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The Quenching of Jets at RHIC – Evidence for Hot Bulk QCD Matter

The Quenching of Jets at RHIC – Evidence for Hot Bulk QCD Matter. Introduction Relativistic Heavy Ion Collider (RHIC) Creating Hot Bulk QCD Matter – Overview Using Hard Scattering to Probe the Medium Suppression of High Pt Particles

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The Quenching of Jets at RHIC – Evidence for Hot Bulk QCD Matter

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  1. The Quenching of Jets at RHIC – Evidence for Hot Bulk QCD Matter • Introduction • Relativistic Heavy Ion Collider (RHIC) • Creating Hot Bulk QCD Matter – Overview • Using Hard Scattering to Probe the Medium • Suppression of High Pt Particles • Jet Quenching (Parton Energy Loss) Properties of the Medium • Conclusions & Expectations John Harris (Yale) Hadron Collider Conference, East Lansing MI, 6/14/04

  2. quark-hadron phase transition 2 x 1012 Kelvin Early Universe National Geographic (1994) & Michael Turner John Harris (Yale) Hadron Collider Conference, East Lansing MI, 6/14/04

  3. G. Schierholz et al., Confinement 2003 F. Karsch, et al. Nucl. Phys. B605 (2001) 579 Action density in 3 quark system in full QCD H. Ichie et al., hep-lat/0212036 Lattice QCD at Finite Temperature TC ~ 175  8 MeV  eC ~ 0.3 - 1 GeV/fm3 John Harris (Yale) Hadron Collider Conference, East Lansing MI, 6/14/04

  4. Phase Diagram of QCD Matter see: Alford, Rajagopal, Reddy, Wilczek Phys. Rev. D64 (2001) 074017 John Harris (Yale) Hadron Collider Conference, East Lansing MI, 6/14/04

  5. Hot Bulk QCD Matter (QGP) • Standard Model Lattice Gauge Calculations predict Deconfinement phase transition at high T in QCD • Cosmology Quark-hadron phase transition in early Universe • Astrophysics Cores of dense stars • Can we make it in the lab? • Establish bulk properties of QCD at high T and density John Harris (Yale) Hadron Collider Conference, East Lansing MI, 6/14/04

  6. BRAHMS PHOBOS RHIC PHENIX STAR Ions: A = 1 ~ 200, pp, pA, AA, AB RelativisticHeavy Ion Collider Two Concentric Superconducting Rings Design PerformanceAu + Aup + p Max snn 200 GeV 500 GeV L [cm-2 s -1 ] 2 x 10261.4 x 1031 Interaction rates 1.4 x 103 s -1 3 x 105 s -1 John Harris (Yale) Hadron Collider Conference, East Lansing MI, 6/14/04

  7. STAR RelativisticHeavy Ion Collider and Experiments John Harris (Yale) Hadron Collider Conference, East Lansing MI, 6/14/04

  8. p L p K f e jet m g Freeze-out (~ 10 fm/c) Hadronization QGP (~ few fm/c) Hard Scattering + Thermalization (< 1 fm/c) Au Au Space-time Evolution of RHIC Collisions time g e  Expansion  space John Harris (Yale) Hadron Collider Conference, East Lansing MI, 6/14/04

  9. What Can We Learn from Collisions at RHIC? • Early Stage of Collisions • Parton (fast quark and gluon) scattering and propagation • Pressure buildup from azimuthal asymmetries (elliptic flow) • Thermodynamic Properties • Bjorken longitudinal expansion and energy density • Baryo-chemical potential from baryon density/particle ratios • Pressure from flow • Entropy from particle production • Temperature from chemical freezeout (particle ratios) • Temperature from thermal freezeout (particle spectra) • Phase Transitions? • Deconfinement (s,cc, ,bb?) • Chiral Restoration • General - Collision Geometry, Space-time Evolution, Freezeout • number of participants vs centrality • stages of collisions (space-time diagram as function of geometry) • short-lived resonances • hadronization timescales • Medium Effects? • on masses and widths of resonances • on parton propagation, other? John Harris (Yale) Hadron Collider Conference, East Lansing MI, 6/14/04

  10. Creating & Probing Hot Nuclear Matter at RHIC • Create Hot Nuclear Matter • Equilibration? Thermodynamic properties? • Equation of State? • How to determine its properties? • Probe • Soft Physics reflect bulk properties • (pT < 2 GeV/c) • Hard Scattering & Heavy Quarks •  probe the medium John Harris (Yale) Hadron Collider Conference, East Lansing MI, 6/14/04

  11. Characteristics of Collisions at RHIC from Experiments global observations: Large produced particle multiplicities dnch/dh|h=0= 670, Ntotal ~ 7500 >15,000 quarks in final state, > 92% are produced quarks Large energy densities (dn/dh, dET/dh)e  5 GeV/fm3 30 - 100 x nuclear density Large elliptic flowExtreme early pressure gradients and gluon densities quark-gluon equation of state! John Harris (Yale) Hadron Collider Conference, East Lansing MI, 6/14/04

  12. Sufficient interactions early (~ 1 fm/c) in system  to respond to early pressure?  before self-quench (insufficient interactions)? System able to convert original spatial anisotropy into momentum anisotropy? Sensitive to early dynamics of initial system z p y ? x p Reaction Plane (xz) Azimuthal anisotropy (momentum space) Early Pressure in System Elliptic Flow? Initial Ellipticity (coord. space) John Harris (Yale) Hadron Collider Conference, East Lansing MI, 6/14/04

  13. z y x Large Elliptic Flow Observed • Azimuthal asymmetryof charged particles: dn/df ~ 1 + 2v2(pT) cos (2 f)+ ... John Harris (Yale) Hadron Collider Conference, East Lansing MI, 6/14/04

  14. Characteristics of Collisions at RHIC from Experiments global observations: Large produced particle multiplicities dnch/dh|h=0= 670, Ntotal ~ 7500 >92% of (>15,000) quarks of final state are produced quarks Large energy densities (dn/dh, dET/dh)e  5 GeV/fm3/ t (t ~ 0.1–1) 30 - 100 x nuclear density Large elliptic flowLarge early pressure gradients and gluon densities quark-gluon equation of state! “chemical” equilibration (particle yields & ratios): Do particles yields represent equilibrium values? John Harris (Yale) Hadron Collider Conference, East Lansing MI, 6/14/04

  15. Ratios  equilibrium values Particle Ratios  Chemical Equilibrium  Temperature • Chemically and thermally equilibrated fireball at one temperature T and one ( baryon) chemical potential m: • One ratio (e.g., p / p ) determines m / T : • Second ratio (e.g., K / p ) provides T m • Then all hadronic yields and ratios determined: John Harris (Yale) Hadron Collider Conference, East Lansing MI, 6/14/04

  16. At RHIC: T = 177 MeV T ~ Tcritical (QCD) QCD Phase Diagram John Harris (Yale) Hadron Collider Conference, East Lansing MI, 6/14/04

  17. leading particle hadrons hadrons leading particle Hard Scattering to Probe the Hot Bulk QCD Medium John Harris (Yale) Hadron Collider Conference, East Lansing MI, 6/14/04

  18. leading particle hadrons • Scattered partons propagate through matter radiate energy (~ few GeV/fm) in colored medium • suppression of high pt particles called “parton energy loss” or “jet quenching” • alter di-jets and azimuthal correlations leading particle vacuum hadrons medium Using Hard Scattered Partons to Probe the Medium • New for heavy ion physics Hard Parton Scattering • sNN = 200 GeV at RHIC (vs 17 GeV at SPS) • Jets and mini-jets  30 - 50 % of particle production high pt leading particles (jets?) azimuthal correlations John Harris (Yale) Hadron Collider Conference, East Lansing MI, 6/14/04

  19. Inclusive Hadron pt-spectra: s = 200 GeV AuAu Preliminary STAR power law: pp = d2N/dpt2 = A (p0+pt)-n John Harris (Yale) Hadron Collider Conference, East Lansing MI, 6/14/04

  20. AA cross section NN cross section Nuclear overlap integral: # binary NN collisions / inelastic NN cross section AA (pQCD) Parton energy loss R < 1 at large Pt Hadron Spectra: Comparison of AA to NN Nuclear Modification Factor RAA: AA = Nucleus-Nucleus NN = Nucleon-Nucleon John Harris (Yale) Hadron Collider Conference, East Lansing MI, 6/14/04

  21. Suppression of High Transverse Momentum Hadrons at RHIC • Large transverse momentum hadrons aresuppressed incentralcollisionsat RHIC √snn = 17.3 GeV √snn = 31 GeV √snn = 130 GeV Brookhaven Science AssociatesU.S. Department of Energy John Harris (Yale) Hadron Collider Conference, East Lansing MI, 6/14/04

  22. STAR Centrality Dependence of Suppression at RHIC Au+Au 130 GeV Phys. Rev. Lett. 89, 202301 (2002) John Harris (Yale) Hadron Collider Conference, East Lansing MI, 6/14/04

  23. Factor 4 - 5 Suppression of High Transverse Momentum Hadrons at Top RHIC Energy • Large transverse momentum hadrons aresuppressed by factor ~ 4-5 incentralcollisionsat RHIC Brookhaven Science AssociatesU.S. Department of Energy John Harris (Yale) Hadron Collider Conference, East Lansing MI, 6/14/04

  24. Final state Initial state gluon saturation? parton energy loss? nuclear effects in initial state no parton energy loss gluon saturation? p,d + A collisions - no medium Distinguish effects - initial state final state nuclear effects in initial state Is Origin of Suppression Initial or Final State? A + A collisions in medium: John Harris (Yale) Hadron Collider Conference, East Lansing MI, 6/14/04

  25. Unique to Heavy Ion Collisions! • Crucial control measurementusing d-Au collisions John Harris (Yale) Hadron Collider Conference, East Lansing MI, 6/14/04

  26. Extreme Energy Densities! • Au-Au suppression (I. Vitev and M. Gyulassy, hep-ph/0208108) • d-Au enhancement(I. Vitev, nucl-th/0302002 ) understood in an approach that combines multiple scattering with absorption ina dense partonic medium • high pT probesrequiredNg/dy ~ 1100e > 100 e0 d-Au Au-Au John Harris (Yale) Hadron Collider Conference, East Lansing MI, 6/14/04

  27. Jet event in e+e-collision STAR Au+Au (jet?) event Hard Scattering (Jets) as a Probe of Dense Matter II STAR p + p  jet event Can we see jets in high energy Au+Au? John Harris (Yale) Hadron Collider Conference, East Lansing MI, 6/14/04

  28. kT“radiative corrections” pre- and post-scattering di-jet:  Induced Gluon Radiation • ~collinear gluons in cone • “Softened” fragmentation Fragmentation: p(hadron) p (parton) Gyulassy et al., nucl-th/0302077 In QCD Medium Additional kT Significant energy loss? high pT suppression Sensitive to color properties of medium z = Studying Jets and High Pt Particles in Detail at RHIC Hard probes  early times Calculable: pQCD Abundant at RHIC, LHC John Harris (Yale) Hadron Collider Conference, East Lansing MI, 6/14/04

  29. z y x Use Geometry to Vary Parameters of Collision John Harris (Yale) Hadron Collider Conference, East Lansing MI, 6/14/04

  30. Using p+p to Study Au+Au Jet Correlations Assume: high pT triggered Au+Au event is a superposition: high pT triggered p+p event + elliptic flow of AuAu event Central Au + Au Peripheral Au + Au disappears STAR 200 GeV/c peripheral & central Au+Au p+p minimum bias 4<pT(trig)<6 GeV/c 2<pT(assoc.)<pT(trig) • v2 from reaction plane analysis • A from fit in non-jet region (0.75 < || < 2.24) Away-side jet John Harris (Yale) Hadron Collider Conference, East Lansing MI, 6/14/04

  31. Out-of-plane pTtrigger=4-6 GeV/c, 2<pTassociated<pTtrigger, ||<1 y x in-plane Back-to-back suppression out-of-plane stronger than in-plane Effect of path length on suppression is experimentally accessible Path Length Dependence of Di-jet Topologies John Harris (Yale) Hadron Collider Conference, East Lansing MI, 6/14/04

  32. no jet quenching! Pedestal&flow subtracted Df Hammering the Nail in the Coffin • STAR azimuthal correlation function shows ~ complete absence of “away-side” jet • Surface emission only? • “Partner” in hard scatter is absorbed in the dense medium John Harris (Yale) Hadron Collider Conference, East Lansing MI, 6/14/04

  33. Hard Scattering Conclusion I • The hard scattering data at RHIC from p-p, Au-Au and d-Au collisions establish existence of anew final-state effect - early (parton!) energy loss – from dense matter (new state of matter?) in central Au-Au collisions Au + Au Experiment d + Au Control Experiment Final Data Preliminary Data John Harris (Yale) Hadron Collider Conference, East Lansing MI, 6/14/04

  34. Hard Scattering Conclusion II x High Pt hadrons suppressed in central Au + Au enhanced in d + Au Back-to-back Jets Di-jets in p + p, d + Au (all centralities) Away-side jets quenched in central Au + Au emission from surface John Harris (Yale) Hadron Collider Conference, East Lansing MI, 6/14/04

  35. Major Findings of RHIC to Date Ideal hydro - Early thermalization + quark-gluon EOS Statistical model Quark coalesce./flow  constituent q d.o.f. Rapid u, d, s equilibration near Tcrit pQCD parton E loss -large early gluon density-Opaque! Gluon saturation or Color Glass Condensate? large initial gluon density Suggest QGP-based picture of RHIC collision evolution John Harris (Yale) Hadron Collider Conference, East Lansing MI, 6/14/04

  36. To do! Deconfined QGP? cc, bb suppression / melting sequence Strangeness enhancement? Thermalized? Open charm, beauty, multiply-strange baryon production & flow Establish properties of the QCD medium Probe parton E-loss with higher pT triggers, jets, g-jet Flavor dependence of suppression & propagation Light vector mesons (mass and width modifications) Direct Photon Radiation? New phenomena……. RHIC II! “the adventure continues!” John Harris (Yale) Hadron Collider Conference, East Lansing MI, 6/14/04

  37. Still the beginning John Harris (Yale) Hadron Collider Conference, East Lansing MI, 6/14/04

  38. A Comprehensive New Detector for RHIC II Physics Exploratory Working Group on a Comprehensive New Detector for RHIC-II Physics L. Bland, P. Steinberg, T. Ullrich (BNL), M. Calderon (BNL/Indiana), S. Margetis (Kent State), B. Surrow (MIT), J. Rak (New Mexico), M. Lisa, D. Magestro (Ohio State), R. Lacey (Stony Brook), G. Paic (UNAM Mexico), T. Nayak (VECC Calcutta), R. Bellwied, C. Pruneau, A. Rose, S. Voloshin (Wayne State), H. Caines, A. Chikanian, E. Finch, J.W. Harris, C. Markert, J. Sandweiss, N. Smirnov (Yale) NSAC Review, BNL, June 3, 2004

  39. The Physics Pillars of a New RHIC-II Detector • What are the detailed properties of the sQGP and can we probe a weakly interacting plasma state ? • How do particles acquire mass and is chiral symmetry restored in the dense medium ? • Is there another phase (CGC) of matter at low x, what are its features (how does it melt into the QGP) ? • What is the structure and dynamics inside the proton (parton spin, L) and is parity violation important ?

  40. Detector Concept: central |h| < 3 SC Magnet Coil, 1.5 T (“available”) pT > 0.5 GeV/c HCAL & muon detector. 15 planes, (5 cm Fe, streamer tubes, 0.3 x 4 cm resolution) (available) EMC; Crystals + Fe(Pb)/Sc (accordion type) or LAr variant, 6x6 mrad towers (available) R = 2.8 m “Very Forward Direction” (see next slide) • Tracking: • Si Vertex Detector (Si Pixel) • Primary Tracker: multi-layer • Si strip or miniTPC • mPattern Pad Detectors in • Barrel and End Caps dZ = 3.0 m PID Detectors: Cherenkov threshold (aerogel), RICH, Photon Converters, ToF (STAR clone?)

  41. Summary The New Comprehensive Detector Presents Unique New Physics Programs at RHIC II: • g - jet/leading particle physics program • flavor dependent modification of fragmentation due to medium • Quarkonium physics program • deconfinement, initial conditions, nuclear effects Unique Physics Contributions to: • Gluon saturation (CGC) • Chiral symmetry restoration • Structure and dynamics of the proton New (as yet) undetermined physics

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