Lessons from Little Bangs on Long Island Steven Manly Univ. of Rochester Yale Physics Club May 9, 2003 steven.manly@rochester.edu http://hertz.pas.rochester.edu/smanly/ Not a systematic review of RHIC or PHOBOS results. More a personal tour of what I find interesting. Physics Club, Yale University May 9, 2003

Physics Club, Yale University May 9, 2003

Inquiring minds want to know ... Yo! What holds it together? Physics Club, Yale University May 9, 2003

leptons quarks Gauge bosons u c t d s b e e   e   W, Z, , g, G Strong interaction Hadrons Baryons qqq qq mesons p = uud n = udd K = us or us  = ud or ud nuclei atoms Electromagnetic interaction Physics Club, Yale University May 9, 2003

What forces exist in nature? What is a force? How do they interact? How do forces change with energy or temperature? How has the universe evolved? Physics Club, Yale University May 9, 2003

Similar to QED … But ... Gauge field carries the charge Quantum Chromodynamics - QCD q q qq Similar to QED … But ... Gauge field carries the charge distance energy density, temperature relative strength asymptotic freedom q q qq qq confinement Physics Club, Yale University May 9, 2003

From D.H. Perkins, Intro. to High Energy Physics Why do we believe QCD is a good description of the strong interaction? Deep inelastic scattering: There are quarks. From D.H. Perkins, Intro. to High Energy Physics Physics Club, Yale University May 9, 2003

Why do we believe QCD is a good description of the strong interaction? No direct observation of quarks: confinement Physics Club, Yale University May 9, 2003

Need the “color” degree of freedom Why do we believe QCD is a good description of the strong interaction? Need the “color” degree of freedom P. Burrows, SLAC-PUB7434, 1997 R. Marshall, Z. Phys. C43 (1989) 595 Physics Club, Yale University May 9, 2003

Why do we believe QCD is a good description of the strong interaction? e+e-  Zo  qq e+e-  Zo  qqg Event shapes Physics Club, Yale University May 9, 2003

Why do we believe QCD is a good description of the strong interaction? Measure the coupling P. Burrows, SLAC-PUB7434, 1997 Physics Club, Yale University May 9, 2003

Strong interaction is part of our heritage Physics Club, Yale University May 9, 2003

Chiral symmetry breaking: the “other” source of mass A naïve view … Quark condensate qq qq qq qq qq qq QCD vacuum Strongly interacting particles interact with the vacuum condensate … which makes them much heavier than the constituent quark masses. q Physics Club, Yale University May 9, 2003

Physics Club, Yale University May 9, 2003

Relativistic heavy ions AGS: fixed target, 4.8 GeV/nucleon pair SPS: fixed target, 17 GeV/nucleon pair RHIC: collider, 200 GeV/nucleon pair LHC: collider, 5.4 TeV/nucleon pair Two concentric superconducting magnet rings, 3.8 km circum. A-A (up to Au), p-A, p-p collisions, eventual polarized protons Funded by U.S. Dept. of Energy $616 million Construction began Jan. 1991, first collisions June 2000 Annual operating cost $100 million Reached 10% of design luminosity in 2000 (1st physics run)!! Physics Club, Yale University May 9, 2003

The view from above Physics Club, Yale University May 9, 2003

STAR Physics Club, Yale University May 9, 2003

Au-Au collision in the STAR detector Physics Club, Yale University May 9, 2003

Isometric of PHENIX Detector Physics Club, Yale University May 9, 2003

Brahms experiment From F.Videbœk Physics Club, Yale University May 9, 2003

The PHOBOS Detector (2001) z y x q f ZDC Paddle Trigger Counter Ring Counters Time of Flight Spectrometer Vertex Octagon 1m Cerenkov 4p Multiplicity Array - Octagon, Vertex & Ring Counters Mid-rapidity Spectrometer TOF wall for high-momentum PID Triggering Scintillator Paddles Counters Zero Degree Calorimeter (ZDC) z y x q f 137000 silicon pad readout channels Physics Club, Yale University May 9, 2003

Central Part of the Detector (not to scale) 0.5m Physics Club, Yale University May 9, 2003

Au-Au event in the PHOBOS detector Physics Club, Yale University May 9, 2003

The goals Establish/characterize the expected QCD deconfinement phase transition quarks+gluons hadrons Establish/characterize changes in the QCD vacuum at high energies: chiral symmetry restoration and/or disoriented chiral condensates Understand the nuclear eqn. of state at high energy density Polarized proton physics Physics Club, Yale University May 9, 2003

Terminology: angles Beamline Physics Club, Yale University May 9, 2003

Terminology: angles Pseudorapidity =  = Lorentz invariant angle with repect to the beampipe -3 +3 -2 +2 Beamline +1 -1 Physics Club, Yale University May 9, 2003

 = azimuthal angle about the beampipe Terminology: angles  = azimuthal angle about the beampipe Beamline Physics Club, Yale University May 9, 2003

Zero-degree Calorimeter Terminology: centrality peripheral collisions central collisions Nch “Spectators” Zero-degree Calorimeter “Participants” 6% Paddle Counter “Spectators” Npart Thanks to P. Steinberg for constructing much of this slide Physics Club, Yale University May 9, 2003

Signatures/observables Strange particle enhancement and particle yields Temperature J/ and ’ production/suppression Vector meson masses and widths identical particle quantum correlations DCC - isospin fluctuations Flow of particles/energy (azimuthal asymmetries) jet quenching Measured value Energy density or number of participants Each variable has different experimental systematics and model dependences on extraction and interpretation MUST CORRELATE VARIABLES Physics Club, Yale University May 9, 2003

RHIC operation Run 1 12 June, 2000: 1st Collisions @ s = 56 AGeV July 2001: 1st Collisions @ s = 200 AGeV Dec. 23, 2002: 1st d-Au collisions @ s = 200 AGeV Run 2 Run 3 Peak Au-Au luminosity = 5x1026 cm-2s-1 Design Au-Au luminosity = 2x1026 cm-2s-1 Ave luminosity for last week of ‘02 run = 0.4x1026 cm-2s-1 Run 2: Physics Club, Yale University May 9, 2003

From Thomas Roser Physics Club, Yale University May 9, 2003

From Thomas Roser Physics Club, Yale University May 9, 2003

Results from RHIC! Energy flow, Particle multiplicity  high energy density Particle production  QCD is QCD is QCD Large flow, species yields  equilibration/thermalization Spectra, flow, jets  Jet quenching Not talking about Bose-Einstein correlations, strangeness enhancement, J/ suppression, balance function, direct photon production, mass shifts, width shifts, etc. Physics Club, Yale University May 9, 2003

Energy density of proton and lattice QCD calculations Expect deconfinement phase transition to occur at an energy density of 1-2 GeV/fm3 Experimental results at RHIC imply 5 GeV/fm3 PHENIX Collaboration, PRL 87 (2001) 052301 4.6 GeV/fm3 Assumes R=size of Au nucleus and To=1fm/c Physics Club, Yale University May 9, 2003

Basic systematics of particle production PHOBOS Data on dN/dh in Au+Au vs Centrality and s dN/dh h 19.6 GeV 130 GeV 200 GeV Preliminary PHOBOS Typical systematic band (90%C.L.) Physics Club, Yale University May 9, 2003

Systematic errors not shown Energy Dependence of Central dN/dh Scale by Npart/2 & shift to h¢=h- ybeam 19.6 GeV is preliminary 19.6 GeV is preliminary Systematic errors not shown PHOBOS Au+Au dNch/dh ¢/<Npart> dNch/dh 6% central Once you are smashed by a fast moving wall of bricks, it doesn’t make much difference if the bricks are going a little faster. That only determines how far your parts are spread along the path. The “fragmentation region” extent grows with sNN Physics Club, Yale University May 9, 2003

Universality of particle production (Mueller 1983) From P.Steinberg Physics Club, Yale University May 9, 2003

Universality of particle production pp/pp A+A e+e- From P.Steinberg Physics Club, Yale University May 9, 2003

Universality of particle production p+pp+X : Universality e+e- Au+Au pp From P.Steinberg Physics Club, Yale University May 9, 2003

Elliptic flow Collision region is an extruded football/rugby ball shape Central Peripheral Physics Club, Yale University May 9, 2003

Elliptic flow b (reaction plane) Determine to what extent is the initial state spatial/momentum anisotropy is mapped into the final state. dN/d(f -YR ) = N0 (1 + 2V1cos (f-YR) + 2V2cos (2(f-YR) + ... ) Sensitive to the initial equation of state and the degree of equilibration. Affects other variables, such as HBT and spectra. Physics Club, Yale University May 9, 2003

b (reaction plane) Physics Club, Yale University May 9, 2003

Elliptic Flow at 130 GeV Phys. Rev. Lett. 89 222301 (2002) (PHOBOS : Normalized Paddle Signal) Hydrodynamic limit STAR: PRL86 (2001) 402 PHOBOS preliminary Thanks to M. Kaneta Phys. Rev. Lett. 89 222301 (2002) Physics Club, Yale University May 9, 2003

(consider velocity and early, self-quenching asymmetry) Flow vs Pt and  Hydro describes low pt vs. particle mass, fails at high pt and high- (consider velocity and early, self-quenching asymmetry) T. Hirano Physics Club, Yale University May 9, 2003

Chemical equilibration and freezeout temperature M. Kaneta, STAR Collaboration LEP F. Becattini, hep-ph/9701275 Thermal models can describe data VERY well. Thermal model lets us put data on QCD phase diagram RHIC energies appear close to Tc Physics Club, Yale University May 9, 2003

Spectra The fun starts when one compares this to pp spectra 0.2<yp <1.4 STAR results, shown at QM02 Physics Club, Yale University May 9, 2003

Comparing Au+Au and pp Spectra _ Comparing Au+Au and pp Spectra Production of high pT particles dominated by hard scattering High pT yield prop. to Ncoll (binary collision scaling) Compare to pp spectra scaled up by Ncoll Violation of Ncoll scaling Jet quenching? Au+Au _ Physics Club, Yale University May 9, 2003

Suppression in Hadron Spectra Show 130 GeV suppression in RAA plot. Shown by T. Peltzmann at QM02 Physics Club, Yale University May 9, 2003

Jet-quenching: hard parton interacts with medium, which softens the momentum spectrum in A-A relative to pp Physics Club, Yale University May 9, 2003

Peripheral Au+Au data vs. pp+flow Count tracks around very high pT particle STAR, David Hartke - shown at QM02 Physics Club, Yale University May 9, 2003

Central Au+Au data vs. pp+flow Away side jet disappears!! STAR, David Hartke - shown at QM02 Physics Club, Yale University May 9, 2003

Jet-quenching also gives break in flow vs. pT Physics Club, Yale University May 9, 2003

Initial state vs. final state effects Jet-quenching is a final state effect - “Weisaker-Williams” color field of parton interacting with colored medium. Energy loss is medium-size dependent (radiated wavelengths less than source size) Initial state effect - saturation models color glass condensate (recent review: Iancu, Leonidov, McLerran, hep-ph/0202270) can also qualitatively explain some features of the data Current d-Au run will help untangle this mess! Physics Club, Yale University May 9, 2003

RHIC/experiments running very well Showed you too much - I apologize Showed you too little - I apologize What are the lessons? RHIC/experiments running very well Up till now … characterization and refinement of models Physics Club, Yale University May 9, 2003

Hot, dense, opaque medium is formed Energy density above lattice predictions for deconfined state Local thermal equilibrium achieved Full 3-d structure away from mid-rapidity not yet understood Interesting signals being pursued … jet-quenching? Is it a duck? Perhaps standing on the precipice of a claim/discovery Remains to be seen if systematic study and pursuit of the surprises leads to anything beyond the duck! Future = statistics (J/+ more), vary species/energies, LHC Physics Club, Yale University May 9, 2003

Physics Club, Yale University May 9, 2003

Physics Club, Yale University May 9, 2003

Physics Club, Yale University May 9, 2003