Next Generation Nuclear Physics

1. Next Generation Nuclear Physics Barbara Jacak Stony Brook April 7, 2006 QCD with nuclei as the laboratory colliders to explore the frontiers of high temperature and high density

2. QCD lab at BNL • High Temperature limit of QCD: HI collisions at RHIC • High Density limit: • electron-ion collider • reach very small x • non-perturbative QCD: • large-scale computing • resources: QCDOC +… T>200 MeV

3. QCD new phases confinement p-spin structure low x color glass High T,r QCD RHIC eRHIC RHIC upgrades DiscoveryExploration Precision A Unique Evolution

4. At high temperature and density: force is screened by produced color-charges expect transition to plasma of (free?) quarks and gluons + +… QCD phase transition at high T Color charge of gluons  self-interaction • theory is non-abelian confinement of quarks in hadrons at large distance: asymptotic freedom

5. STAR 4 complementary experiments at RHIC

6. Kolb, et al We have found really surprising stuff! • Pressure built up very rapidly during ion collisions at RHIC • large collective flow • hydrodynamics works w/low viscosity • interaction s large, fast thermalization • viscosity small • huge energy loss in fast quarks traversing medium • energy, gluon density large • medium is opaque • 3x higher baryon yield than p+p PHENIX Not the expected ideal gas!!

7. Hatsuda, et al. Lattice QCD shows qq resonant states at T > Tc, also implying high interaction cross sections fast equilibration, flow, opacity – how? Molnar parton cascade using free q,g scattering cross sections doesn’t work! need s x50 in medium

8. see something like this in EM plasma! S. Ichimaru strong coupling viscosity coupling = <PE>/<KE>

9. e± from charm show non-zero flow thermalization with the light quarks? not so easy to do! do heavy quarks also lose energy and flow? large mass → produced early sets scale for interaction w/QGP seems so, but cannot be all by radiating gluons

10. so… • How do we study the plasma physics of this stuff? • hint: • how are electromagnetic (normal) plasmas studied?

11. Plasma properties studied by plasma physicists • density and opacity seen to be high at RHIC • transport properties of the plasma • electrical and thermal conductivity • hydrodynamic expansion, shock propagation, diffusion • waves in plasma and dispersion relation • plasma oscillations and instabilities • screening length • radiation (temperature, dynamics, bound states…) • blackbody radiation from plasma • bremsstrahlung • collisions and recombination in the plasma

12. So, here’s a plan • Upgrade RHIC detectors • rare and/or high background probes of plasma • QGP plasma a “filter” for fragmentation, confinement • Increase RHIC luminosity • hard probes cross sections small at √s=200 GeV • scan beam energy, size in lifetime of a grad student! • x40 compared to baseline (x10 by electron cooling) • Add electron accelerator (either ring or linac) • reach very high gluon densities - saturation? • probe with DIS • study role of quarks, gluons in nucleon spin structure • reach very low-x, with high luminosity

13. signal electron Cherenkov blobs e- partner positron needed for rejection e+ qpair opening angle • Jet tomography (jet-jet and g-jet) → plasma transport correlations of ≥ 2 particles from jets traversing QGP g-jet correlations; g fixes jet energy identify the fragments for hadronization, charm e-loss upgrade PID(STAR), coverage(PHENIX) & luminosity! Detector upgrades to address key measurements • Electromagnetic radiation → plasma temperature photon detection by CsI-coated triple GEMs will be installed in PHENIX in 2007 e+e- pair continuum background:  e+ e - po   e+ e -

14. X D • Quarkonia • need luminosity! Au Au D B J/ K p X e e RHIC (1.5 nb-1)RHIC upgrade (30 nb-1) J/y (y’) mm38,000 (1400)760,000 (28,000)   mm 35 700 major upgrades, continued • Heavy flavor (c- and b-production) add Si vertex trackers to STAR (thinned wafers) PHENIX (strips, pixels)

15. Forward Silicon Tracker Inner Silicon Tracker Heavy Flavor Tracker W-Physics upgrades for q,qbar spin contribution • STAR: Tracking Upgrade • R&D ongoing R2 R3 R1 • PHENIX: muon trigger • funded by NSF Forward GEM Tracker

16. RHIC II RHIC Mid-Term Strategic Plan PHENIX STAR EBIS Forward Nose Cone Calorimeter Mu Trigger FMS STAR Integrated Tracking VTX PHENIX & STAR VTX upgrades TOF PID HBD Hi Rate DAQ 1000 PHENIX + STAR Data-Taking e Cooling CD-0 CD-1 CD-2 CD-3 CD-4 e-pair spectrum Jet Tomography Open Charm LHI U+U Heavy Ion Luminosity Mono-Jet SPIN F.O.M. LP4 G/G P-V W± prod. and Transversity

17. Scientific Frontiers for eRHIC • Understand nucleon structure and its spin, role of quarks & gluons in the nucleons, issues of confinement, low-x & DVCS… • Determine the role of partons in nuclei to understand confinement in nuclei • Study hadronization in nucleons & in nuclear media • Explore partonic matter under extreme conditions with e-A • Large “A” at RHIC : very high gluon densities • Saturation/Color Glass Condensate

18. EIC detector central tracking: high precision, fast Si (inner) triple-GEM (outer)

19. 5.5 1027 70-50 106 ** 7.7 Further pushing the high T limit:the LHC as a heavy ion collider Running parameters: √sNN (TeV) L0 (cm-2s-1) <L>/L0 (%) Run time (s/year) sgeom (b) Collision system 1034 * 14.0 107 0.07 pp PbPb *Lmax(ALICE) = 1031 ** Lint(ALICE) ~ 0.7 nb-1/year Other collision systems: pA, lighter ions (Sn, Kr, Ar, O) and energies

20. Solenoid magnet 0.5 T ALICE: the dedicated HI experiment • Central tracking system: • ITS • TPC • TRD • TOF • MUON Spectrometer: • absorbers • tracking stations • trigger chambers • dipole

21. ALICE Tracking Combined tracking efficiency and momentum resolution

22. Challenges for TPCs in high luminosity A+A • event pile-up • pattern recognition problem gets “interesting” • space charge • field distortion effect upon momentum reconstruction • can the compact TPC ideas be practical and efficient for the huge multiplicities of heavy ion collisions?

23. RHIC Upgrades Overview X upgrade critical for success O upgrade significantly enhances program A. Drees 4/4/05

24. d (u) W u ( d) Spin Structure of the Proton: W physics • Goal: • q andq spin structure of the nucleon • Use pp → W+X • Challenges: • nb cross section: run pp at 500 GeV with high luminosity and polarization • Reduce MHz interaction rate → few kHz event rate • Unambiguous identification of W+,W- • Detector upgrades: • PHENIX: high pT single muon trigger • STAR: tracking upgrade

25. Forward Physics Upgrades: 1<<3 • STAR: forward meson calorimeter • Proposal submitted to NSF • PHENIX: forward calorimeter • R&D ongoing

26. what is a plasma? • 4th state of matter (after solid, liquid and gas) • a plasma is: • ionized gas which is macroscopically neutral • (not neutral on scale of interparticle distance) • exhibits collective effects • interactions among charges of multiple particles • spreads charge out into characteristic (Debye) length, lD • multiple particles inside this length • they screen each other • plasma size > lD

27. Where the QCD plasma physics fits in high energy density: e > 1011 J/m3 P > 1 Mbar I > 3 X 1015W/cm2 Fields > 500 Tesla

28. is QGP a strongly coupled plasma? how does it compare to interesting EM plasmas? • Huge gluon density! • estimate G = <PE>/<KE> • using QCD coupling strength g • <PE>=g2/d d ~1/(41/3T) • <KE> ~ 3T • G ~ g2 (41/3T)/ 3T • g2 ~ 4-6 (value runs with T) for T=200 MeV plasma parameter G ~ 3  quark gluon plasma should be a strongly coupled plasma G > 1: strongly coupled, few particles inside Debye radius

29. more sophisticated • see Markus Thomas hep-ph/0503154 • getting the units right… • G = 2Cg2/4pdT • get G ~ 1.5 – 5 at T=200 MeV • NB: magnetic interaction is ~ comparable to electric interaction in a relativistic plasma • range from uncertainties in g2 and Casimirs

30. seems to be a perfect fluid (not quite sci-fi!) would like to calculate: this is hard! • A (supersymmetric) pseudo-QCD theory can be mapped to a 10-dimensional classical gravity theory on the background of black 3-branes • The calculation can be performed there as the absorption of gravitons by the brane • THE SHEAR VISCOSITY OF STRONGLY COUPLED N=4 SUPERSYMMETRIC YANG-MILLS PLASMA., G. Policastro, D.T. Son , A.O. Starinets, Phys.Rev.Lett.87:081601,2001 hep-th/0104066 • gives h = (h/4p) S known liquids, even He, are above this!

31. for strongly coupled EM plasmas • kinetic energy distribution (T) • measure electrons radiated from plasma • flow properties (turbulent and non) • particle transport via laser-induced flourescence • again study electron radiation from plasma • opacity to hard x-rays (time resolved) • thermalization time • photon absorption & ion spectrum vs. time • plasma oscillations • see density fluctuations in electron arrival times • correlations among particles • measure radiated particle pairs • crystallization • viscosity

32. STAR Preliminary (1/Ntrig)dN/d(Df) M.Miller, QM04 PHENIX preliminary dN/d(Df) 0 p/2 p p/2 p Df =+/-1.23=1.91,4.37 → cs ~ 0.33 (√0.33 in QGP, 0.2 in hadron gas) speed of sound via a density wave? g radiates energy kick particles in the plasma accelerate them along the jet

33. Jet tomography • correlations of 2, 3 (more?) particles • from jets traversing medium • g-jet correlations; g fixes jet energy • gq →gq • identify the hadrons: hadronization, charm e-loss • increase PHENIX, STAR calorimeter coverage for g • 2008-2011 • upgrade rate capabilities of data acquisition, analysis • 2007 • increased machine luminosity (2013?) cross section small, so rate is low

34. jet partners per trigger all baryons from quarks drawn from the medium p+p Npart why so many baryons at medium pT? • sensitive probe of hadronization • quark coalescence: good starting point • small production rate →sensitivity to • correlations of quarks inside the medium! • a tool to probe wakes in the plasma. correlators? • upgrade PID in STAR and PHENIX by ‘09 • increased luminosity to allow scanning collision energy, species (Au+Au, Cu+Cu compare to p+p, d+Au)

35. dileptons and photons • pT spectrum of soft g, g* reflects Tinitial • interpretation problem: • unfolding time history • of the expansion • note: fixing the EOS • for hydro is essential! • medium modification • of final vector mesons • decays of bound states? • detector upgrades will reduce decay background and allow measurement of charm background • energy & system size scans require luminosity upgrade

36. RHIC Heavy Quarkonium – a screening probe • map charmonium and bottomonium states to study competition between melting and regeneration • color screening length? Tinitial? • upgraded luminosity will allow: • measurement of Y • v2 of J/y • energy scan for J/y, screening vs. regeneration counts per year comparable to those at LHC!

37. why do we need high luminosity? • QCD analogy to hard x-ray probes in plasma physics? • for opacity studies & Thomson scattering • -> monoenergetic hard colored probe • achievable via g-jet coincidences, binned in g energy • QCD analogy to probes of screening length • J/psi suppression via screening c-cbar bound state? • very confusing at the moment! • need more theory and data • QCD analogy to plasma shots with different conditions • scan in energy and system size • measure opacity, elliptic flow, charm, g-jet

38. Heavy Quarks – open charm • precision measurements to quantify energy loss and v2 as a function of momentum • how opaque IS the medium? • relative role of gluon • radiation and collisional • energy loss • must measure charm yield • to subtract from • intermediate mass dilepton continuum • inner tracker upgrades for PHENIX and STAR needed to tag displaced vertex for clean measurement • ready by 2011

39. what sQGP plasma properties could these yield? • speed of sound via jet modifications • quark correlations in the medium • baryon formation • medium modifications of jet fragmentation • propagation of jet-induced shocks • constrain radiative vs. collisional energy loss • screening length via onium spectroscopy • T via radiated dileptons, photons • dissipation via energy flow in shocked medium • Would like to identify experimental signatures of • viscosity • Weibel instability in first 0.6 fm/c

40. Medium is opaque! look for the jet on the other side STAR PRL 90, 082302 (2003) Peripheral Au + Au Central Au + Au

41. Pedestal&flow subtracted Are back-to-back jets there in d+Au? Yes! no medium ↓ no jet quenching

42. At RHIC: J/ymm muon arm 1.2 < |y| < 2.2 measured/expected dAu mm 200 GeV/c AuAu mm 200 GeV/c CuCu mm 200 GeV/c

43. At RHIC: J/ymm muon arm 1.2 < |y| < 2.2 J/yee Central arm -0.35 < y < 0.35 dAu mm 200 GeV/c AuAu mm 200 GeV/c CuCu mm 200 GeV/c AuAu ee 200 GeV/c CuCu ee 200 GeV/c

44. At RHIC: J/ymm muon arm 1.2 < |y| < 2.2 J/yee Central arm -0.35 < y < 0.35 ! Factor ~3 suppression in central events dAu mm 200 GeV/c AuAu mm 200 GeV/c CuCu mm 200 GeV/c AuAu ee 200 GeV/c CuCu ee 200 GeV/c CuCu mm 62 GeV/c

45. At RHIC: J/ymm muon arm 1.2 < |y| < 2.2 J/yee Central arm -0.35 < y < 0.35 ! Factor ~3 suppression in central events Data show the same trend within errors for all beams and even at √s=62 GeV

46. RAA vs Npart: PHENIX and NA50 • NA50 data normalized at NA50 p+p point. • Suppression similar in the two experiments, although the collision energy is 10 times higher (200GeV in PHENIX & 17GeV in NA50)

47. What suppression should we expect? Models that were successful in describing SPS data fail to describe data at RHIC - too much suppression -

48. can get better agreement with data if add formation of “extra” J/y by coalescence of c and anti-c from the plasma caveat: not necessarily unique or correct explanation!

49. Possibility of plasma instability → anisotropy • small deBroglie wavelength q,g point sources for g fields • gluon fields obey Maxwell’s equations • add initial anisotropy and you’d expect Weibel instability • moving charged particles induce B fields • B field traps soft particles moving in A direction • trapped particle’s current reinforces trapping B field • can get exponential growth • (e.g. causes filamentation of beams) • could also happen to gluon fields early in Au+Au collision • timescale short compared to QGP lifetime • but gluon-gluon interactions may cause instability to saturate → drives system to isotropy & thermalization

50. The vision of a QCD laboratory • QCD Laboratory at BNL • A place to do e-p, e-A, p-A, p-p & A-A collisions & multiple detectors and Lattice QCD computing facility • explore • zero and high temperature QCD at limits of our knowledge • nucleon spin structure in its entirety using hadronic and leptonic probes • A. Deshpande (SBU/RBRC) & Richard Milner (MIT) the advisors for the eRHIC • B. Jacak (SBU) and John Harris (Yale) for A-A experiments in the next decade