h 1 u (x) quark polarization d2rTd2rT

73. 73 EIC projection: Proton π + (z = 0.3-0.7)

74. First Moment of g 1 n Spekespersons: J. P. Chen, A. Deur, F. Garibaldi; 1 st Perord analysis : H. Lv ChPT at low Q2, pQCD (OPE) at high Q2 Future test LQCD E94-010, from 3 He, PRL 92 (2004) 022301 E97-110, from 3 He, preliminary 1n1n Effective Coupling Extracted from Bjorken Sum A. Deur, V. Burkert, J. P. Chen and W. Korsch PLB 650, 244 (2007) and PLB 665, 349 (2008)

75. Neutron Spin Polarizabilities Spokespersons: G. Cates, J. P. Chen, Z. Meziani, 5 PhD students Significant disagreement between data and ChPT calculations for  LT  0  LT Q2 Q2 Q2 Q2 E94-010, PRL 93 (2004) 152301

76. Medium Effect: Coulomb Sum Rule Spokespersons: J. P. Chen, S. Choi and Z. E. Meziani PhD students: Y. Oh (Seoul), X. Yan (USTC), H. Yao (Temple), Probe a Nucleon inside a nucleus: Possible modification of the nucleons’ property inside nuclei

77. BC Sum Rule  LT Spin Polarizability E08-027 : A - rating by PAC33 Spokespersons: A. Camsonne, J. P. Chen, K. Slifer, PhD students: P. Zhu (USTC),… Septa Magnets for low Q 2 Transverse Polarized Proton Target p g 2 : central to knowledge of Nucleon Structure but remains unmeasured at low Q 2 —Critical input to Hydrogen Hyperfine Calculations —Violation of BC Sum Rule suggested at large Q 2 —State-of-Art  PT calcs fail dramatically for  LT Planned 6 GeV Experiment: Proton g 2 and  LT n

78. Anticipated statistical uncertainties for GEp(5)

79. JLab Polarization-Transfer Data Using Focal Plane Polarimeter in Hall A E93-027 PRL 84, 1398 (2000) E99-007 PRL 88, 092301 (2002) E04-108, arXiv:1005.3419v2 (2010)arXiv:1005.3419v2 Clear discrepancy between polarization transfer and Rosenbluth data Investigate possible theoretical sources for discrepancy  two-photon contributions Shape of the proton: It’s a Ball. No, It’s a Pretzel. Must Be a Proton. (K. Chang, NYT, May 6, 2003)

80. 12 GeV Upgrade Kinematical Reach Reach a broad DIS region Precision SIDIS for transversity and TMDs Experimental study/test of factorization Decisive inclusive DIS measurements at high-x Study GPDs