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The new physics at RHIC Searching for the Quark Gluon Plasma

The new physics at RHIC Searching for the Quark Gluon Plasma. 100 AGeV + 100 AGeV Au+Au Ecm = s  40 TeV THE LITTLE BIG BANG and search for Quark Gluon Plasma. Review of soft physics sector: How much energy is available for matter production? Is the system thermalized?

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The new physics at RHIC Searching for the Quark Gluon Plasma

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  1. The new physics at RHIC Searching for the Quark Gluon Plasma • 100 AGeV + 100 AGeV Au+Au Ecm = s  40 TeV THE LITTLE BIG BANG and search for Quark Gluon Plasma. • Review of soft physics sector: • How much energy is available for matter production? • Is the system thermalized? • Is the system partonic ? • High pt suppression, the smoking gun of QGP? (more next talk) • Color Glass Condensate: the fundamental decription of nuclei? Hanoi Jens Jørgen Gaardhøje, Niels Bohr Institute

  2. The primordial soup.Can we make it in the physics kitchen ? Quark Gluon Plasma in Universe: t < 10-5 sec HG → QGP phase transition J. Harris Hadrons: now Hanoi Jens Jørgen Gaardhøje, Niels Bohr Institute

  3. q q q q q q q q q q q q q q q q q q q q q q q q q q q q q q q q q q q q q q q q q q q q q q q q q q q q q q q q ’Lattice QCD’ prediction for HG->QGP phase transition Quark-Gluon Plasma Deconfinement Asymptotic freedom F. Karsch, hep-ph/0103314 Hadron gas TC ~ 175 MeV  eC ~ 1 GeV/fm3 Hanoi Jens Jørgen Gaardhøje, Niels Bohr Institute

  4. Traditional expectations for the QGP The ’classic’ view of the Quark Gluon plasma: Deconfined system of quarks and gluons. Long lived thermalized system: plasma Asymptotic freedom: ideal gas 2 phase picture: phase transition properties (f.ex. vs. energy) chiral symmetry restored Signal expectations: Bulk: Large energy density, Entropy growth, Plateau behavior of thermodynamical variables, thermal and chemical equilibrium, large fluctuations etc… Modification of particle properties: widths and masses, color screening (J/psi), jet quenching, etc… Hanoi Jens Jørgen Gaardhøje, Niels Bohr Institute

  5. PHOBOS STAR PHENIX NIM, A499 (2003) 437 Hanoi Jens Jørgen Gaardhøje, Niels Bohr Institute

  6. dN/dy 0 y dN/dy y 0 Reaction mechanism: Stopping, transparency, & boost invariance dN/dy 0 y Hanoi Jens Jørgen Gaardhøje, Niels Bohr Institute

  7. Transparency at RHIC BRAHMS PRL in press Hanoi Jens Jørgen Gaardhøje, Niels Bohr Institute

  8. Rapidity and energy loss at RHIC Relative rapidity loss : 35% < y/yb < 44% Rapidity loss saturates! But Energy loss increases strongly dE(baryon)=75GeV ΔE(tot)=26TeV Out of available 35 TeV Hanoi Jens Jørgen Gaardhøje, Niels Bohr Institute

  9. Transparency at RHIC, but quite a lot of damage … Hanoi Jens Jørgen Gaardhøje, Niels Bohr Institute

  10. dz= 0d R2 Energy densityCharged particle multiplicity Bjorken energy density = 1/(R20) dEt/d dEt=dN • <mt> •  5 GeV/fm3 x 30 over nuclear density x 10 over nucleon density • x 3-5 over Lattice prediction Hanoi Jens Jørgen Gaardhøje, Niels Bohr Institute

  11. pp Comparison to p+p 4630 charged particles produced per collision (0-5% central) 14% increase over 130GeV 50% increase over p+p scaled by particip. => significant collective effects Hanoi Jens Jørgen Gaardhøje, Niels Bohr Institute

  12. Equilibration?Particle/antiparticle balance ’+’  ’-’ + + Hanoi Jens Jørgen Gaardhøje, Niels Bohr Institute

  13. Total relativistic energy E = mt cosh(y) mt=(pt2+m2)1/2 Produced particles in -3<y<+3 carry about 9 TeV of total energy Hanoi Jens Jørgen Gaardhøje, Niels Bohr Institute

  14. Chemical equilibrium?Hadron chemistry? • Grand Canonical Ensemble with Strangeness and charge conservation (p-)/(p+)= exp(-6u,d/T) (K-)/(K+)= exp(-2[u,d -s]/T) = exp(2s/T) [(p-)/(p+)]1/3 • Universal relationship between u,d& s • Chemical equilibration for different rapidity slices? But also at lower energies? (K-)/(K+)= [(p-)/(p+)]1/4 μ_s = 0 BRAHMS PRL 90 (2003) 112305. Hanoi Jens Jørgen Gaardhøje, Niels Bohr Institute

  15. Strange to non-strange meson ratios equilibrate K+/π+ K-/π- K/pi ratios equilibrate at midrapidity Depend strongly on baryochemical potential Hanoi Jens Jørgen Gaardhøje, Niels Bohr Institute

  16. Particle ratiosChemical equilibration? Hanoi Jens Jørgen Gaardhøje, Niels Bohr Institute

  17. q q q q q q q q q q q q q q q q q q q q q q q q q q q q q q q q q q q q q q q q q q q q q q q q q q q q q q q Phase diagram of nuclear matter Lowest baryo- chemical potential yet measured in NN collisions, Temperature around expected (Lattice QCD) q HG Hanoi Jens Jørgen Gaardhøje, Niels Bohr Institute

  18. Collective behavior:The flow of matter=>thermalization and lifetime Study azimuthal anisotropy of particle production relative to reaction plane v2: 2nd harmonic Fourier coefficient in azimuthal distribution of particles with respect to the reaction plane collision hydrodynamicexpansion late rescattering x time Hanoi Jens Jørgen Gaardhøje, Niels Bohr Institute

  19. Hydrodynamics works at RHIC • Hydrodynamics can reproduce V2 of mesons and hadrons • Comparison to models suggest: • Short lifetime (τ < 1 fm/c) • Significant reinteractions (not ideal gas) STAR PHENIX Hanoi Jens Jørgen Gaardhøje, Niels Bohr Institute

  20. Very low momenta Lack of low momenta Supports view of strongly interacting system as opposed to ideal gas PHOBOS Hanoi Jens Jørgen Gaardhøje, Niels Bohr Institute

  21. But: V2/nq is identical for mesons and baryons Suggestive of constituent quark scaling and indicates collective flow at quark level Quark recombination and flow ? • At intermediate pt: • Flow saturates • Clear difference seen between flow of baryons and mesons STAR Hanoi Jens Jørgen Gaardhøje, Niels Bohr Institute

  22. RAA 1 pt 2 0 Jet Quenching, high pt suppression.The smoking gun of QGP? Soft Hard (jets) Hanoi Jens Jørgen Gaardhøje, Niels Bohr Institute

  23. Lower energy : see High pt enhancement CERN- SPS (snn=17 GeV) High p_t enhancement seen when compared to p+p scaled by N_binary. Cronin effect: flow and quark mult scattering Hanoi Jens Jørgen Gaardhøje, Niels Bohr Institute

  24. q q q q Energy loss by stimulated gluon emission in QGP ? QCD: <E>g ln(1/L) dz  <L2> QCD-QGP Tomography Hanoi Jens Jørgen Gaardhøje, Niels Bohr Institute

  25. Jet quenching Does it persist at fwd. rapidity? QM2002 NPA715 (2003) PRL 91 (2003) 072305 Hanoi Jens Jørgen Gaardhøje, Niels Bohr Institute

  26. Au D q q  1/5 Absence of suppression at midrapidity in d+Au PRL 91 (2003) 072305 Absence of high pt suppression at midrapidity rules out initial state effects . GLV model explains Au+Au suppression and indicates ε>15GeV/fm3 And dN(gluon)/dη >1000 Hanoi Jens Jørgen Gaardhøje, Niels Bohr Institute

  27. Color Glass CondensateThe fundamental state of nuclei? X= p(parton) /p(nucleon) • Relativistically highly contracted nuclei: Gluon wave function are squeezed • Low mom. Partons are delocalized and w.f. of low pt (or low x) may overlap in nuclei = gluon condensation=> saturation • Modified parton distribution functions may lead to supression of intermediate momentum produced particles (McLerran-Venugopalan model) at forward rapidities • Saturation scale prop to exp(-y) => effect to be seen at forward rapidity Au D detector Measure large y on D side Probes small x in Au Hanoi Jens Jørgen Gaardhøje, Niels Bohr Institute

  28. BRAHMS collaboration Submitted to PRL, 2004 Color Glass Condensate in d+Au collisions? Toy model Hanoi Jens Jørgen Gaardhøje, Niels Bohr Institute

  29. Summary and conclusions • Largest energy density ever seen, more than 10 times baryon density (ε >5 GeV/fm3): incompatible with hadrons • Consistency with thermal models over |y|=2. Elliptic flow suggests very early thermalization (τ< 1 fm/c). Very interacting system (fluid). • Different saturation of flow for mesons and baryons can be explained by quark recombination models => partonic system. • Strong high-pt suppression, seen at y=0, 2, but not seen in d+Au (y=0), can be explained by parton energy loss. Models indicate (ε >15 GeV/fm3) and dN(gluon)/dη > 1000. • Color Glass Condensate observed? • Points to equilibrated partonic system not characterized by asymptotic freedom: not the classic idealized QGP, more like a partonic fluid than an ideal gas. Hanoi Jens Jørgen Gaardhøje, Niels Bohr Institute

  30. Is a unified picture emerging? Hanoi Jens Jørgen Gaardhøje, Niels Bohr Institute

  31. Hanoi Jens Jørgen Gaardhøje, Niels Bohr Institute

  32. The future:ALICE at the Large Hadron Collider (CERN) LHC: Pb+Pb 2800GeV+2800 GeV The machine to study the QGP and heavy quarks in the color medium NBI responsible for Si Forward Multiplicity Detector (50.000 channels) and TPC laser calibration System. Hanoi Jens Jørgen Gaardhøje, Niels Bohr Institute

  33. In ’BT’ at the local chinese take away………Early feb. 2004 That you can recreate the Big Bang in a particle accelerator is a simply fantastic and earth shattering…. …discovery! At the same level ..... …….as plastic slippers with acrylic lining ? Hanoi Jens Jørgen Gaardhøje, Niels Bohr Institute

  34. Hanoi Jens Jørgen Gaardhøje, Niels Bohr Institute

  35. 6% central dNch/dh ¢/<Npart>/2 Au+Au PRL 91, 052303 (2003) Hanoi Jens Jørgen Gaardhøje, Niels Bohr Institute

  36. Kinetic Freeze out Blast Wave fits at midrapidity (to pi, K and p) =>Large Radial Flow, i.e. large pressure But: correlation between T and Beta Hanoi Jens Jørgen Gaardhøje, Niels Bohr Institute

  37. Entropy production:A measure of #degrees of freedom S=<π>+κ<K>+δ<Npart> κ =1.45, δ=0.35 F= (√Snn-2mn)3/4/(√Snn)1/4 S= g1/4 . F. <Npart> Slope change → gAuAu ≈4 gpp Djamel Ouerdane, ph. d. NBI, August 2003 Hanoi Jens Jørgen Gaardhøje, Niels Bohr Institute

  38. Little difference from SPS to RHIC Consistent lifetimes: f ~ 8-10 fm/c kT (GeV/c) CERES, Nucl.Phys. A 714 (2003) 124 Two particle correlations HBT:space-time extent of source Hanoi Jens Jørgen Gaardhøje, Niels Bohr Institute

  39. Au+Au, √s = 200 GeV HBT vs reaction plane STAR Collaboration, nucl-ex/0312009 Hanoi Jens Jørgen Gaardhøje, Niels Bohr Institute

  40. Universal scaling laws for total multiplicity? Hanoi Jens Jørgen Gaardhøje, Niels Bohr Institute

  41.  1/5 Absence of suppression in d+Au at midrapidity QCD predicts large energy loss from gluon bremsstrahlung in deconfined medium: <E>g ln(1/L) dz  <L2> BRAHMS: PRL 91 (2003) 072305 Hanoi Jens Jørgen Gaardhøje, Niels Bohr Institute

  42. Hanoi Jens Jørgen Gaardhøje, Niels Bohr Institute

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