Experimental ‘Heavy Ion Physics’ B. A. Cole and W.A. Zajc

1. Experimental ‘Heavy Ion Physics’ B. A. Cole and W.A. Zajc

2. Experimental Studies of QCD B. A. Cole and W.A. Zajc

3. Context • The past decade has revolutionized our appreciation of the strong interaction, driven by • RHIC Discoveries • Lattice QCD • Theoretical Advances • The critical role of ‘saturation’ phenomena • Strong coupling studies in AdS/CFT

4. But One Example • Comparing energy loss and p-perpendicular - broadening in perturbative QCD with strong coupling N = 4 SYM theory.Fabio Dominguez (Columbia U.) , C. Marquet (Saclay, SPhT & Columbia U.) , A.H. Mueller (Columbia U.) , Bin Wu (Peking U. & Columbia U.) , Bo-Wen Xiao (Columbia U.) . Mar 2008. 33pp. e-Print: arXiv:0803.3234 [nucl-th] • References | LaTeX(US) | LaTeX(EU) | Harvmac | BibTeX | Cited 1 time • Abstract and Postscript and PDF • Jet evolution in the N=4 SYM plasma at strong coupling.Y. Hatta (Tsukuba U., GSPAS) , E. Iancu (Saclay, SPhT) , A.H. Mueller (Columbia U.) . Mar 2008. 37pp. e-Print: arXiv:0803.2481 [hep-th] • References | LaTeX(US) | LaTeX(EU) | Harvmac | BibTeX | Cited 2 times • Abstract and Postscript and PDF • Deep inelastic scattering off a N=4 SYM plasma at strong coupling.Y. Hatta, E. Iancu (Saclay, SPhT) , A.H. Mueller (Columbia U.) . Oct 2007. 36pp. Published in JHEP 0801:063,2008. e-Print: arXiv:0710.5297 [hep-th] • References | LaTeX(US) | LaTeX(EU) | Harvmac | BibTeX | Cited 7 times • Abstract and Postscript and PDF from arXiv.org • Deep inelastic scattering at strong coupling from gauge/string duality: The Saturation line.Y. Hatta, E. Iancu (Saclay, SPhT) , A.H. Mueller (Columbia U.) . Oct 2007. 40pp. Published in JHEP 0801:026,2008. e-Print: arXiv:0710.2148 [hep-th] • References | LaTeX(US) | LaTeX(EU) | Harvmac | BibTeX | Cited 14 times • Abstract and Postscript and PDF

5. Executive Summary • The past decade has revolutionized our appreciation of the strong interaction, driven by • RHIC Discoveries • Lattice QCD • Theoretical Advances • The critical role of ‘saturation’ phenomena • Strong coupling studies in AdS/CFT • Columbia has played a leading role in all of these. • There are outstanding new experimental opportunities. • The size of our group • (Brian Cole + WAZ) is sub-optimal for pursuing those opportunities

6. Columbia Leadership • Dates back to 1974 (preQCD!) • Long interregnum: • LBNL Bevalac ~ 1976 • BNL AGS ~ 1986 • CERN SPS ~ 1986 • RHIC 2000 • (LHC) 2008-9

7. PHENIX Involvement • Major Columbia Involvement in • Design • Electronics • Data Acquisition • Leadership • Science of this international collaboration • Faculty: B. Cole, WAZ • Research Scientist: C.Y. ChiE. Mannel • Post-docs: W. Holzmann, N. Grau, D. Winter • Graduate Students: A. Angerami, T. Engelmore, J. Hanks, Y. Lai, E. Vazquez, (Yujiao Chen)

8. PHENIX Results • First RHIC data taken in 2000 • Since then • 41 PRL’s • 18 Phys. Rev. C’s • 5 Phys. Rev. D’s • 2 Phys. Lett. B’s • 1 Nucl. Phys. A • At least two of these within striking distance of SPIRES ‘renowned’ papers (500+ citations) • Columbia played major role in most of the major papers

9. Scientific American May-06

10. New Opportunity: Pb+Pb @ LHC w/ ATLAS Brian Cole, leader of US-ATLAS Heavy Ion Program

11. ATLAS (‘heavy ion’) Results • First data taken in 2009? • After then • a PRL’s • b Phys. Rev. C’s • c Phys. Rev. D’s • dd J. Phys. G’s • ee (other open access venues) • Certain to (eventually) become ‘renowned’ papers (500+ citations) • Columbia will play major role in all of the major papers • IF we can address concerns about group size

12. A Renowned ATLAS Paper To Be • “Testing AdS/CFT deviations from pQCD heavy quark energy loss with Pb+Pb at LHC ”,W.A. Horowitz, M. Gyulassy e-Print: arXiv:0706.2336 • A fundamentaltest of theapplicabilityof string theorymethods tocalculateenergy lossin thermalQCD matter

13. Two Experiments on Two Continents • With two faculty

14. Hmmm Norman Al

15. Two Experiments on Two Continents • Faculty • B. Cole • WAZ (DNP) • Research Scientist: • C.Y. Chi • E. Mannel • Post-docs: • W. Holzmann • N. Grau • D. Winter • Graduate Students: • A. Angerami • T. Engelmore • J. Hanks • Y. Lai • E. Vazquez • (Yujiao Chen) PHENIX ATLAS

16. Our Competition • MIT • RHIC Spin: 2 faculty • LHC Heavy Ions: 3 faculty + 1 Senior Research Scientist • Stony Brook • RHIC Spin: 1 faculty • RHIC Heavy Ions: 3 faculty • (another hire likely)

17. How Perfect is “Perfect” • All “realistic” hydrodynamic calculations for RHIC fluids to date have assumed “perfect fluid” zero viscosityh • But- • there is a (new) (conjectured) quantum limit: • Where do “ordinary” fluids sit wrt this limit? • RHIC “fluid” mightbe at ~1 on this scale (!) (4p) T=1012 K

18. RHIC Future • Endorsed in “A Long Range Plan for Nuclear Physics” • 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. • Quantifythe properties of this “near-perfect” fluid • Heavy-flavor with mQ/T >> 1 a very valuable observable • Search for “critical end point” bylowering RHIC energy • (Major program at GSI-FAIR 2015+)

19. Future NP Planning • From the U.S “A Long Range Plan for Nuclear Physics”: • An Electron-Ion Collider (EIC) with polarized beams has been embraced by the U.S. nuclear science community as embodying the vision for reaching the next QCD frontier. EIC would provide unique capabilities for the study of QCD well beyond those available at existing facilities worldwide and complementary to those planned for the next generation of accelerators in Europe and Asia. In support of this new direction: • We recommend the allocation of resources to develop accelerator and detector technology necessary to lay the foundation for a polarized Electron Ion Collider. The EIC would explore the new QCD frontier of strong color fields in nuclei and precisely image the gluons in the proton. • From the OECD Global Forum- two projects identified as ‘potentially global’ • EURISOL – a multi-MW ISOL facility • ‘Electron-Ion Collider’

20. eRHIC and/or LHeC • Planning wellunderway for bothfacilities • A natural extension of both RHIC spin and QCD matter studies

21. Fundamental Fields in Nuclei • Nucleus increases saturation momentum scaleQS2 ~ (A/x)1/3 • Occupation numbers ~ 1 / aS(QS) > 1 • This is the condition for ~ classical fields: • That is: • Quasi-classical states of the gluon field may be explored at low x in a nucleus • Exploration tools: • Near-term: d+A collisions (RHIC  RHIC II) • Long-term: Electron-ion Collider • Goal: • To understandthe wave-functionof a heavy nucleus

22. Gluon recombination @ LHeC ● (Slide from J. Dainton) epsaturation Q2 ≤ 5 GeV2 eAsaturation Q2 ≤ 20 GeV2 ●LHeC “nails” saturation

23. Summary • A new state of matter has been discovered at RHIC • Its properties represent a paradigm shift re QGP • No “free roaming” quarks and gluons • Precisely the opposite- an essentially perfect liquid • Appears to be deep (fundamental?) connections between • Thermal gauge theories (QCD) • Stringy gravity in a higher-dimensional spacetime • Extraordinary opportunities for future experimental study • QGP studies at RHIC and LHC • Origin of nucleon spin • Saturation effects in gluonic “matter” • Our effort would be greatly aided by a new (junior) appointment in the broad field of experimental study of “QCD matter”

24. Back-Up

25. Starter eRHIC • Center of Mass of the highest energy polarized DIS was 17 GeV. • With 1-3 GeV e-beam variation, and 50-250 GeV polarized proton beam variation, eRHIC-Stage-1 will scan 14-50 GeV in Center of Mass. • Up to 34 GeV in e-A Center of Mass. Target fragments of neither the polarized protons nor the nuclei have been studied in detail so far: most often due to the fact that target have been solid state materials and the target fragments were lost in them. • The final eRHIC will range from about 40 GeV to 100 GeV in CM with about 10 GeV electron beams. Data from these two stages of eRHIC will scan large Q2 ranges allowing very nice measurements of F_L (HERA did not do such a great job on this) and will allow many spin measurements which require large Q2 arms. And they will be at about 100 times higher luminosity than HERA. Many of the diffractive and exclusive measurements (DCVS-type) will be possible, which were not possible at HERA.

27. The Basic Results

28. To Summarize The hottest densest matter ever studied in the laboratory flows absorbs energy as a (nearly) perfect fluid Not as an ideal gas of free quarks and gluons ! T ~ 200- 400 MeV ei ~ 30-60 eo (thermal yields) large “elliptic” flow jet quenching, Mach cones

29. RHIC Success