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Introduction and Welcome AdS/CFT Intersects Nuclear Beams at Columbia W.A. Zajc

Introduction and Welcome AdS/CFT Intersects Nuclear Beams at Columbia W.A. Zajc Columbia University. RHIC Perspectives W.A. Zajc Columbia University. RHIC Perspectives W.A. Zajc Columbia University. Outline of My Talk. Really, It’s A Meta-Talk.

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Introduction and Welcome AdS/CFT Intersects Nuclear Beams at Columbia W.A. Zajc

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  1. Introductionand Welcome AdS/CFT Intersects Nuclear Beams at Columbia W.A. Zajc Columbia University W.A. Zajc

  2. RHIC Perspectives W.A. Zajc Columbia University RHIC Perspectives W.A. Zajc Columbia University W.A. Zajc

  3. Outline of My Talk W.A. Zajc

  4. Really, It’s A Meta-Talk Two major discoveries:FlowJet quenching Introduction, Motivation,Definition of terms up to here W.A. Zajc

  5. Really, It’s A Meta-Talk Flow, v2 scaling with nq W.A. Zajc

  6. Really, It’s A Meta-Talk Jet quenching,away-side disappearance,direct photons Mach cones, re-appearance of the away side W.A. Zajc

  7. Really, It’s A Meta-Talk Perfect liquid,KSS bound as QM resultViscosity primer W.A. Zajc

  8. Really, It’s A Meta-Talk The dénouement!AdS/CFT connectionh/s values W.A. Zajc

  9. The Primacy of QCD • While the (conjectured) boundis a purely quantum mechanical result . . . • It was derived in and motivated by the Anti-de Sitter space / Conformal Field Theory correspondence • Weak form: • “Four-dimensional N=4 supersymmetric SU(Nc) gauge theory is equivalent to IIB string theory with AdS5 x S5 boundary conditions.”( The Large N limit of superconformal field theories and supergravity, J. Maldacena, Adv. Theor. Math. Phys. 2, 231, 1998 hep-th/9711200 ) • Strong form: • “Hidden within every non-Abelian gauge theory, even within the weak and strong nuclear interactions, is a theory of quantum gravity.”( Gauge/gravity duality, G.T. Horowitz and J. Polchinski, gr-qc/0602037 ) • Strongest form: Only with QCD can we explore experimentally these fascinating connections over the full range of the coupling constant to study QGP  Quantum Gauge Phluid W.A. Zajc

  10. The (Assumed) Connection • Exploit Maldacena’s “D-dimensional strongly coupled gauge theory  (D+1)-dimensional stringy gravity” • Thermalize with massive black brane • Calculate viscosity h= “Area”/16pG • Normalize by entropy (density) s = “Area” / 4G • Dividing out the infinite “areas” : • Conjectured to be a lower bound “for all relativistic quantum field theories at finite temperature and zero chemical potential”. • See “Viscosity in strongly interacting quantum field theories from black hole physics”, P. Kovtun, D.T. Son, A.O. Starinets, Phys.Rev.Lett.94:111601, 2005, hep-th/0405231 hmn Am Infinite “Area” ! An W.A. Zajc

  11. New Dimensions in RHIC Physics • “The stress tensor of a quark moving through N=4 thermal plasma”, J.J. Friess et al., hep-th/0607022 Jet modifications from wake field Our 4-d world The stuff formerly known as QGP Heavy quark moving through the medium String theorist’s 5+5-d world Energy loss from string drag W.A. Zajc

  12. Measuring h/s • Damping (flow, fluctuations, heavy quark motion) ~ h/s • FLOW: Has the QCD Critical Point Been Signaled by Observations at RHIC?,R. Lacey et al., Phys.Rev.Lett.98:092301,2007 (nucl-ex/0609025) • The Centrality dependence of Elliptic flow, the Hydrodynamic Limit, and the Viscosity of Hot QCD, H.-J. Drescher et al., (arXiv:0704.3553) • FLUCTUATIONS: Measuring Shear Viscosity Using Transverse Momentum Correlations in Relativistic Nuclear Collisions, S. Gavin and M. Abdel-Aziz, Phys.Rev.Lett.97:162302,2006 (nucl-th/0606061) • DRAG, FLOW: Energy Loss and Flow of Heavy Quarks in Au+Au Collisions at √sNN = 200 GeV (PHENIX Collaboration), A. Adare et al., to appear in Phys. Rev. Lett. (nucl-ex/0611018) CHARM! W.A. Zajc

  13. Has the QCD Critical Point Been Signaled by Observations at RHIC?,R. Lacey et al., Phys.Rev.Lett.98:092301,2007 (nucl-ex/0609025) Fit v2 ~I1(w)/I0(w); w = mT/2T • Signature: FLOW • Calculation: • Payoff Plot: On-shell transport model for gluons, Z. Xu and C. Greiner, hep-ph/0406278. PHENIX v2/e data (nucl-ex/0608033) compared to R.S. Bhalerao et al. (nucl-th/0508009) W.A. Zajc

  14. Measuring Shear Viscosity Using Transverse Momentum Correlations in Relativistic Nuclear Collisions, S. Gavin and M. Abdel-Aziz, Phys.Rev.Lett.97:162302,2006 (nucl-th/0606061) Diffusion eq. for fluctuations g • Signature: FLUCTUATIONS • Calculation: • Payoff Plot: Difference in correlation widths for central and peripheral collisions Compare to STAR data on centrality dependence of rapidity width s of pT fluctuations W.A. Zajc

  15. The Centrality dependence of Elliptic flow, the Hydrodynamic Limit, and the Viscosity of Hot QCD, H.-J. Drescher et al., (arXiv:0704.3553) • Signature: FLOW • Calculation: • Payoff Plot: Knudsen number K Decrease in flow due to finite size Fits to PHOBOS v2 data to determine s for Glauber and CGC initial conditions W.A. Zajc

  16. Energy Loss and Flow of Heavy Quarks in Au+Au Collisions at √sNN = 200 GeV (PHENIX Collaboration), A. Adare et al., Phys. Rev. Lett. 98:172301,2007(nucl-ex/0611018) • Signature: FLOW, ENERGY LOSS • Calculation: • Payoff Plot: Rapp and van Hees Phys.Rev.C71:034907,2005, to fit both PHENIX v2(e) and RAA(e) Moore and Teaney Phys.Rev.C71:064904,2005 (perturbative, argue ~valid non-perturbatively) W.A. Zajc

  17. (Some) Things I’d Like To Know • Are there better ways to extract h/s ? • Can these existing estimates be improved ? • (In particular, can systematic errors be understood?) • All of these methods rely on e+P = Ts . • How does this change in the presence of a conserved charge ? • In ordinary fluids, h/s has a pronounced minimum near the critical point. • Can AdS/CFT say anything about this for gauge fluids? W.A. Zajc

  18. (More) Things I’d Like To Know • Are AdS/CFT predictions falsifiable ? • What if Song and Heinz h/s < 1/4p is correct? • Suppression of elliptic flow in a minimally viscous quark-gluon plasma, H. Song and U. Heinz, arXiv:0709.0742v1 . • What if Mach cone angles different from data ? • What if 1/√g not seen in J/Y suppression ? • What data can best constrain initial conditions? • (Will we ever be able to eliminate this source of ambiguity between Glauber, CGC, … ?) • Are there AdS/CFT setups to do elliptic flow dynamically? • Can they say anything about the observed scaling ? W.A. Zajc

  19. ~ The “Flow” Is Perfect • The “fine structure” v2(pT) for different mass particles shows good agreement with ideal (“perfect fluid”) hydrodynamics • Roughly: ∂nTmn =0  Work-energy theorem  P d(vol) = DEK mT – m0  DKET W.A. Zajc

  20. The “Flow” Knows Quarks • The “fine structure” v2(pT) for different mass particles shows good agreement with ideal (“perfect fluid”) hydrodynamics • Scaling flow parameters by quark content nq resolves meson-baryon separation of final state hadrons baryons mesons W.A. Zajc

  21. (More) Things I’d Like To Know • What does flow scaling tell us about degrees of freedom? • Hadronic Modes and Quark Properties in the Quark-Gluon Plasma,M. Mannarelli and R. Rapp, arXiv:hep-ph/0505080v2 :m ~ 150 MeV , G ~ 200 MeV . • Is any form of quasiparticle consistent with KSS bound? • All(?) AdS/CFT calculations find drag ~ √l = √g2NC . • What is this telling us about the degrees of freedom ? • Is there a unique prescription for fixing coupling ? • Is there well-controlled expansion away from ‘t Hooft limit? • Calibrate it with lattice ‘data’ ? • ASIDE: Those who most often pronounce “AdS/CFT is useless because the coupling doesn’t run” are those most likely to do calculations with as = 0.5 . W.A. Zajc

  22. (Big ) Things I’d Like To Know • Can one start from confining, chiral Sakai-Sugimoto and push it through a phase transition ? • Hod tells us t > 1 / p T. • Universal Bound on Dynamical Relaxation Times and Black-Hole Quasinormal Ringing, S. Hod, arXiv:gr-qc/0611004v1 • Can AdS/CFT address this ? • What does it mean to have a gravity dual ? • In particular, how do I find it ? • What is the impact of the KSS conjecture on other fields ? W.A. Zajc

  23. What Follows is the Un-Meta-Talk… W.A. Zajc

  24. Working Title: The Fluid Nature of QGP • From the Oxford English Dictionary: 1) Primary definition: (adj.) fluid :"Having the property of flowing; consisting of particles that move freely among themselves, so as to give way before the slightest pressure. (A general term including both gaseous and liquid substances.)” 2) Secondary definition: (adj.)"Flowing or moving readily; not solid or rigid; not fixed, firm, or stable.” • SUMMARY: Followinga) a discovery period, during which time our understanding of “quark-gluon plasma” was fluid(2), and b) a paradigm shift,we are now developing a solid understanding of the extraordinary fluid(1) produced at RHIC. W.A. Zajc

  25. Expectations circa 2000 RHIC would create a quark-gluon plasma;a “gas” of weakly interacting quarks and gluons As encoded in the Nuclear Physics Wall Chart, http://www.lbl.gov/abc/wallchart/ W.A. Zajc

  26. The Plan circa 2000 • Use RHIC’s unprecedented capabilities • Large √s  • Access to reliable pQCD probes • Clear separation of valence baryon number and glue • To provide definitive experimental evidence for/against Quark Gluon Plasma (QGP) • Polarized p+p collisions • Two small detectors, two large detectors • Complementary capabilities • Small detectors envisioned to have 3-5 year lifetime • Large detectors ~ facilities • Major capital investments • Longer lifetimes • Potential for upgrades in response to discoveries See earlier talk by M. Grosse Perdekamp W.A. Zajc

  27. STAR RHIC and Its Experiments W.A. Zajc

  28. Since Then… • Accelerator complex • Routine operation at 2-4 x design luminosity (Au+Au) • Extraordinary variety of operational modes • Species: Au+Au, d+Au, Cu+Cu, p+p • Energies: 22 GeV (Au+Au, Cu+Cu, p), 56 GeV (Au+Au), 62 GeV (Au+Au,Cu+Cu, p+p) , 130 GeV (Au+Au), 200 GeV (Au+Au, Cu+Cu, d+Au, p+p), 410 GeV (p), 500 GeV (p) • Experiments: • Worked ! • Science • >160 refereed publications, among them > 90 PRL’s • Major discoveries • Future • Demonstrated ability to upgrade • Key science questions identified • Accelerator and experimental upgrade program underway to perform that science W.A. Zajc

  29. 2. Initial State Hydrodynamic flow from initial spatial asymmetries • Final State Yields of produced particles Thermalization, Hadrochemistry 3. Probes of dense matter Approach Will present sample of results from various points of the collision process: W.A. Zajc

  30. “Central” “Peripheral” Reaction Plane Assertion • In these complicated events, we have (a posteriori ) control over the event geometry: • Degree of overlap • Orientation with respect to overlap W.A. Zajc

  31. Language • We all have in common basic nuclear properties • A, Z … • But specific to heavy ion physics • v2 • RAA • T • mB • h • s Fourier coefficient of azimuthal anisotropies  “flow” 1 if yield = perturbative value from initial parton-parton flux Temperature (MeV) Baryon chemical potential (MeV) ~ net baryon density Viscosity ( MeV 3) Entropy density ( MeV 3) ~ “particle” density W.A. Zajc

  32. Final State Yields of produced particles Thermalization, Hadrochemistry Final State Does the huge abundance of final state particles reflect a thermal distribution?: Consistent with thermal production T ~ 170 MeV , mB ~ 30 MeV W.A. Zajc

  33. RHIC’s Two Major Discoveries • Discovery of strong “elliptic” flow: • Elliptic flow in Au + Au collisions at √sNN= 130 GeV, STAR Collaboration, (K.H. Ackermann et al.). Phys.Rev.Lett.86:402-407,2001 • 318 citations • Discovery of “jet quenching” • Suppression of hadrons with large transverse momentum in central Au+Au collisions at √sNN = 130 GeV, PHENIX Collaboration (K. Adcox et al.), Phys.Rev.Lett.88:022301,2002 • 384 citations W.A. Zajc

  34. 3. Initial State Hydrodynamic flow from initial spatial asymmetries Initial State How are the initial state densities and asymmetries imprinted on the detected distributions? W.A. Zajc

  35. z y x Motion Is Hydrodynamic • When does thermalization occur? • Strong evidence that final state bulk behavior reflects the initial state geometry • Because the initial azimuthal asymmetrypersists in the final statedn/df ~ 1 + 2v2(pT) cos (2 f) + ... 2v2 W.A. Zajc

  36. ~ The “Flow” Is Perfect • The “fine structure” v2(pT) for different mass particles shows good agreement with ideal (“perfect fluid”) hydrodynamics • Roughly: ∂nTmn =0  Work-energy theorem  P d(vol) = DEK mT – m0  DKET W.A. Zajc

  37. The “Flow” Knows Quarks • The “fine structure” v2(pT) for different mass particles shows good agreement with ideal (“perfect fluid”) hydrodynamics • Scaling flow parameters by quark content nq resolves meson-baryon separation of final state hadrons baryons mesons W.A. Zajc

  38. 2. Probes of dense matter Probes of Dense Matter Q. How dense is the matter?A. Do pQCD Rutherford scattering on deep interior using“auto-generated” probes: W.A. Zajc

  39. Baseline p+p Measurements with pQCD • Consider measurement of p0’s in p+p collisions at RHIC. • Compare to pQCD calculation • Phys. Rev. Lett. 91, 241803 (2003) • parton distribution functions, for partons a and b • measured in DIS, universality • perturbative cross-section (NLO) • requires hard scale • factorization between pdf and cross section • fragmentation function • measured in e+e- W.A. Zajc

  40. Au+Au: Systematic Suppression Pattern •  constancy for pT > 4 GeV/c for all centralities? Enhanced Suppressed W.A. Zajc

  41. DF The Matter is Opaque • STAR azimuthal correlation function shows ~ complete absence of “away-side” jet GONE DF = p • Partner in hard scatter is completely absorbedin the dense medium DF=0 DF = 0 W.A. Zajc

  42. Schematically (Partons) Scattered partons on the “near side” lose energy, but emerge; those on the “far side” are totally absorbed W.A. Zajc

  43. Control: Photons shine, Pions don’t • Direct photons are not inhibited by hot/dense medium • Rather: shine through consistent with pQCD W.A. Zajc

  44. Schematically (Photons) Scattered partons on the “near side” lose energy, but emerge; the direct photon always emerges W.A. Zajc

  45. central Ncoll = 975  94 Precision Probes • This one figure encodes rigorous control of systematics • in four different measurements over many orders of magnitude = = W.A. Zajc

  46. Connecting Soft and Hard Regimes Scattered partons on the “near side” lose energy, but emerge; those on the “far side” are totally absorbed • Really ? W.A. Zajc

  47. Fluid Effects on Jets ? • Mach cone? • Jets travel faster than the speed of sound in the medium. • While depositing energy via gluon radiation. • QCD “sonic boom” (?) • To be expected in a dense fluid which is strongly-coupled W.A. Zajc

  48. High pT Parton  Low pT “Mach Cone”? • The “disappearance” is that of the high pT partner • But at low pT, see re-appearance • and • “Side-lobes”(Mach cones?) W.A. Zajc

  49. Suggestion of Mach Cone? • Modifications to di-jet hadron pair correlations in Au+Au collisions at √sNN = 200 GeV, PHENIX Collaboration (S.S. Adler et al.), Phys.Rev.Lett.97:052301,2006 A “perfect” fluid response! DF W.A. Zajc

  50. How Perfect is “Perfect” ? • All “realistic” hydrodynamic calculations for RHIC fluids to date have assumed zero viscosity • h = 0 “perfect fluid” • But there is a (conjectured) quantum limit:“A Viscosity Bound Conjecture”, P. Kovtun, D.T. Son, A.O. Starinets, hep-th/0405231 • Where do “ordinary” fluids sit wrt this limit? • RHIC “fluid” mightbe at ~1 on this scale (!) (4p) T=1012 K W.A. Zajc

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