Evidence for a Quark-Gluon Plasma at RHICQuark-Gluon Plasma (Soup) John Harris (Yale) ISSP’06 Erice, Sicily, Italy, 29 Aug – 7 Sep 2006 Relativistic Heavy Ion Collider PHOBOS RHIC

John Harris (Yale) ISSP’06 Erice, Sicily, Italy, 29 Aug – 7 Sep 2006

Evidence for a Quark-Gluon Plasma at RHIC


Evidence for a Quark-Gluon Plasma at RHIC


On the “First Day”

There was light!

at 10-34 seconds

then at 10 μ-seconds

& 2 x 1012 Kelvin

Quark-to-hadron

phase transition

Rapid inflation

gravity, strong & E-W

forces separate

Quark-Gluon Plasma


Lattice QCD

few d.o.f. confined

many d.o.f. deconfined

F. Karsch, et al.

Nucl. Phys. B605

(2001) 579

TC ~ 175 ± 8 MeV C ~ 0.3 - 1 GeV/fm3

/T4 ~ # degrees of freedom


Modifications to s

heavy quark-antiquark coupling at finite T from lattice QCDO.Kaczmarek, hep-lat/0503017

Heating the vacuum modifies soft/long-wave-length processes.

Chiral symmetrybroken,confining forcesmodified.

Constituents -Hadrons,dressed quarks,quasi-hadrons,resonances?

Coupling strengthvariesinvestigatesconfinement,hadronization,& intermediateobjects.

chiral symmetry breaking limit s,c=0.43 (hep-ph/0302011)

low Q2high Q2


“In high-energy physics we have concentrated onexperiments in which we distribute a higher and higheramount of energy into a region with smaller and smallerdimensions.

In order to study the question of vacuum , wemust turn to a different direction; we should investigatesome bulk phenomena by distributing high energy overa relatively large volume.”

T.D. LeeRev. Mod. Phys. 47 (1975) 267.


Objective – Melt QCD Vacuum Deconfined QGP

Nuclear Matter(confined)

Hadronic Matter(confined)

Quark Gluon Plasma(deconfined) !

QCD vacuum color dielectric!

qq condensate

“confines” q,g to be in hadrons

• Compress or Heat to

• Melt the QCD vacuum

color conductor

deconfined color matter !

Perturbative Vacuum

ccq q

QCD vacuum

quarkquark

Thanks to Mike Lisa for animation


Phase Diagram of QCD MatterT

emp

erat

ure

baryon density

Early universe

nucleinucleon gas

hadron gascolor

superconductor

quark-gluon plasma

Tc

~ 17

0 M

eV

0

Tri-critical point ?

vacuum

CFLNeutron stars

see: Alford, Rajagopal, Reddy, Wilczek

Phys. Rev. D64 (2001) 074017

LH

C

RHIC


Quark-Gluon Plasma

• Standard Model Lattice Gauge Calculations predict

QCD Deconfinement phase transition at T = 175 MeV

• Cosmology Quark-hadron phase transition in early Universe

• Astrophysics Cores of dense stars (?)

• Establish properties of QCD at high T (and density?)

• Can we make it in the lab?

Quark-Gluon Plasma (Soup)


Relativistic Heavy Ion Collider

RHIC BRAHMSPHOBOS

PHENIXSTAR

AGS

TANDEMS

3.8 km circle

v = 0.99995

speed of light


Relativistic Heavy Ion Collider (2000 )

STAR

PHENIX

PHOBOSBRAHMS

RHIC

Design Performance Au + Au p + p

Max snn 200 GeV 500 GeV

L [cm-2 s -1 ] 2 x 1026 1.4 x 1031

Interaction rates 1.4 x 103 s -1 3 x 105 s -1

Two Concentric

Superconducting Rings

Ions: A = 1 ~ 200, pp, pA, AA,AB


Relativistic Heavy Ion Collider and Experiments

STARSTAR


Creating and Probing theQuark-Gluon Quagmire at RHIC

John Harris

Yale University

NATO ASI, Kemer, Turkey 2003


Ultra-Relativistic Heavy Ion Collisions to Melt the Vacuum

General Orientation

Hadron (baryons, mesons) masses ~ 1 GeV

Hadron sizes ~ 10-15 meters (1 fm 1 fermi)

RHIC Collisions

Ecm = 200 GeV/nn-pair

Total Ecm = 40 TeV

Gold nucleus

diameter = 14 fm

= 100

(Lorenz contracted)

= (14 fm/c) / ~ 0.1 fm/c


Ultra-Relativistic Heavy Ion Collisions to Melt the Vacuum


Space-time Evolution of RHIC Collisions

e

space

time jet

Hard Scattering + Thermalization

(< 1 fm/c)

AuAu E

xpan

sion

Hadronization

p K

Freeze-out(~ 10 fm/c)

μ

QGP (~ few fm/c)

e


η-5 0 5

η/d

chdN

0

200

400

600

800200 GeV130 GeV19.6 GeV

Au + Au

On the “First Day” (at RHIC)

Large energy densities (dn/d , dET/d )

5 GeV/fm3 5 15 critical

30 100 x nuclear density

Large collective flow

ed. - “completely unexpected!”

Due to large early pressure gradients, energy & gluon densities

Requires hydrodynamics and quark-gluon equation of state

Quark flow & coalescence constituent quark degrees of freedom!

1

PHENIX

Initial Observations:Large produced particle multiplicitiesed. - “less than expected! gluon-saturation?”

dnch/d | =0 = 670, Ntotal ~ 7500

> 15,000 q +q in final state, > 92% are produced quarks

CGC?


How do RHIC Collisions Evolve?

br

1) Superposition of independent p+p:

momenta random

relative to reaction plane


How do RHIC Collisions Evolve?

br


2) Evolution as a bulk system

momenta random


High density

pressure

at center

“zero” pressure

in surrounding vacuum

Pressure gradients (larger in-plane)

push bulk “out” “flow”

more, faster particles

seen in-plane



2) Evolution as a bulk system

Pressure gradients (larger in-plane)

push bulk “out” “flow”

more, faster particles

seen in-plane

N

- RP (rad)0 /2/4 3 /4

N

- RP (rad)0 /2/4 3 /4

momenta random


Azimuthal Angular Distributions


On the First Day at RHIC - Azimuthal Distributions

STAR, PRL90 032301 (2003)

b 4 fm

“central” collisions

b 6.5 fm

midcentral collisions

Top view

Beams-eye view

1


STAR, PRL90 032301 (2003)

b 4 fmb 6.5 fm

b 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

Initial Ellipticity(coord. space)

Reaction

Plane (xz)

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)

( ) ( )( ) )

FlowElliptic

2cos2

FlowDirected

cos2

Isotropic

1 ( 2

121

2

3

3

L444 3444 2144 344 2143421 +++= RPRP

tt

vvdydpp

d

pd

dE

x

y

p

patan=

1

fm

Hydrodynamic calculation – beam view


Elliptic Flow Saturates

Hydrodynamic Limit

• Azimuthal asymmetry of charged

particles: dn/d ~ 1 + 2 v2(pT) cos (2 ) + ...

x

z

y

curves = hydrodynamic flow

zero 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


Identified Hadron Elliptic Flow Complicated

Complicated v2(pT) flow pattern is observed for identified hadrons

d2n/dpTd ~ 1 + 2 v2(pT) cos (2 )


Hadron Elliptic Flow Reflects Quark Flow

Complicated v2(pT) flow pattern is observed for identified hadrons

d2n/dpTd ~ 1 + 2 v2(pT) cos (2 )

If the flow is established at the quark level, it is predicted to be simple

when pT pT / n , v2 v2 / n , n = (2, 3 quarks) for (meson, baryon)

15000 quarks flow collectively


Quark-number Scaling

PR

L 9

2 (2

004) 0

52302; P

RL 9

1 (2

003) 1

82301

Hadronization - a soft process

• modified by changes in runningcoupling at low Q2.

Simple hadronization model –

• quark v2 related to hadron v2 via

v2q = v2

h(pT/n)/n,

n is number of quarks in hadron

implies v2 is developed beforehadronization

model implies deconfinement


If baryons and mesons formfrom independently flowing quarks

thenquarks 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…… K.M. O’Hara et al

Science 298 (2002) 2179


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) >10

QGP


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/

Documents

Evidence for a Quark-Gluon Plasma at RHICQuark-Gluon Plasma (Soup) John Harris (Yale) ISSP’06 Erice, Sicily, Italy, 29 Aug – 7 Sep 2006 Relativistic Heavy Ion Collider PHOBOS RHIC