evidence for a quark-gluon plasma at rhic part 2

John Harris (Yale) Lake Louise Winter Institute, 18 – 23 February 2006

Evidence for a Quark-Gluon Plasma at RHICPart 2


Creating and Probing the Quark-Gluon Quagmire at RHIC

John HarrisYale University

NATO ASI, Kemer, Turkey 2003


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?


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


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


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


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……


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


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.”


“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/


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)


QCD Phase Diagram

At RHIC:

T = 177 MeV

T ~ Tcritical (QCD)


Particles are thermally distributed and flow collectively,

at universal hadronization temperature T = 177 MeV!


Probing Hot QCD Matter with Hard-Scattered Probes

hadrons

leading particle

hadrons

leading particle


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:


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


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


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


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


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


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


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


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)


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


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


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


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


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


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)


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

evidence for a quark-gluon plasma at rhic part 2

Documents

rhic quarkgluon liquidas

quarkgluon plasma

quarkgluon quagmire

quarkgluon equation

d au collisions

early thermalization

known fluid

atomsrhic fluid