john harris (yale) 16 th conference of czech & slovak physicists, hradec králové, 10 sept....

John Harris (Yale) 16th Conference of Czech & Slovak Physicists, Hradec Králové, 10 Sept. 2008

Exploring the Quark-Gluon Plasma at RHIC & LHC –Today’s Perspective

On the “First Day”

There was light!gravity electro-electro-

magnetismmagnetism

weakstrong

at 10-43 seconds

then at 10 -seconds

& 2 x 1012 Kelvin

Quark-to-hadron

phase transition

Rapid inflation

gravity, strong & E-W

forces separate

Quark-Gluon Plasma

John Harris (Yale) 16th Conference of Czech & Slovak Physicists, Hradec Králové, 10 Sept. 2008

Behavior of QCD at High Temperature

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

24

30T

John Harris (Yale) 16th Conference of Czech & Slovak Physicists, Hradec Králové, 10 Sept. 2008

Modifications to QCD Coupling Constant s

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

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

Coupling strength variesinvestigates (de-)confinement, hadronization, & intermediate objects.

low Q2high Q2

D. Gross

H.D. Politzer

F. Wilczek

QCD Asymptotic Freedom (1973)

Nobel Prize 2005

“Before [QCD] we could not go back further than 200,000 years after the Big Bang. Today…since QCD simplifies at high energy, we can extrapolate to very early times when nucleons melted…to form a quark-gluon plasma.” David Gross, Nobel Lecture (RMP 05)

John Harris (Yale) 16th Conference of Czech & Slovak Physicists, Hradec Králové, 10 Sept. 2008

Phase Diagram of QCD MatterT

emp

erat

ure

baryon density

Early universe

nucleinucleon gas

hadron gascolor

superconductor

quark-gluon plasma

Tc

~ 1

70

Me

V

0

Critical point ?

vacuum

CFLNeutron stars

see: Alford, Rajagopal, Reddy, Wilczek Phys. Rev. D64 (2001) 074017L

HC

RHIC

John Harris (Yale) 16th Conference of Czech & Slovak Physicists, Hradec Králové, 10 Sept. 2008

John Harris (Yale) U. Texas – Austin, Colloquium, 14 Nov. 2007

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)

John Harris (Yale) 16th Conference of Czech & Slovak Physicists, Hradec Králové, 10 Sept. 2008

Ultra-Relativistic Heavy Ion Collisions

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 nucleusdiameter = 14 fm

= 100 (Lorenz contracted)

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

Interaction of Au nuclei complete in few tenths fm/c

John Harris (Yale) 16th Conference of Czech & Slovak Physicists, Hradec Králové, 10 Sept. 2008

John Harris (Yale) Hadron 07 - Frascati, Italy, 8 -13 Oct. 2007

Ultra-Relativistic Heavy Ion Collision at RHIC

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!”

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 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) 16th Conference of Czech & Slovak Physicists, Hradec Králové, 10 Sept. 2008

How do RHIC Collisions Evolve?

b

1) Superposition of independent p+p:

momenta randomrelative to reaction plane

Reaction plane

John Harris (Yale) 16th Conference of Czech & Slovak Physicists, Hradec Králové, 10 Sept. 2008

How do RHIC Collisions Evolve?

b

1) Superposition of independent p+p:

2) Evolution as a bulk system

momenta randomrelative to reaction plane

High densitypressureat center

“zero” pressurein surrounding vacuum

Pressure gradients (larger in-plane) push bulk “out” “flow”

more, faster particles seen in-plane

John Harris (Yale) 16th Conference of Czech & Slovak Physicists, Hradec Králové, 10 Sept. 2008

1) Superposition of independent p+p:

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 randomrelative to reaction plane

Azimuthal Angular Distributions

John Harris (Yale) 16th Conference of Czech & Slovak Physicists, Hradec Králové, 10 Sept. 2008

On the First Day at RHIC - Azimuthal DistributionsSTAR, PRL90 032301 (2003)

b ≈ 4 fm

“central” collisions

b ≈ 6.5 fm

midcentral collisions

Top view

Beams-eye view

1

John Harris (Yale) 16th Conference of Czech & Slovak Physicists, Hradec Králové, 10 Sept. 2008

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) 16th Conference of Czech & Slovak Physicists, Hradec Králové, 10 Sept. 2008

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 StateJohn Harris (Yale) 16th Conference of Czech & Slovak Physicists, Hradec Králové, 10 Sept. 2008

Identified Hadron Elliptic Flow ComplicatedComplicated v2(pT) flow pattern is observed for identified hadrons

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

Baryons

Mesons

If the flow established at quark level, it is predicted to be simple KET KET / nq , v2 v2 / nq , nq = (2, 3 quarks) for (meson, baryon)

15000 quarksflow collectively

John Harris (Yale) 16th Conference of Czech & Slovak Physicists, Hradec Králové, 10 Sept. 2008

If baryons and mesons form

from independently flowing quarks

then

quarks are deconfined

for a brief moment (~ 10 -23 s), then hadronization!

John Harris (Yale) 16th Conference of Czech & Slovak Physicists, Hradec Králové, 10 Sept. 2008

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

Use strongly coupled N = 4 SUSY YM theory.

Derive a quantum lower viscosity bound: s > 1/4

AdS5/CFT – a 5D Correspondence of 4D Systems

• Analogy between black hole physics and equilibrium thermodynamics

• Solutions possess hydrodynamic characteristicsSimilar to fluids – viscosity, diffusion constants,….

our world - 3 + 1 dim brane

horizon

Extra dim

ension

(the bulk)

MULTIPLICITY

Entropy Black Hole Surface Area

DISSIPATION

Viscosity Graviton Absorption

John Harris (Yale) 16th Conference of Czech & Slovak Physicists, Hradec Králové, 10 Sept. 2008

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

T = 2 x 1012 K

John Harris (Yale) 16th Conference of Czech & Slovak Physicists, Hradec Králové, 10 Sept. 2008

“The RHIC fluid may be the

least viscous fluid 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) 16th Conference of Czech & Slovak Physicists, Hradec Králové, 10 Sept. 2008

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) 16th Conference of Czech & Slovak Physicists, Hradec Králové, 10 Sept. 2008

Particles are thermally distributed and flow collectively,

at universal hadronization temperature T = 177 MeV!

John Harris (Yale) 16th Conference of Czech & Slovak Physicists, Hradec Králové, 10 Sept. 2008

On the “Second” Day (~ Year) at RHIC

Probing Hot QCD Matter with Hard-Scattered Probes

hadrons

leading particle

hadrons

leading particle

parton energy loss: modification of jets and leading particles & jet-correlations

John Harris (Yale) 16th Conference of Czech & Slovak Physicists, Hradec Králové, 10 Sept. 2008

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) 16th Conference of Czech & Slovak Physicists, Hradec Králové, 10 Sept. 2008

Dynamical Origin of High pT Hadron Suppression?

What happens to the radiation?

For collisional energy losswhat about recoil energy?

Egluon > Equark, m=0 > Equark, m>0

What is the dependenceon the type of parton?

E

How does parton lose energy?

q = 2 / ^One parameterization of energy loss

q ~

John Harris (Yale) 16th Conference of Czech & Slovak Physicists, Hradec Králové, 10 Sept. 2008

Parameterization of Parton Energy Loss

q ~

Eskola, Honkanen, Salgado, WiedemannNucl Phys A747 (2005) 511

q ^

q = 5 – 15 GeV2 / fm from RHIC RAA Data ^

John Harris (Yale) 16th Conference of Czech & Slovak Physicists, Hradec Králové, 10 Sept. 2008

Interpretation of the Parton Energy Loss

q ~

RHIC data

R. Baier, Nucl Phys A715, 209c

QGP

Pion gas

Cold nuclear matter

sQGP

Energy loss requires large(also : Dainese, Loizides, Paic, hep-ph/0406201)

2ˆ 5 10 GeV /fmq 5 - 15

John Harris (Yale) 16th Conference of Czech & Slovak Physicists, Hradec Králové, 10 Sept. 2008

Heavy Quark Suppression• Using fixed order next-to-

leading log (FONL) cross

sections for charm and

beauty

Armesto, Cacciari, Dainese, Salgado, Wiedemann,PLB637:362, 2006

Insufficient suppression from theoretical models!

John Harris (Yale) 16th Conference of Czech & Slovak Physicists, Hradec Králové, 10 Sept. 2008

AdS5/CFT Again! - Initial Results on Jet Quenching

H. Liu, K. Rajagopal and U. A. Wiedemann, arXiv:hep-ph/0605178, recent PRL

from J. J. Friess, S. S. Gubser and

G. Michalogiorgakis,arXiv:hep-th/0605292.

John Harris (Yale) 16th Conference of Czech & Slovak Physicists, Hradec Králové, 10 Sept. 2008

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) 16th Conference of Czech & Slovak Physicists, Hradec Králové, 10 Sept. 2008

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

Medium-induced gluon radiation?

Polosa, C. Salgado

John Harris (Yale) 16th Conference of Czech & Slovak Physicists, Hradec Králové, 10 Sept. 2008

The suppression of high pT hadrons and the quenching of jets

indicates the presence of a high density, strongly-coupled

colored medium. !

John Harris (Yale) 16th Conference of Czech & Slovak Physicists, Hradec Králové, 10 Sept. 2008

The Quark-Gluon Plasma – Present View from RHIC

RHIC and new Large Hadron Collider (LHC) at CERN in Geneva:

Will cover 2 – 3 decades of energy (sNN ~ 20 GeV – 5.5 TeV)

To uncover the properties of hot QCD at T ~ 150 – 600 MeV)

• Large > c (T > Tc) system – Sufficient for QGP formation – NOT hadrons

• Large volume of quarks & gluons (hydrodynamics) – NOT just q & g scattering

Large elliptic & radial flow large pressure gradients

Ultra-low shear viscosity “nearly-perfect” fluid flow

Particle ratios fit by thermal model T = 177 MeV ~ Tc (lattice QCD)

• Dynamics of quarks and gluons – NOT hadrons

Flow depends upon constituent quark masses

Flow develops at quark level QGP EoS, quark coalescence

• NOT a Weakly-interacting QGP (as we initially expected from Lattice QCD)

Strongly interacting quarks and gluons NOT s ~ 0

John Harris (Yale) 16th Conference of Czech & Slovak Physicists, Hradec Králové, 10 Sept. 2008

John Harris (Yale) Hadron 07 - Frascati, Italy, 8 -13 Oct. 2007

Officially Starts Today!

Geneva with Large Hadron Collider Superimposed

John Harris (Yale) Hadron 07 - Frascati, Italy, 8 -13 Oct. 2007

The Future of RHI‘s at the LHC:

Dedicated HI experiment - ALICE

Two pp experiments with HI program:

ATLAS and CMS

Simple Extrapolation to Heavy Ion Physics at LHC

QGP (fm/c)

(GeV/fm3)

T / Tc

tform (fm/c)

√sNN (GeV) factor 28

2-4

5

1.9

0.2

200

RHIC

≤ 2

3

1.1

1

17

LHCSPS

5500

0.1 shorter

3.0 - 4.2 hotter

15-60 denser

> 10longer-lived

John Harris (Yale) 16th Conference of Czech & Slovak Physicists, Hradec Králové, 10 Sept. 2008

Heavy Ion Physics at the LHC – ExpectationsLHC Heavy Ions –

• expectations based on pQCD predictions & RHIC results• a lesson from RHIC – guided by theory + versatility + “expect the unexpected”

Soft Physics (pT ≤ 2 GeV/c) at LHC – • smooth extrapolation from SPS RHIC LHC?• expansion dynamics different? (flow, HBT, Tchem & Tkin, strange/charm/beauty)

Elliptic FlowParticle Multiplicities

Ntot ~ 6000

Ntot ~ 2000

John Harris (Yale) 16th Conference of Czech & Slovak Physicists, Hradec Králové, 10 Sept. 2008

John Harris (Yale) 16th Conference of Czech & Slovak Physicists, Hradec Králové, 10 Sept. 2008

Significant increase in hard cross sections

(pT or mass > 2 GeV/c) at LHC – large pT /total~ 2% at SPS

50% at RHIC

98% at LHC• “real” jets, large pT processes

• abundance of heavy flavors• probe early times, calculable

bb (LHC ) ~ 100 bb (RHIC)

cc (LHC) ~ 10 cc (RHIC)

Rat

e

Hard Probes with LHC Heavy Ions

LHC Heavy Ion Programs

Heavy Ion Data-taking

Pb + Pb at sNN = 5.5 TeV

John Harris (Yale) 16th Conference of Czech & Slovak Physicists, Hradec Králové, 10 Sept. 2008

The ALICE Heavy Ion Experiment

John Harris (Yale) 16th Conference of Czech & Slovak Physicists, Hradec Králové, 10 Sept. 2008

ALICE Collaboration

~ 1000 Members ~ 30 Countries ~ 100 Institutes

John Harris (Yale) 16th Conference of Czech & Slovak Physicists, Hradec Králové, 10 Sept. 2008

• Czech Republic:

Praha, Academy of Sciences of the Czech Republic, Institute of Physics

Praha, Czech Technical University of Prague CTU

Rez, Academy of Sciences of the Czech Republic, Nuclear Physics Institute

• Slovakia:

Bratislava, Comenius University, Faculty of Mathematics, Physics and Informatics

Kosice, Institute of Experimental Physics, Slovak Academy of Sciences

The ALICE Experiment Installation

John Harris (Yale) 16th Conference of Czech & Slovak Physicists, Hradec Králové, 10 Sept. 2008

RAA d 2N AA dydpT

d 2N pp dydpT NcollAA

Is the QCD phase diagram feature-less at 1 – 4 Tc?

What happens as we go up in T (e.g. coupling)?

Are there new phenomena?

What’s the range of theoretical validities (non-pQCD, pQCD, strings)?

Measure/understand parton energy loss at the fundamental level

Establish flavor (gluon and quark mass) dependence

Use jets and/or photons to establish hard-scattered parton energy

Jet modifications - longitudinal & transverse “heating”

Medium response to jet-heating (near- and away-side)

Measure/use open charm and beauty decays (also as jet-tags)

cc and bb states (Ti, screening/suppression, enhancement?)

Direct Photon Radiation?

Developments in theory (lattice, hydro, parton E-loss, string theory…)

“the next frontier!”

The Quark-Gluon Plasma at LHC – Questions

John Harris (Yale) 16th Conference of Czech & Slovak Physicists, Hradec Králové, 10 Sept. 2008

The New Yorker, Jan. 7 2007

….and the String Theory discussion/debate continues…

John Harris (Yale) 16th Conference of Czech & Slovak Physicists, Hradec Králové, 10 Sept. 2008

Special Thanks for Contributions to This Presentation!!

Miklos Gyulassy

Peter Jacobs

Mike Lisa

Thomas Ullrich

Urs Wiedemann

John Harris (Yale) 16th Conference of Czech & Slovak Physicists, Hradec Králové, 10 Sept. 2008

The End