Understand how hadrons are constructed from the quarks and gluons of QCD

1. The Jefferson Lab 12-GeV Upgrade JLab’s Scientific Mission • Understand how hadrons are constructed from the quarks and gluons of QCD • Understand the QCD basis for the nucleon-nucleon force • Explore the limits of our understanding of nuclear structure • The transition from the nucleon-meson to the quark-gluon description We know that QCD works, but we still need to understand how. Must address critical issues in “strong” QCD • What is the mechanism of confinement? Where is the Glue? • Where does the dynamics of the q-q interaction make a transition from the strong (confinement) to the perturbative (QED-like) QCD regime? • How does the nucleon mass, spin, shape come about from the sea of gluons & quark/anti-quarks? • Do quarks and gluons play any direct role in Nuclear Matter?

2. Jefferson Lab Today • Provides unique capabilities for ~2000 member international user community to explore and understand the structure of matter at its most fundamental level (quarks and gluons). • The SRF electron accelerator provides CW beams of unprecedented quality with a maximum beam energy of 6 GeV. B C A • CEBAF’s innovative design allows delivery of beam with unique properties to three experimental halls simultaneously, increasing scientific output. • Each of the three halls offers complementary experimental capabilities and allows for large equipment installations to extend scientific reach.

3. 12 GeV Upgrade • Upgrade is designed to build on existing facility: • all accelerator and nearly all experimental equipment have continued use Add beam transport New Hall Scope of the proposed project includes doubling the accelerator beam energy, a new experimental Hall and associated beamline, and upgrades to the existing three experimental Halls. Enhanced capabilities in existing Halls

4. Architect’s Rendering of Hall D Complex Hall D Counting House Cryo Plant Service Buildings North East corner of Accelerator

5. Overview of 12 GeV Physics Program Hall D – exploring origin of confinement by studying exotic mesons Hall B – understanding nucleon structure via generalized parton distributions Hall C – precision determination of valence quark properties in nucleons and nuclei Hall A – short range correlations, form factors, hyper-nuclear physics, future new experiments

6. 20% of proton spin carried by quark spin • 50% of momentum carried by gluons

7. But miserable knowledge of especially d-quarks at large x and spin dependence at large x (here A1n is shown) Resolution: e.g., F2n tagging spectator proton from deuterium, and 3He(e,e’)

8. A1n at 11 GeV W>1.2 Unambiguous Resolution @ 12 GeV F2n/F2p at 11 GeV

9. Charged Pion Electromagnetic Form Factor Where does the dynamics of the q-q interaction make a transition from the strong (confinement) to the perturbative (QED-like) QCD regime? • It will occur earliest in the simplest systems •  the pion form factor Fp(Q2) provides our best chance to • determine the relevant distance scale experimentally To measure Fp(Q2) : • At low Q2 (< 0.3 (GeV/c)2): use p + e • scattering  Rrms = 0.66 fm • At higher Q2: use 1H(e,e’p+)n • Scatter from a virtual pion in the proton • and 1) extrapolate to the pion pole •  large uncertainty • 2) use a realistic pion • electroproduction model • In asymptotic region, F  8s ƒ2 Q-2

10. X. Ji, D. Mueller, A. Radyushkin (1994-1997) Proton form factors, transverse charge & current densities Structure functions, quark longitudinal momentum & helicity distributions Beyond form factors and quark distributions – Generalized Parton Distributions (GPDs) Correlated quark momentum and helicity distributions in transverse space - GPDs

11. x DIS at =t=0 = - - q H ( x , 0 , 0 ) q ( x ), q ( x ) ~ = D D - q ( x , 0 , 0 ) q ( x ), q ( x ) H Form factors (sum rules) ] [ 1 å ò x = q dx H ( x , , t ) F1 ( t )Dirac f.f. ~ ~ q x q q q q H , E , H , E ( x , , t ) ] [ 1 å ò x = q dx E ( x , , t ) F2 ( t )Pauli f.f. q 1 1 ~ ~ ò ò x = x = q q dx H ( x , , t ) G ( t ) , dx E ( x , , t ) G ( t ) , , A q P q - - 1 1 Link to DIS and Elastic Form Factors g t Quark angular momentum (Ji’s sum rule) 1 [ ] 1 1 ò = - J G = x + x q q q J xdx H ( , , 0 ) E ( x , , x 0 ) 2 2 - 1 X. Ji, Phy.Rev.Lett.78,610(1997)

12. DVCS: Single-Spin Asymmetry in ep  epg Measures phase and amplitude directly Eo = 11 GeV Eo = 6 GeV Eo = 4 GeV BH DVCS DVCS/BH comparable, allows asymmetry, cross section measurements DVCS and Bethe-Heitler are coherent  can measure amplitude AND phase DVCS at 11 GeV can cleanly test correlations in nucleon structure (data shown – 2000 hours)

13. r0 Exclusive r0 production on transverse target 2D (Im(AB*))/p T A ~ 2Hu + Hd AUT = - r0 |A|2(1-x2) - |B|2(x2+t/4m2) - Re(AB*)2x2 B ~ 2Eu + Ed AUT A~ Hu - Hd B ~ Eu - Ed r+ Asymmetry depends linearly on the GPDE, which enters Ji’s sum rule. K. Goeke, M.V. Polyakov, M. Vanderhaeghen, 2001 xB

14. Lattice calculation demonstrates reduction of chiral condensate of QCD vacuum in presence of hadronic matter The QCD Lagrangian and Nuclear “Medium Modifications” The QCD vacuum Long-distance gluonic fluctuations Does the quark structure of a nucleon get modified by the suppressed QCD vacuum fluctuations in a nucleus? Leinweber, Signal et al.

15. x Quark Structure of Nuclei: the EMC Effect • Observation that structure functions are altered in nuclei stunned much of the HEP community 24 years ago • ~1000 papers on the topic; the best models explain the curve by change of nucleon structure, BUT more data are needed to uniquely identify the origin What is it that alters the quark momentum in the nucleus? J. Ashman et al., Z. Phys. C57, 211 (1993) J. Gomez et al., Phys. Rev. D49, 4348 (1994)

16. g1(A) – “Polarized EMC Effect” • New calculations indicate larger effect for polarized structure function than for unpolarized: scalar field modifies lower components of Dirac wave function • Spin-dependent parton distribution functions for nuclei nearly unknown • Can take advantage of modern technology for polarized solid targets to perform systematic studies – Dynamic Nuclear Polarization

17. (polarized EMC effect) g1(A) – “Polarized EMC Effect” • New calculations indicate larger effect for polarized structure function than for unpolarized: scalar field modifies lower components of Dirac wave function • Spin-dependent parton distribution functions for nuclei nearly unknown • Can take advantage of modern technology for polarized solid targets to perform systematic studies – Dynamic Nuclear Polarization Curve follows calculation by W. Bentz, I. Cloet, A. W. Thomas

18. QCD and confinement High Energy Scattering Gluon Jets Observed Asymptotic Freedom Confinement Small Distance High Energy Large Distance Low Energy Strong QCD Perturbative QCD Spectroscopy Gluonic Degrees of Freedom Missing

19. Gluonic Excitations and the Origin of Confinement Hybrid mesons Theoretical studies of QCD suggest that confinement is due to the formation of “Flux tubes” arising from the self-interaction of the glue, leading to a linear potential (and therefore a constant force) Color Field: Because of self interaction, confining flux tubes form between static color charges Jpc = 1-+ 1 GeV mass difference Normal mesons Experimentally, we want to “pluck” the flux tube and see how it responds

20. Lattice QCD Flux tubes realized? Heavy Quarks Only! From G. Bali From D. Leinweber Confinement arises from flux tubes andtheir excitation leads to a new spectrum of mesons Rather like a “hole in the vacuum”, as also assumed in the Bag Model, now responsible for the famous “flux tube” of QCD.

21. Where is the Glue? Can JLab at 12 GeV find 1-+ Hybrids? What Mass? Models + Lattice QCD predict M ~ 2 GeV 12 GeV  9 GeV polarized photon beam  good “acceptance” up to M ~ 2.5 GeV How Strong? Calculations predict plenty of statistics Find plenty of glue in deep inelastic scattering, that has to end up in hadrons due to unitarity _ How Wide? No reason (yet) to believe qqg wider than qqq DM ~ 100-200 MeV How Brittle? Not known whether the string is brittle or not… Will there be a flux tube to excite, or will the string break? Regardless of the flux tube (here used as pedagogical example) there should be gluonic excitations with masses < 2 GeV

22. Why Photoproduction ? after before q q q q  beam Quark spins aligned q q q q Almost no data in hand in the mass region where we expect to find exotic hybrids when flux tube is excited before after Jpc = 1-+ Quark spins anti-aligned A pion or kaon beam, when scattering occurs, can have its flux tube excited  beam Much data in hand but little evidence for gluonic excitations (and not expected)

23. Finding the Exotic Wave Mass Input: 1600 MeV Width Input: 170 MeV Output: 1598 +/- 3 MeV Output: 173 +/- 11 MeV Double-blind M. C. exercise g V(ector Meson) S = 1 An exotic wave (JPC = 1-+) was generated at level of 2.5 % with 7 other waves. Events were smeared, accepted, passed to PWA fitter. Statistics shown here correspondto a few days of running.

24. Electron-Quark Phenomenology V A A V C1u and C1d will be determined to high precision by APV and Qweak C2u and C2d are small and poorly known: can be accessed in PV DIS New physics such as compositeness, new gauge bosons: Deviations in C2u and C2d might be fractionally large Proposed JLab upgrade experiment will improve knowledge of 2C2u-C2d by more than a factor of 20

25. 2H DIS Experiment at 11 GeV lab = 12.5o APV = 290 ppm E’: 6.8 GeV ± 10% 60 cm LD2 target Ibeam = 90 µA 800 hours xBj ~ 0.45 Q2 ~ 3.5 GeV2 W2 ~ 5.23 GeV2 1 MHz DIS rate, π/e ~ 1 HMS+SHMS (APV)=1.0 ppm (2C2u-C2d)=0.01 PDG: -0.08 ± 0.24 Theory: +0.0986

26. Møller Parity-Violating Experiment: New Physics Reach(example of large installation experiment with 11 GeV beam energy) JLab Møller LHC ee ~ 25 TeV New Contact Interactions LEP200 Complementary; 1-2 TeV reach ee ~ 15 TeV Kurylov, Ramsey-Musolf, Su Does Supersymmetry (SUSY) provide a candidate for dark matter? • Lightest SUSY particle (neutralino) is stable if baryon (B) and lepton (L) numbers are conserved • However, B and L need not be conserved in SUSY, leading to neutralino decay (RPV) 95% C.L. JLab 12 GeV Møller Examples:

27. Highlights of the 12 GeV Program • Revolutionize Our Knowledge of Spin and Flavor Dependence of Valence PDFs • Finalize Our Knowledge of Distribution of Charge and Current in the Nucleon • Totally New View of Hadron (and Nuclear) Structure: GPDs Towards the quark angular momentum • Exploration of QCD in the Nonperturbative Regime: • Existence and properties of exotic mesons • New Paradigm for Nuclear Physics: Nuclear Structure in Terms of QCD Spin and flavor dependent EMC Effect Study quark propagation through nuclear matter • Precision Tests of the Standard Model Factor 20 improvement in (2C2u-C2d)

28. 12 GeV Upgrade: Project Schedule(Feb ’06 CD-1 Documents) • 2004-2005 Conceptual Design (CDR) • 2004-2008 Research and Development (R&D) • 2006 Advanced Conceptual Design (ACD) • 2007-2009 Project Engineering & Design (PED) • 2008 Long Lead Procurement • 2008-2012 Construction • 2012-2013 Pre-Ops (beam commissioning)

29. 12 GeV Upgrade: Status • CD-0 approval March 31, 2004 • Period CD-0 to CD-1 is referred to as project “definition phase” • DOE Review of the Science of the 12 GeV Upgrade (April 6-8, 2005) • outstanding rating, several areas described as “discovery potential” • DOE Independent Project Review or IPR (July 12-14, 2005) • outstanding endorsement for CD-1 readiness from Lehman review in July • CD-1 Approval February 14, 2006 • Announcement at JLab by DOE Secretary Samuel Bodman • 12 GeV Upgrade featured in DOE Office of Science Five Year Plan • Completed “definition phase” • Period CD-1 to CD-4 is referred to as project “execution phase”

30. 12 GeV Upgrade: Status Near Term: • June 2006 Annual Project Review • Focus on preparations for CD-2B Performance Baseline • CD-2B Review anticipated for mid-2007 • August 2006 JLab PAC 30 • First review of 12 GeV proposals – “commissioning experiments” • Spokespersons make commitments to construction of equipment • Key first step in identifying the research interests and significant contributions of international collaborators • October 2006 – start Project Engineering & Design (PED)

31. 12 GeV Upgrade: The 12 GeV Upgrade, with its 1038+ luminosity, is expected to allow for a complete spin and flavor dependence of the valence quark region, both in nucleons and in nuclei. Long-Term: Electron-Light Ion Collider (ELIC) ELIC is designed to provide a complete spin and flavor dependence of the nucleon and nuclear sea, to study the explicit role gluons play in the nucleon spin and in nuclei, and open the new research territory of “gluon GPDs”.

32. ELIC@JLab Physics Specifications • Flexible Center-of-mass energy between 20 and 65 GeV • Ee ~ 3 GeV on Ei ~ 30 GeV up to Ee ~ 7 GeV on Ei ~ 150 GeV worked out in detail (gives Ecm up to 65 GeV) • CW Luminosity up to 8x1034 cm-2 sec-1 per Interaction Point • Ion species of interest: protons, deuterons, 3He, light-medium ions • Proton and neutron • Light-medium ions not necessarily polarized • Up to Calcium • Longitudinal polarization of both beams in the interaction region(+Transverse polarization of ions +Spin-flip of both beams)

33. Ion Linac and pre Ion Linac and pre Ion Linac and pre Electron Cooling - - - booster booster booster IR IR IR IR IR IR Snake Snake Snake Solenoid Solenoid Solenoid 3 3 3 - - - 7 GeV 7 GeV 7 GeV electrons electrons electrons 30 30 30 - - - 150 GeV light ions 150 GeV light ions 150 GeV light ions Electron Injector CEBAF with Energy Recovery CEBAF with Energy Recovery CEBAF with Energy Recovery Beam Dump Beam Dump Beam Dump ELIC@JLab Layout (Derbenev, Chattopadhyay, Merminga et al.) One accelerating & one decelerating pass through CEBAF

34. ELIC@JLab Realization Because ELIC is based on a completely new ring it is possible to optimize for spin preservation & handling and for high luminosity • Parameters have been pushed into new territory… • ß, lb, ring shape, crab crossing,… “ELIC proposes some very elegant and innovative features worth further investigation” (U. Wienands, EIC2004 Summary) The physics needs that drove us to this design are the importance of spin, a luminosity as high as possible, and a broad and flexible energy range for Hadron Physics Data from RHIC/RHIC-Spin, COMPASS, HERMES, JHF, JLab forthcoming to guide the requirements for key physics

35. Science Addressed by ELIC@JLab • Luminosity of up to 8x1034 cm-2 sec-1(one-day life time) • One day  4,000 events/pb • Supports Precision Experiments Lower value of x scales as s-1 • DIS Limit for Q2 > 1 GeV2 implies x down to 2.5 times 10-4 • Significant results for 200 events/pbfor inclusive scattering • IfQ2 > 10 GeV2 required for Deep Exclusive Processes can reach x down to 2.5 times 10-3 • Typical cross sections factor 100-1,000 smaller than inclusive scattering  high luminosity essential • How do quarks andgluons provide the binding and spin of the nucleons? • What is the quark-gluon structure of mesons? • How do quarks and gluons evolve into hadrons? • How does nuclear binding originate from quarks and gluons? • How do gluons behave in nuclei?

36. Examples: g1p,Transversity, Bjorken SR Examples: g1p EIC Monte Carlo Group • Antje Bruell (JLab) • Abhay Deshpande (SBU) • Rolf Ent (JLab) • Ed Kinney (Colorado) • Naomi Makins (UIUC) • Christoph Montag (BNL) • Joe Seele (Colorado) • Ernst Sichtermann (LBL) • Bernd Surrow (MIT) • + Several “one-timers”: Harut Avakian, • Dave Gaskell, • Andy Miller, … GRSV ELIC projection (~10 days) EIC Monte Carlo work by Naomi Makins Can determine the fundamental Bjorken Sum Rule to precision of better than 2%? (presently 10%) EIC Monte Carlo work by Antje Bruell + Mindy Kohler

37. ELIC@JLab – Conclusions • An excellent scientific case is developing for a high luminosity, polarized electron-light ion collider; will address fundamental issues in Hadron Physics: • The (spin-flavor) quark-gluon structure of the proton and neutron • How do quarks and gluons form hadrons? • The quark-gluon origin of nuclear binding • JLab design studies have led to an approach that promises luminosities as high as 8x1034 cm-2 sec-1(one day lifetime), for electron-light ion collisions at a center-of-mass energy between 20 and65 GeV • Evolutionary approach: 1x1033 cm-2 sec-1 1x1034 cm-2 sec-1  8x1034 cm-2 sec-1 • Multi-pronged R&D Strategy to illuminate details of the design • Conceptual development (“Circulator Ring”, Crab Crossing) • Analysis/Simulations • Experiments (ER at high I@JLab/FEL, ER at 1 GeV@CEBAF, High I source) • This design, using energy recovery on the JLab site, can be integrated with a 25 GeV fixed target program for physics

38. Backup Slides

39. N and N-D Form Factors @ 12 GeV GM(N-D) GEp 6 GeV GEn GMn • 6 GeV Projections  12 GeV Projections

40. Separated Structure Functions @ 12 GeV Rosenbluth Separations up to Q2 ~ 12  R = sL/sT | “DIS” (W2 > 4 GeV2) Limit

41. hard vertices x – quark momentum fraction • – longitudinal momentum transfer –t – Fourier conjugate to transverse impact parameter H(x,x,t), E(x,x,t), . . GPDs & Deeply Virtual Exclusive Processes “handbag” mechanism Deeply Virtual Compton Scattering (DVCS) x g x+x x-x t “Generalized Parton Distributions” Quark angular momentum (Ji’s sum rule) 1 [ ] 1 1 ò = - J G = x + x q q q J xdx H ( , , 0 ) E ( x , , x 0 ) 2 2 - 1 X. Ji, Phy.Rev.Lett.78,610(1997)

42. Ds 2s s+ - s- s+ + s- A = = Polarized beam, unpolarized target: ~ H(x,t) DsLU~ sinfIm{F1H+ x(F1+F2)H+kF2E}df x = xB/(2-xB) k = t/4M2 Kinematically suppressed Unpolarized beam, longitudinal target: ~ ~ H(x,t), H(x,t) DsUL~ sinfIm{F1H+x(F1+F2)(H+x/(1+x)E) -.. }df Kinematically suppressed Unpolarized beam, transverse target: H(x,t), E(x,t) DsUT~ sinfIm{k(F2H – F1E) + …..}df Kinematically suppressed Measuring GPDs through polarization

43. PV Asymmetries Weak Neutral Current (WNC) Interactions at Q2 << MZ2 Longitudinally Polarized Electron Scattering off Unpolarized Fixed Targets (gAegVT+gVegAT) • The couplings g depend on electroweak physics as well as on the weak vector and axial-vector hadronic current • With specific choice of kinematics and targets, one can probe new physics at high energy scales • With other choices, one can probe novel aspects of hadron structure

44. 12 GeV Technology Evolutionary upgrade in machine and experimental equipment: • cryomodule technology advancements • allow for nearly 100% increase in acceleration using only 25% additional space via higher gradient and increased effective accelerating length • Original CEBAF: 20 MV achieved • Present CEBAF average: 28 MV (max=34MV) achieved • SL21 (first prototype) 70 MV achieved • FEL3 (second prototype) 80 MV achieved • Renascence (final prototype) 98 MV (12 GeV requirement) testing underway • demonstrated detector technology for upgraded equipment • much Hall D detector technology well-developed by GlueX collaboration • Hall C SHMS detectors are copies of existing HMS detectors • most Hall B and Hall C magnet designs close to existing designs

45. New Capabilities in Halls A, B & C, and New Hall D D C 9 GeV tagged polarized photons and a 4 hermetic detector Super High Momentum Spectrometer (SHMS) at high luminosity and forward angles B A CLAS upgraded to higher (1035) luminosity and coverage High Resolution Spectrometer (HRS) Pair, and specialized large installation experiments

46. An Electron Ion Collider will allow us to look in detail into the sea of quarks and gluons, to create and study gluons, and to discover how energy transforms into matter From DOE 20-year plan 150 GeV proton 7 GeV electron One-event display from EIC Monte Carlo

47. The same electron accelerator can also provide 25 GeV electrons for fixed target experiments for physics • Implement 5-pass recirculator, at 5 GeV/pass, as in present CEBAF (straightforward upgrade, no accelerator R&D needed) • Luminosity of 1038+ • Complementary capabilities for broad class of experiments • Exploring whether collider and fixed target modes can run simultaneously (can in alternating mode)

48. Source requirements for ELIC less demanding with circulator ring! Few mA’s versus >> 100 mA of highly polarized beam. Towards Higher Electron Beam Current JLab FEL program with unpolarized beam ELIC with circulator ring @highest luminosity Lifetime Estimate @ 25 mA: CEBAF enjoys excellent gun lifetime: ~200 C charge lifetime (until QE reaches 1/e of initial value) ~100,000 C/cm2 charge density lifetime (we use a ~0.5 mm dia. spot) IfCharge-Lifetime assumptionvalid: With ~1 cm dia. spot size lifetime of 36 weeks at 25 mA! Ave. Beam Current (mA) Year Need to test the scalability of charge lifetime with laser spot diameter  Measure charge lifetime versus laser spot diameter in lab. (Poelker, Grames) First low polarization, then high polarization at CEBAF First polarized beam from GaAs photogun

49. 500 MeV 500 MeV 500 MeV 50 MeV 1 GeV 1 GeV ERL Technology demonstrated at CEBAF @ 1 GeV Special installation of a RF/2 path length delay chicane, dump and beamline diagnostics. 500 MeV 50 MeV ~1 GeV Accelerating beam ~55 MeV Decelerating beam

50. Gradient modulator drive signals with and without energy recovery in response to 250 sec beam pulse entering the RF cavity (SL20 Cavity 8) RF Response to Energy Recovery 250 ms without ER with ER