Future Research at Jefferson Lab 12 GeV and Beyond Kees de Jager Jefferson Lab INPC2007 Tokyo

1. Future Research at Jefferson Lab 12 GeV and Beyond Kees de Jager Jefferson Lab INPC2007 Tokyo June 3-8, 2007

2. Jefferson Lab Today • ~1200 active users worldwide engaged in exploring and understanding the quark-gluon structure of matter • The SRF electron accelerator provides CW beams of unprecedented quality (polarization of up to 85%) 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 • Each of the three halls offers complementary experimental capabilities and allows for large equipment installations

3. Highlights of the 12 GeV Program • Revolutionize Our Knowledge of Spin and Flavor Dependence of PDFS in the Valence Region • Totally New View of Hadron (and Nuclear) Structure: GPDs • Determination of the quark angular momentum • Exploration of QCD in the Nonperturbative Regime: • Existence and properties of QCD flux-tube excitations • New Paradigm for Nuclear Physics: Nuclear Structure in Terms of QCD • Spin- and flavor-dependent EMC Effect • Quark propagation through nuclear matter • Precision Tests of the Standard Model • Factor 20 improvement in (2C2u-C2d) axial-vector quark couplings • Determination of sin2w to within 0.00025

4. Examples of the 12 GeV Upgrade Research • Parton Distribution Functions • Generalized Parton Distributions and Form Factors • Exotic Meson Spectroscopy: Confinement and the QCD vacuum • Nuclei at the level of quarks and gluons • Tests of Physics Beyond the Standard Model

5. 12 GeV : Unambiguous Flavor Structure x —> 1 After 35 years: Miserable Lack of Knowledge of Valence d-Quarks Hall A at 11 GeV with BigBite pQCD di-quark correlations

6. Unambiguous Resolution of Valence Spin A1p at 11 GeV A1n at 11 GeV

7. Complements Spin-Flavor Dependence at RHIC At RHIC with W production At JLab with 12 GeV upgrade 12 Stops at x≈0.5 AND needs valence d(x)

8. Examples of the 12 GeV Upgrade Research • Parton Distribution Functions • Generalized Parton Distributions and Form Factors • Exotic Meson Spectroscopy: Confinement and the QCD vacuum • Nuclei at the level of quarks and gluons • Tests of Physics Beyond the Standard Model

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

10. What’s the use of GPDs? 1. Allows for a unified description of form factors and parton distributions 2. Allows for Transverse Imaging Fourier transform in momentum transfer x < 0.1 x ~ 0.3 x ~ 0.8 gives transverse size of quark (parton) with longitud. momentum fraction x 3. Allows access to quark angular momentum

11. Generalized Parton Distributions (GPDs): hard vertices Quark angular momentum (Ji’s sum rule) X. Ji, Phy.Rev.Lett.78,610(1997) Deeply Virtual Compton Scattering (DVCS) x – quark momentum fraction  – longitudinal momentum transfer √–t – Fourier conjugate to transverse impact parameter “handbag” mechanism Flavor separation through Deeply Virtual Meson Production e.g.

12. Exclusive 0 production on transverse target 0 A ~ 2Hu + Hd 0 B ~ 2Eu + Ed A~ Hu - Hd B ~ Eu - Ed + AUT Asymmetry depends linearly on the GPDE, which enters Ji’s sum rule K. Goeke, M.V. Polyakov, M. Vanderhaeghen, 2001 xB

13. Experiments at 11 GeV will extend EMFF data Neutron Proton Electric To 15 GeV2 To 5 GeV2 Magnetic To 15 GeV2

14. Examples of the 12 GeV Upgrade Research • Parton Distribution Functions • Generalized Parton Distributions and Form Factors • Exotic Meson Spectroscopy: Confinement and the QCD vacuum • Nuclei at the level of quarks and gluons • Tests of Physics Beyond the Standard Model

15. Flux Tubes and Confinement Color Field: Because of self interaction, confining flux tubes form between static color charges Notion of flux tubes comes about from model-independent general considerations. Idea originated with Nambu in the ‘70s

16. Hybrid mesons Hybrid mesons and mass predictions 1 GeV mass difference Normal mesons Jpc = 1-+ Lattice 1-+ 1.9 GeV 2+- 2.1 GeV 0+- 2.3 GeV Lowest mass expected to be 1(1−+) at 1.9±0.2 GeV

17. Why Photoproduction ? after before q q q q Quark spins aligned q q q q  beam Almost no data in hand in the mass region where we expect to find exotic hybrids when flux tube is excited after before 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)

18. Physics goals and key features The physics goal of GlueX is to map the spectrum of hybrid mesons starting with those with the unique signature of exotic JPC • Identifying JPC requires an amplitude analysis which in turn requires • linearly polarized photons • detector with excellent acceptance and resolution • sensitivity to a wide variety of decay modes Final states include photons and charged particles and require particle identification Hermetic detector with large acceptance for charged and neutral particles In addition, sensitivity to hybrid masses up to 2.5 GeV requires 9 GeV photons which will be produced using coherent bremsstrahlung from 12 GeV electrons

19. Examples of the 12 GeV Upgrade Research • Parton Distribution Functions • Generalized Parton Distributions and Form Factors • Exotic Meson Spectroscopy: Confinement and the QCD vacuum • Nuclei at the level of quarks and gluons • Tests of Physics Beyond the Standard Model

20. The EMC Effect: Nuclear PDFs Classic Illustration: The EMC effect • Observation stunned and electrified the HEP and Nuclear communities 20 years ago • Nearly 1,000 papers have been generated….. • 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)

21. Unpacking the EMC effect • With 12 GeV, we have a variety of tools to unravel the EMC effect: • Parton model ideas are valid over fairly wide kinematic range • High luminosity • High polarization • New experiments, including several major programs: • Precision study of A-dependence; x>1; valence vs. sea • g1A(x) “Polarized EMC effect” – influence of nucleus on spin • Flavor-tagged polarized structure functions uA(xA) and dA(xA) • x dependence of axial-vector current in nuclei (can study via parity violation) • Nucleon-tagged structure functions from 2H and 3He • Study x-dependence of exclusive channels on light nuclei, sum up to EMC

22. Examples of the 12 GeV Upgrade Research • Parton Distribution Functions • Generalized Parton Distributions and Form Factors • Exotic Meson Spectroscopy: Confinement and the QCD vacuum • Nuclei at the level of quarks and gluons • Tests of Physics Beyond the Standard Model

23. PV DIS at 11 GeV with an LD2 target For an isoscalar target like 2H, the structure functions largely cancel in the ratio: (Q2 >> 1 GeV2 , W2 >> 4 GeV2, x ~ 0.3-0.5) • Must measure APV to 0.5% fractional accuracy! • Luminosity and beam quality available at JLab e- e- Z* * X N • 6 GeV experiment will launch PV DIS measurements at JLab (2009) • 11 GeV experiment will allow tight control of systematic errors • Important constraint should LHC observe an anomaly

24. Precision High-x Physics with PV DIS For hydrogen 1H: 1% APV measurements Longstanding issue: d/u as x1 • Allows d/u measurement on a single proton! Charge Symmetry Violation (CSV) at High x: clean observation possible? Londergan & Thomas • Direct observation of CSV at parton level! • Implications for high-energy collider pdfs • Could explain large portion of the NuTeV anomaly Needs 1% measurement of APV at x ~ 0.75 Global fits allow 3 times larger effects

25. A Vision for Precision PV DIS Physics • Hydrogen and Deuterium targets • Better than 2% errors (unlikely that any effect is larger than 10%) • x-range 0.25-0.75 • W2 well over 4 GeV2 • Q2 range a factor of 2 for each x (except x~0.75) • Moderate running times • CW 90 µA at 11 GeV • 40 cm liquid H2 and D2 targets • Luminosity > 1038/cm2/s • solid angle > 200 msr • count at 100 kHz • on-line pion rejection of 102 to 103 Goal: Form a collaboration, start real design and simulations, after successful pitch to US community at the ongoing Nuclear Physics Long Range Plan

26. Future Possibilities (Purely Leptonic) JLab e2e @ 12 GeV Møller at 11 GeV at JLab sin2W to ± 0.00025! ee ~ 25 TeV reach e.g. Z’ reach ~ 2.5 TeV Higher luminosity and acceptance • Comparable to single Z-pole measurement: shed light on 4 disagreement • Best low-energy measurement until ILC or -Factory • Could be launched ~ 2015 Kurylov, Ramsey-Musolf, Su Does Supersymmetry (SUSY) provide a candidate for dark matter? • Neutralino is stable if baryon (B) and lepton (L) numbers are conserved • In RPV B and L need not be conserved: neutralino decay

27. Upgrade magnets and power supplies CHL-2 Enhance equipment in existing halls Add new hall 12 11 6 GeV CEBAF

28. Hall B - CLAS12 Forward Calorimeter Preshower Calorimeter Forward Cerenkov (LTCC) Forward Time-of-Flight Detectors Forward Drift Chambers Superconducting Torus Magnet New TOF Layer Inner Cerenkov (HTCC) Central Detector Beamline Instrumentation * Reused detectors from CLAS Inner Calorimeter

29. Hall C - Side View of SHMS Design

30. Hall D - Coherent Bremsstrahlung Incoherent & coherent spectrum 40% polarization in peak tagged (0.1% resolution) 12 GeV electron beam flux This technique provides requisite energy, flux and linear polarization photons out collimated electrons in spectrometer (two magnets) diamond crystal photon energy (GeV)

31. Hall D - GluEx Detector Hermetic detection of charged and neutral particles Tagger Spectrometer (Upstream)

32. 12 GeV Upgrade: Project Schedule • 2004-2005 Conceptual Design (CDR) • 2004-2008 Research and Development (R&D) • 2006 Advanced Conceptual Design (ACD) • 2007-2009 Project Engineering & Design (PED) • 2008-2009 Long Lead Procurement • 2009-2013 Construction • 2012-2014 Pre-Ops (beam commissioning and first production data) • JLab Upgrade only present construction project in DOE-NP • First 11 GeV data expected in 2013 • However, plans for next upgrade already being developed now

33. Understand visible matter in terms of quarks and gluons • Explore the new QCD frontier: • strong color fields in nuclei • How do the gluons contribute to the structure of the nucleon? • How do the gluons contribute to the structure of the nucleus? • What are the properties of high density gluonic matter? • How do fast quarks or gluons interact as they traverse nuclear matter? • 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 is the spatial distribution of • the gluons and sea quarks in the nucleon? • How do hadronic final states form in QCD?

34. The Gluon Contribution to the Proton Spin Projected data on g/g with an EIC, via  + p  D0 + X K- + π+ Advantage: measurements directly at fixed Q2 ~ 10 GeV2 scale! RHIC-Spin • Uncertainties in xg smaller than 0.01 • Measure 90% of G (@ Q2 = 10 GeV2) Access to g/g is also possible from the g1p measurements through the QCD evolution, and from di-jet measurements

35. ELIC ring-ring design ElectronCooling 30-225 GeV protons 30-100 GeV/N ions Snake √s = 20 - 90 GeV IR IR Snake 3-9 GeV electrons 3-9 GeV positrons • “Figure-8” lepton/ion rings to ensure spin preservation and easy spin manipulation • Peak luminosity up to ~1035 cm-2s-1 through short ion bunches, low β*, and high rep rate (crab crossing) • Four interaction regions with  3m “element-free” straight sections • SRF ion linac concept for all ions ~ FRIB • 12 GeV CEBAF accelerator, with present JLab DC polarized electron gun, serves as injector to the electron ring.

36. LRP Recommendations • We recommend the completion of the 12 GeV Upgrade at Jefferson Lab. The Upgrade will enable new insights into the structure of the nucleon, the transition between the hadronic and quark/gluon descriptions of nuclei, and the nature of confinement. • We recommend the construction of the Facility for Rare Isotope Beams, FRIB, a world-leading facility for the study of nuclear structure, reactions and astrophysics. Experiments with the new isotopes produced at FRIB will lead to a comprehensive description of nuclei, elucidate the origin of the elements in the cosmos, provide an understanding of matter in the crust of neutron stars, and establish the scientific foundation for innovative applications of nuclear science to society. • We recommend a targeted program of experiments to investigate neutrino properties and fundamental symmetries. These experiments aim to discover the nature of the neutrino, yet unseen violations of time-reversal symmetry, and other key ingredients of the new standard model of fundamental interactions. Construction of a Deep Underground Science and Engineering Laboratory is vital to US leadership in core aspects of this initiative. • The experiments at the Relativistic Heavy Ion Collider have discovered a new state of matter at extreme temperature and density - a quark-gluon plasma that exhibits unexpected, almost perfect liquid dynamical behavior. We recommend implementation of the RHIC II luminosity upgrade, together with detector improvements, to determine the properties of this new state of matter.

37. LRP Recommendation #1 We recommend the completion of the 12 GeV Upgrade at Jefferson Lab. The Upgrade will enable new insights into the structure of the nucleon, the transition between the hadronic and quark/gluon descriptions of nuclei, and the nature of confinement. A fundamental challenge for modern nuclear physics is to understand the structure and interactions of nucleons and nuclei in terms of quantum chromodynamics. Jefferson Lab’s unique electron microscope has given the US leadership in addressing this challenge. Its first decade of research has already provided key insights into the structure of nucleons and the dynamics of finite nuclei. Doubling the energy of this microscope will enable three-dimensional imaging of the nucleon, revealing hidden aspects of its internal dynamics. It will complete our understanding of the transition between the hadronic and quark/gluon descriptions of nuclei, and test definitively the existence of exotic hadrons, long-predicted by QCD as arising from quark confinement. Through the use of parity violation, it will provide low-energy probes of physics beyond the Standard Model, complementing anticipated measurements at the highest accessible energy scales.

38. Summary of Future Research at JLab • The Upgrade to 12 GeV at JLab is well underway (preparing for CD-2 review this month!) with strong support from the Nuclear Physics LRP • It will allow ground-breaking studies of • the structure of the nucleon • exotic mesons and the origin of confinement • the QCD basis of nuclear structure • the Standard Model at the multi-TeV scale • All requiring the use of highly polarized beams (and/or targets) • The schedule of the LQCD program at JLab is commensurate with the physics goals of the 12 GeV Upgrade • Design studies at JLab have led to a promising design of an electron-ion collider (ELIC) • a luminosity of up to ~1035 cm-2 s-1 • at a center-of-mass energy between 20 and 90 GeV • for collisions between polarized electrons/positrons and ions (A≤208)