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John Harris (Yale) Lake Louise Winter Institute, 18 – 23 February 2006
Evidence for a Quark-Gluon Plasma at RHICPart 2
John Harris (Yale) Lake Louise Winter Institute, 18 – 23 February 2006
Creating and Probing the Quark-Gluon Quagmire at RHIC
John HarrisYale University
NATO ASI, Kemer, Turkey 2003
John Harris (Yale) Lake Louise Winter Institute, 18 – 23 February 2006
PHOBOS
Au + Au
On the “First Day” (at RHIC)
Large energy densities dn/ddET/d
GeV/fm3 critical
x nuclear density
Large collective flow
ed. - “completely unexpected!”
Large early pressure gradients, energy & gluon densities
Hydrodynamic & requires quark-gluon equation of state!
Quark flow & coalescence constituent quark degrees of freedom!
PHENIX
Initial Observations:Large produced particle multiplicities
ed. - “less than expected! gluon-saturation?”
dnch/d |=0 = 670, Ntotal ~ 7500
15,000 q +q in final state, > 92% are produced quarks
CGC?
John Harris (Yale) Lake Louise Winter Institute, 18 – 23 February 2006
STAR, PRL90 032301 (2003)
b ≈ 4 fmb ≈ 6.5 fmb ≈ 10 fm
peripheral collisions
Top view
Beams-eye view
On the First Day at RHIC - Azimuthal Distributions1
John Harris (Yale) Lake Louise Winter Institute, 18 – 23 February 2006
Early Pressure in System Elliptic Flow!
x
z
y
Sufficient interactions early (< 1 fm/c) in system to respond to early pressure! before self-quench (insufficient interactions)!
System is able to convert original spatial ellipticity momentum anisotropy!
Sensitive to early dynamics of system
p
p
Azimuthal anisotropy(momentum space)
1
John Harris (Yale) Lake Louise Winter Institute, 18 – 23 February 2006
Elliptic Flow Saturates Hydrodynamic Limit
• Azimuthal asymmetry of charged particles: dn/d ~ 1 + 2 v2(pT) cos (2) + ...
x
z
y
curves = hydrodynamic flowzero viscosity, Tc = 165 MeV
1
Mass dependence of v2
Requires -
• Early thermalization (0.6 fm/c)
• Ideal hydrodynamics
(zero viscosity)
“nearly perfect fluid”
• ~ 25 GeV/fm3 ( >> critical )
• Quark-Gluon Equ. of State
John Harris (Yale) Lake Louise Winter Institute, 18 – 23 February 2006
If baryons and mesons form
from independently flowing quarks
then
quarks are deconfined
for a brief moment (~ 10 -23 s), then hadronization!
Transport in gases of strongly-coupled atoms
RHIC fluid behaves like this –
a strongly coupled fluid.
Universality of Classical Strongly-Coupled Systems
Universality of classical strongly-coupled systems? Atoms, sQGP, AdS/CFT……
John Harris (Yale) Lake Louise Winter Institute, 18 – 23 February 2006
Ultra-low (Shear)Viscosity Fluids
4 s
Quantum lower viscosity bound: s > 1/4 (Kovtun, Son, Starinets)
From strongly coupled N = 4 SUSY YM theory.
2-d Rel Hydro describes STAR v2 data with /s 0.1 near lower bound!
s (limit) = 1/4
s (water) >10QGP
John Harris (Yale) Lake Louise Winter Institute, 18 – 23 February 2006
Ultra-low Viscosity Fluids
Scientific American, November 2005
“A test comes from RHIC ….. A preliminary analysis of these experiments indicates
the collisions are creating a fluid with very low viscosity.”
“Black holes have an extremely small shear viscosity – smaller than any known fluid…
Strongly interacting quarks and gluons at high T should also have a very low viscosity.”
John Harris (Yale) Lake Louise Winter Institute, 18 – 23 February 2006
“The RHIC fluid may be the
least viscous non-superfluid ever seen”
The American Institute of Physics
announced the RHIC quark-gluon liquid
as the top physics story of 2005!see http://www.aip.org/pnu/2005/
John Harris (Yale) Lake Louise Winter Institute, 18 – 23 February 2006
It Flows - Is It Really Thermalized?
“Chemical” equilibration (particle yields & ratios):
Particles yields represent equilibrium abundances
universal hadronization temperature
Small net baryon density K+/K-,B/B ratios) B ~ 25 - 40 MeV
Chemical Freezeout Conditions T = 177 MeV, B = 29 MeV T ~ Tcritical (QCD)
John Harris (Yale) Lake Louise Winter Institute, 18 – 23 February 2006
QCD Phase Diagram
At RHIC:
T = 177 MeV
T ~ Tcritical (QCD)
John Harris (Yale) Lake Louise Winter Institute, 18 – 23 February 2006
Particles are thermally distributed and flow collectively,
at universal hadronization temperature T = 177 MeV!
John Harris (Yale) Lake Louise Winter Institute, 18 – 23 February 2006
Probing Hot QCD Matter with Hard-Scattered Probes
hadrons
leading particle
hadrons
leading particle
John Harris (Yale) Lake Louise Winter Institute, 18 – 23 February 2006
High Momentum Hadrons Suppressed - Photons Not
Photons
Hadrons factor 4 – 5 suppression
dev/
AAAA /
coll pp
NR
N N
Deviations from binary scaling of hard collisions:
John Harris (Yale) Lake Louise Winter Institute, 18 – 23 February 2006
Final State Suppression / Initial State Enhancement!• The hadron spectra at RHIC from p+p, Au+Au and
d+Au collisions establish existence of
early parton energy loss, a new final-state effect, from strongly interacting, dense QCD matter in central Au-Au collisions
Au + Au Experiment d + Au Control Experiment
Final DataFinal Data
John Harris (Yale) Lake Louise Winter Institute, 18 – 23 February 2006
Energy Loss of Hard Scattered Parton
devEnergy loss requires large
pT = 4.5 – 10 GeV/c
2ˆ 5 10 GeV /fmq (Dainese, Loizides, Paic, hep-ph/0406201)
Much larger energy loss than expected from perturbation theory
Pion gas
QGP
Cold nuclear matter
RHIC data
sQGP
R. Baier
John Harris (Yale) Lake Louise Winter Institute, 18 – 23 February 2006
Heavy Charm and Beauty Quarks
LateBreaking
News
Heavy quarks thought too massive to be attenuated by medium!
Single non-photonic electrons (from D and B mesons)→ suppressed!
Heavy quarks flow like light quarks!
Au + Au non-photonic electrons
John Harris (Yale) Lake Louise Winter Institute, 18 – 23 February 2006
Hard Scattering (Jets) as a Probe of Dense Matter II
Jet event in eecollision STAR p + p jet event
Can we see jets in high energy Au+Au?
STAR Au+Au (jet?) event
John Harris (Yale) Lake Louise Winter Institute, 18 – 23 February 2006
Hard Scattering: Two-Particle Azimuthal Correlations
Technique:
Azimuthal correlation function
Trigger particle
pT > 4 GeV/c
Associate tracks
2 < pT < pT(trigger)
STAR
C2 () 1
N trigger
1
efficiencyd()N ( ,)
di-jets from p + p at 200 GeV
John Harris (Yale) Lake Louise Winter Institute, 18 – 23 February 2006
Hard Scattering: Two-Particle Azimuthal Correlations
Technique:
Azimuthal correlation function
Trigger particle
pT > 4 GeV/c
Associate tracks
2 < pT < pT(trigger)
STAR
C2 () 1
N trigger
1
efficiencyd()N ( ,)
< 0.5 > 0.5
short range correlation: jets + elliptic flow
long range correlation: elliptic flow
130 GeV Au + Au, central trigger
John Harris (Yale) Lake Louise Winter Institute, 18 – 23 February 2006
Relative Charge Dependence
Compare ++ and - - correlations to +-
STAR Preliminary @ 200 GeV/c0-10% most central Au+Au
p+p minimum bias4<pT(trig)<6 GeV/c
2<pT(assoc.)<pT(trig)
||<0.5 - ||>0.5 (scaled)
0<||<1.4
Au+Au
p+p
System (+-)/(++ & --)
p+p 2.7+-0.6
0-10% Au+Au 2.4+-0.6
Jetset 2.6+-0.7
Strong dynamical charge correlations in jet fragmentation “charge ordering”
Ref: PLB 407 (1997) 174.
pT > 4 GeV/c particle production mechanism same in central Au+Au & pp
||<0.5 - ||>0.5 (scaled)
0<||<1.4
Au+Au
p+p
John Harris (Yale) Lake Louise Winter Institute, 18 – 23 February 2006
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
C2(Au Au) C2(p p) A*(1 2v22 cos(2))
– v2 from reaction plane analysis
– A from fit in non-jet region (0.75 < || < 2.24)
Peripheral Au + Au
Away-side jet
Central Au + Au
disappears
STAR 200 GeV/cperipheral & central Au+Au
p+p minimum bias4<pT(trig)<6 GeV/c
2<pT(assoc.)<pT(trig)
John Harris (Yale) Lake Louise Winter Institute, 18 – 23 February 2006
Hammering the Nail in the Coffin
Pedestal&flow subtracted
no jet quenching!
d + Au “di-jet” correlations similar to p + p
Au + Au away-side correlation quenched!
Quenching of Away-side “jet” is final state effect
John Harris (Yale) Lake Louise Winter Institute, 18 – 23 February 2006
Hard Scattering Conclusions
High Pt hadrons suppressed in central Au + Au enhanced in d + AuBack-to-back Jets Di-jets in p + p, d + Au
(all centralities) Away-side jets quenched
in central Au + Auemission from surfacestrongly interacting medium
x
John Harris (Yale) Lake Louise Winter Institute, 18 – 23 February 2006
Where Does the Energy Go? dev
Jet correlations in proton-proton reactions.
Strong back-to-back peaks.
Jet correlations in central Gold-Gold.
Away side jet disappears for particles pT > 2 GeV
Jet correlations in central Gold-Gold.
Away side jet reappears in particles pT > 200 MeV
Azimuthal Angular CorrelationsLost energy of away-side jet is redistributed to rather large angles!
Color wakes?
J. Ruppert & B. Müller
Mach cone from sonic boom?
H. Stoecker
J. Casalderrey-Solana & E. Shuryak
Cherenkov-like gluon radiation?
I. Dremin
A. Majumder, X.-N. Wang
John Harris (Yale) Lake Louise Winter Institute, 18 – 23 February 2006
Charmonium Suppression - DeconfinementLateNews
Color screening of cc pairresults in J/ (cc) suppression!
Color Screening
cc
J/suppressed
but less than expected?
(more to do!)
Su
ppre
ssio
n F
acto
r
John Harris (Yale) Lake Louise Winter Institute, 18 – 23 February 2006
Experimental Evidence for Initial State Gluon SaturationSuppression of forward hadrons consistent with saturation of low-x gluons.
Aud
AuAu
dAuAu
dAu
x ~ 10-3x ~ 10-2x ~ 10-1
Centrality dependence & x dependence test CGC
Sup
pres
sion
Fac
tor
x ~ 10-4
x ~ 10-3
John Harris (Yale) Lake Louise Winter Institute, 18 – 23 February 2006
Summary
Quark coalescence /flow constituent quark degrees
of freedom
Extreme initial densities –
5 GeV/fm3
~ 30 - 100 x nuclear density
> 15,000 q +q in final state
Equilibrium particle abundances – Universal hadronization T ~ Tcrit
Rapid u, d, s equilibration near Tcrit
Jet energy loss – large gluon densities strongly coupled QGP
Ideal hydrodynamic flow → “perfect fluid”
- Early thermalization & Quark-Gluon EOS
Strongly-coupled system of quarks and gluons (sQGP)
formed at RHIC
Initial state gluon saturation
(color glass condensate?) -
forward rapidities low-x
d+Au is suppressed
x ~ 10-4
x ~ 10-3
p+p
Trigger jet
Away-side jet
Au+Au
John Harris (Yale) D. Allan Bromley Symposium, 8 - 9 December 2005
Signatures & Properties of the QGP at RHIC
• Large > c (T > Tc) system – QCD vacuum “melts” – NOT hadrons
• Thermalized system of quarks and gluons – NOT just q & g scattering
Large elliptic & radial flow fluid flow (“perfect”!)
Heavy quark (charm) flow
Particle ratios fit by thermal model T = 177 MeV ~ Tc (lattice QCD)
• System governed by quark & gluon Equation of State – NOT hadronic
Flow depends upon particle (constituent quark & gluon) masses
QGP EoS,, quark coalescence
• Deconfined system of quarks and gluons – NOT hadrons
Flow already at quark level, charmonium suppression (tbd)
• Weakly-interacting QGP (predicted by Lattice QCD) – NOT!!!
Strongly interacting quarks and gluons ….degrees of freedom (tbd)
• Strongly-interacting QGP (NOT predicted by Lattice QCD)
Suppression of high pT hadrons, away-side jet quenched
Large opacity (energy loss) extreme gluon/energy densities
strongly-interacting QGP (sQGP)
John Harris (Yale) Lake Louise Winter Institute, 18 – 23 February 2006
Shuryak, QM04
(flavor)
Still to do!
RAA d 2N AA dydpT
d 2N pp dydpT NcollAA
Deconfined QGP?
cc, bb suppression &
melting sequence
Chiral symmetry restoration?
Thermalized heavy flavors?
Open charm, beauty, multiply-strange baryon production & flow
Establish properties of the sQGP medium
Constituents?
Transport properties (speed of sound, diffusion…)
Flavor dependence of suppression & propagation
Light vector mesons (mass and width modifications in medium)
Direct Photon Radiation?
New phenomena…….
LHC & 40 x luminosity of RHIC & e-ion collider!
Developments in theory (lattice, hydro, parton E-loss)
“the adventure continues!”
John Harris (Yale) D. Allan Bromley Symposium, 8 - 9 December 2005
Special Thanks for Contributions to This Presentation!!
Mike Lisa
Berndt Mueller
Jamie Nagle
Paul Sorenson