The Long Range Plan for QCD Peter Jacobs, LBNL

2 The Long Range Plan for QCD DOE/NSF Charge to NSAC

3 The Long Range Plan for QCD DOE/NSF Charge to NSAC cont’d a.k.a. American Competitiveness Initiative (2006 State of the Union Address)

4 The Long Range Plan for QCD NSAC charge to DNP: Town Meetings

5 The Long Range Plan for QCD QCD and Hadron Physics S. Capstick L. Cardman, A.Deshpande, X. Ji, C.Keppel, C. Meyer, Z. Meziani, J. Negele, J.-C. Peng Phases of QCD Matter P. Jacobs, D. Kharzeev, B. Mueller, J. Nagle, K. Rajagopal, S. Vigdor

6 The Long Range Plan for QCD Background White Papers RHIC II Electron Ion Collider RHIC Theory Upgrade LHC: –ATLAS Heavy Ions –CMS Heavy Ions –ALICE-US –LHeC (new proposal for electron ring in LHC tunnel) Accelerator R&D Posted at:

7 The Long Range Plan for QCD Summary of RHIC thus far The hottest (T~ MeV) densest (jet quenching:  i ~30-60  0 ) Matter (thermal yields) ever studied in the laboratory Flows (large elliptic flow) as a (nearly) perfect fluid with systematic patterns consistent with quark degrees of freedom (valence quark scaling) and a viscosity to entropy-density ratio lower (?) than any other known fluid, with a value near (?) a conjectured quantum bound  /s~2-3 x 1/4  W. Zajc

8 The Long Range Plan for QCD So are we done? U. Heinz

9 The Long Range Plan for QCD U. Heinz

10 The Long Range Plan for QCD AdS/CFT: a startling development from string theory Conjecture: hidden within every non-Abelian gauge theory, even within the weak and strong nuclear interactions, is a theory of quantum gravity. (Horowitz and Polchinski, gr-qc/ )gr-qc/ Has stimulated new directions in theory (e.g. lower bound on  /s arises from basic quantum mechanics but was first derived in string theory) Potential connections to RHIC/LHC heavy ion physics: shear viscosity, jet quenching, J/  suppression,… But speculative at present: no testable calculations or predictions yet Zajc, Kaplan

11 The Long Range Plan for QCD The interplay of RHIC and LHC Together, RHIC and LHC span an energy range of more than 3 units of magnitude (say 50 GeV TeV). How do the properties of hot and dense QCD matter evolve with energy from RHIC to LHC? Don’t trust the argument, that the high-temperature phase of QCD is featureless above T c. This may be true for the energy density, but: - Measurable quantities related to 1st principle calculations, such as are likely to satisfy non-linear small-x evolution equations (similar to Q s ) - QCD measures of deviations from conformality change strongly from T c to 3T c. This may provide crucial input for fundamental theoretical approaches (e.g. string theory), which start from perturbations of a conformal framework I advocate to identify this question now as a major scientific challenge of the next decade, to be explored in an interplay of RHIC and LHC. Consequence: RHIC luminosity upgrade also motivated by increasing kinematical reach for comparison with LHC. U. Wiedemann

12 The Long Range Plan for QCD Big Questions for an e+p/A collider Vogelsang, Ent, Kovchegov, Surrow,… EIC: polarized e+p, unpolarized e+A Broad theme: precision studies of emergent features of QCD What are the momentum distributions of quarks, anti-quarks and gluons in the nucleon? What symmetries (flavor, isospin) hold or are broken in the nucleon? How are quarks and gluons distributed spatially in the nucleon? What is the nature of glue at high density? –How do strong fields appear in hadronic or nuclear wave functions at high energies? –What are the appropriate degrees of freedom? –How do they respond to external probes or scattering? –Is this response universal (ep, pp, eA, pA, AA)?

13 The Long Range Plan for QCD Proposed EIC Designs eRHIC L = 2.6x10 33 cm -2 s -1 E cm = 140 GeV Luminosities are for e-p collisions LHeC L = 1.1x10 33 cm -2 s -1 E cm = 1.4 TeV ELIC (JLab) L = 7.7x10 34 cm -2 s -1 E cm = 65 GeV L = 0.47x10 33 cm -2 s -1 E cm = 100 GeV L. Merminga

14 The Long Range Plan for QCD Summary of EIC candidates Summary of EIC candidates eRHIC ERLeRHIC R-R ELICLHeC E CM [GeV] Speciesp,.., 238 U positrons p,.., 238 U positrons p,.., 40 Ca positrons p, positrons Polarization p,D, 3 He,e -,e + yes Not planned Number of IR’s Up to 41 (2*)41 IR free space [m] ±5±1±2 (up to ±3)1.2 L peak [cm -2 sec -1 ] 2.6x10 33 **0.47x x x10 33 *Requires second ring **one IR L. Merminga

15 The Long Range Plan for QCD Physics reach of eRHIC: F 2 (x,Q 2 ) sea quarks generated by glue F 2 will be one of the first measurements at EIC nDS, EKS, FGS: pQCD models with different amounts of shadowing EIC will distinguish between pQCD and saturation model predictions Th. Ullrich

16 The Long Range Plan for QCD F L at eRHIC: direct measurement of glue Q 2 /xs = y Needs  s scan EIC will measure G(x,Q 2 ) precisely EIC: (10+100) GeV  Ldt = 2/A fb -1 Th. Ullrich

17 The Long Range Plan for QCD Phases of QCD: Recommendation #1 1. Our central goal is a dramatic advance in our understanding of QCD Matter, through quantitative comparison of theory and experiment to determine the properties of the strongly interacting Quark-Gluon Plasma discovered in the initial phase of RHIC operations, and through further exploration of the QCD phase diagram at non-zero baryon density where a critical point has been predicted. The essential requirements for the success of this scientific program are therefore our highest priorities: Effective utilization of the RHIC facility and completion of the ongoing detector upgrade program; The RHIC II luminosity upgrade, which will enable quantitative study of rare processes; Strong support for the ongoing theoretical studies of QCD matter, including finite temperature and finite baryon density lattice QCD studies and phenomenological modeling, and an increase of funding to support new initiatives enabled by experimental and theoretical breakthroughs.

18 The Long Range Plan for QCD Phases of QCD Recommendation #2: LHC 2. We strongly recommend significant and timely participation of U.S. groups in the LHC heavy ion program, which will study QCD matter at the highest energy densities and temperatures available in the laboratory. This program will test and extend the insights reached in the RHIC program, and has the potential to make important new discoveries about QCD Matter.

19 The Long Range Plan for QCD Phases of QCD Recommendation #3: EIC Same EIC bullet will appear in “Phases of QCD Matter” and “Hadronic Physics” Summary White Papers (minor modifications not yet finalized) 3. An Electron-Ion Collider (EIC) facility is the highest priority of the QCD community for new construction after the JLab 12 GeV and the RHIC II luminosity upgrades. EIC will address compelling physics questions essential for understanding the fundamental structure of matter: Precision imaging of sea-quarks and gluons to determine the full spin, flavor and spatial structure of the nucleon; Definitive study of the universal nature of strong gluon fields manifest in nuclei. This goal requires that R&D resources be allocated for expeditious development of collider and experimental design.

20 The Long Range Plan for QCD Further recommendations Still to be written: 4. Common theory bullet (the bullet is common, not the theory) 5. Education and Outreach 6. Accelerator R&D

21 The Long Range Plan for QCD What happens next? Summary White Paper from each Town Meeting, presents and justifies priorities (bullets) first draft in early March Status reports and discussion at NSAC meeting March 8-9 Status reports at Spring APS Meeting, Jacksonville, April (session U2, Monday p.m.) The smoke-filled room: Long Range Plan “Resolution Meeting”, Galveston TX, April 30-May 4