The Strongly Interacting Quark Gluon Plasma - the Primordial Perfect Fluid

1

The Strongly Interacting Quark Gluon Plasma - the Primordial Perfect Fluid

An overview of findings at RHICRichard Seto

University of California, Riverside

Helsinki, Finland April 27, 2006

2

3

In the Beginning…

what is “quark soup” like?

had

ron

s

quark-hadronQCDphase transition

4

Phases

T

Tc

Quark Soup

Hadrons

5

Lattice Calculations

T

Tc

• Transition – Sharp Crossover at RHIC• That’s OK – 1st order for all practical

purposes

Lattice Calculations:Tc = 170 15% MeV critical ~ 0.6 GeV/fm3

Sharp Crossover

Relativistic Heavy IonsRHIC

~degrees of freedomdifference between S-B and lattice

interactionsinteractions(in hindsight)

6

RHICRHIC

Capable of colliding ~any nuclear species on ~any other species

Energy: 500 GeV for p-p 200 GeV for Au-Au

(per N-N collision) Design Luminosity

Au-Au: 2 x 1026 cm-2 s-

1

p-p : 2 x 1032 cm-2 s-

1 (polarized)

7

RHIC’s ExperimentsRHIC’s Experiments

STASTARR

8

What we know: RHIC What we know

System appears thermally and chemically equilibrated This happens early <2 fm/c

Energy density high >10 GeV/fm3

parton energy loss is large viscosity/entropy, η/s is low ( conjecture ~1/4π?) DOF ~ “quasi-quarks” ????

General picture is stable since ~ 2004 More data since QM 2005 More theory A clearer view

what is “quark soup” like?

9

A cartoon – the life history of the sQGP

0.1 1

0.1

~Energ

y

Densi

ty

(GeV

/fm

3)

10~Time (fm)

10

100

L. McLerran

(modified by R.S.)

Elliptic flow

Cross over(wanna be1st order)4

5

CGC “glasma” T. Lappi

Strongly Interacting

Recombination

~some reinteraction

Thermalization

hard probes

Partonic

10

energy density“jet” energy loss

hardprobles

energyloss

11

Using high pUsing high pTT particles aka particles aka “Jets” “Jets”

p+p

d+Au

2

2

/11 " "

/AuAu T

AAcollisions pp T

dN dydpR for normal collisions

n dN dydp

Au+Au

12

peripheral Au+Au

What is the energy density? “Jet quenching”

direct photons scale as NcolldAu hadrons scale as Ncollperiph AuAu π0 scale as Ncoll

central π0 suppressed

hadron suppression shows quenching independent of identity of produced hadron

AuAu 200 GeV

Calculations:dNg/dy ~ 1000Wicks et al, nucl-th/0512076

ε ~10-15 GeV/fm3

ε critial ~0.6 GeV/fm3

Au+Au

d+Au

Direct γ

π0

η

RAA =1 for “normal collissions”

Central AuAu

13

Jet on the “other” side?

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 for particles pT>200 MeV

Azimuthal Angular Correlations

Leading hadrons

Medium

Thermalizedpartons

pp AuAu

14

light

(M.Djordjevic PRL 94 (2004))

How is the energy lost? The sQGP has enormous stopping power

rifle bullet stopped in a tissue Original idea – energy loss by gluon radiation In 2001, Dokshitzer and Kharzeev showed “dead

cone” effect charm quark small energy loss

15

(3) q_hat = 14 GeV2/fm



(4) dNg /dy = 1000

Theory curves (1-3) from N. Armesto, et al., PRD 71, 054027

(4) from M. Djordjevic, M. Gyullasy, S.Wicks, PRL 94, 112301

What about heavy quarks? (electrons from c and b)

Charm high pT suppression ~ light hadrons!!!

Problem – difficult to reconcile with gluon radiative energy loss

theorists have to go back to the drawing board

Large Energy loss of partons energy density far in excess of critical energy density

16

Hadronizationand Recombination

hints of the DOF

reco

17

Recombination and the baryon anomaly pbar/π varies with √sNN in Cu+Cu

PHENIX PreliminaryOriginally thought:

particle production at “moderate” pTfrom mini-jet Fragmentation pbar/π- ratio

CuCu central

At ISR pbar/π- ~ 0.2

Heavy ion Collisions pbar/π- ~0.7Increasing with energy

BUT

200 GeV

22 GeV

higher energy

18

Explanation: Recombination – a hint at the DOF

Naively: recombine quasi-partons (“quasiquarks” – Gavai)

PT

baryons pT 3 pT

mesons pT 2 pT

+ Thermal “quark” spectrum

Large pbar/π

This implies that we begin in a “quasi-partonic” thermal system

Mueller et al, Hwa et al, Ko et al

19

Elliptic Flow (v2)Early Thermalizationand Recombination

v2

v2

20

Flow: A collective effect

Elliptic flow = v2 = 2nd fourier coefficient of momentum anisotropy

really?

x

yz

dn/d ~ 1 + 2 v2(pT) cos (2 ) + ...Initial spatial anisotropy converted into momentum anisotropy. Efficiency of conversion depends on the properties of the medium.

21

early thermalization?

If system free streams spatial anisotropy is lost v2 is not developed

PHENIXHuovinen et al

(Teany et al, Huovinen et al)

detailed hydro calculations (QGP+mixed+RG, zero viscosity)

therm ~ 0.6 -1.0 fm/c ~15-25GeV/fm3 (ref: crit ~0.6 GeV/fm3)

22

Recombination and v2

1) Three regions of v2

geometry-driven momentum anisotropy

geometry-driven absorption anisotropy

STAR preliminary

from partonicAND hadronicmassmass dependent dependent

from partonicquarkquark number dependent number dependent

Maya Shimomura, SQM’06

v2

v2

23

PHENIX Preliminary

2) Data from minimum bias Au+Au collisions at √sNN= 200 GeV

(mT - m0)

24

PHENIX Preliminary

3) A recombination testrescale by quark number Au+Au collisions at √sNN= 200 GeV

(mT - m0)Recombinationworks!

25

The - a test the

mass ~ proton quarks - meson

V2 behaves as recombinationsays it should

ALL hadrons seem to obey quark number scaling!

26

Hydro works in min-bias not as function of centrality

initial cond? (Rafelski)

Hydrodynamics (in the hadronic phase) and centrality

27

Recombination and centrality?

recombination and number of quark scaling works for centrality dependence

mid-centralperipheral central

Recombination works well. WHY?What is recombining?? DOF???A quasi-quark Plasma? “constituent quarks”

28

different degrees of freedom introduce different correlations between conserved charges

• assumption: conservation of charge @ hadronization local in rapidity

• introduce baryon-number strangeness correlation:

• system of particles:

• connection to Lattice susceptibilities:

DOF and Baryon-Strangeness Correlations

2 223 3BS

BS B S BSC

SS S

23 k k kk

BSk kk

n B SC

n S

3 BSBS

SS

C

QP-QGP: CBS=1

HG: CBS~ 2/3

BS-QGP: CBS~0.61

CBS: V. Koch, A. Majumder & J. Randrup, PRL95 182301 (2005)

BS-QGP: E. Shuryak, I. Zahed, PRC70 021901 (2004); PRD70 054507 (2004)

29

CBS & CQS: Lattice & Lessons

Gavai & Gupta, PRD 73, 14006, 2006

T>TC: CBS=1

• mesonic as well as baryonic bound-states ruled out via χBS and μB-derivatives thereof

Lattice confirms quasi-quark nature of flavor carriers in the deconfined phase

Gavai, Majumder

30

v2 heavy quarks and viscosity

The stone in the river

or the concrete canoe

University of Wisconsin Badgers engineer third-straight concrete canoe title

31

Flow, viscosity, and strong coupling Conversion of spatial anisotropy to

momentum anisotropy depends on viscosity Same phenomena observed in gases of

strongly interacting atoms (Li6)

weakly coupledfinite

viscosity

strongly coupled

viscosity~0

The RHIC fluid behaves like this, viscocity~0

M. Gehm, et alScience 298 2179 (2002)

now throw a stone in there

32

Heavy quarks: Single electron v2

data prefers charm flow

for charm to flow interactions must be very strong

Viscosity small

Greco, Ko, Rapp PLB 595 (2004) 202

33

B meson contribution heavy quark electron v2

B electron v2 reduces heavy quark electron v2 @ high pT

We need to directly measure D’s and B’s

pT

based on quark coalescence model c, b reso ; c,b get v2 by elastic scat. in QGP

Hendrik, Greco, Rappnucl-th/0508055 w.o. B meson (c flow)

w. B meson (c,b flow)

34

Flow, Hydrodynamics, Viscosity, Perfect Fluds….

YUK!

and String Theory

WHAT?!

Los Angles Times – May 2005

35

The subject of the flow of fluids, and particularly of water, fascinates everybody….

Fluids: Ask Feynman ( from Feynman Lecture Vol II)

Surely you’rejoking

Mr. Feynman

The subject of the flow of fluids, and particularly of water, fascinates everybody….we watch streams, waterfalls, and whirlpools, and we are fascinated by this substance which seems almost alive relative to solids. ….

36

[ ]

Viscosity and the equation of fluid flow

=density of fluid

=potential (e.g. gravitational-think mgh)

v=velocity of fluid element

p=pressure Bernoulli Sheer Viscocity

37

Non-ZERO Viscosity

smoke ring dissipates

[ ]

smoke ring diffuses

38

[ ]

ZERO Viscosity

smoke ring keeps its shape

note: you actually need viscosity to get the smoke ring started

does not diffuse

Viscosity dissipates momentum

39

the low-brow sheer force(stress) is:

Can we anyone calculate the viscosity?A primer on viscosity (Feynman again)

energy momentum stress tensor

40

Using Maldecena 10-D string theory Using Maldecena 10-D string theory magicmagic

i.e. AdS/CFT dualityi.e. AdS/CFT duality

σ(0)=area of horizon

“The key observation… is that the right hand side of the Kubo formula is known to be proportional to the classical absorption cross section of gravitons by black three-branes.”

8 G

dualGravity“QCD”strong strong couplingcoupling

Policastro, Son, Starinets hep-th 0104066

N=4 supersymmetry ~ almost QCD “SYM” (OK the coupling constant doesn’t run, but I am interested in the strong coupling case, there are a bunch of extra particles so we will divide by the entropy to get rid of the extra DOF…)

“QCD”Gravity

41

finishing it up to get finishing it up to get ηη/s/s

Entropy black hole “branes” Entropy

“QCD”

Entropyblack hole Bekenstetein, Hawking

= Area of black hole horizon

" "

black hole area

4GQCDs

136 104 B

Kss k

Kovtun, Son, Starinets hep-th 0405231

σ(0)=area of horizon

42

viscocity~0, i.e. A Perfect viscocity~0, i.e. A Perfect Fluid?Fluid?

cos

4 BRHIC

Vis ity

Entropy Density k

lowest viscositypossible?

See “A Viscosity Bound Conjecture”, P. Kovtun, D.T. Son, A.O. Starinets, hep-th/0405231

THE SHEAR VISCOSITY OF STRONGLY COUPLED N=4 SUPERSYMMETRIC YANG-MILLS PLASMA., G. Policastro, D.T. Son , A.O. Starinets, Phys.Rev.Lett.87:081601,2001 hep-th/0104066

helium water

nitrogenviscosity bound?

RHIC ~ 1?JPG, 30(2004) 1221

T=10T=101212 KK

4

s

43

When will we make a quantitative measure of When will we make a quantitative measure of the viscositythe viscosity

Upgrades -microvertex detectors - to both STAR and PHENIX will allow measurement of D and B mesons directly

Theory – will take a while

Meanwhile – viscosity better become part of our ethos

44

A strongly InteractingA strongly Interacting QGP?QGP?

RHIC data: nearing hydrodynamic prediction with zero viscosity early thermalization strong coupling

weakly coupled weakly coupled QGP? QGP?

q qscreening length

Old picture short screening length

45

A strongly Interacting QGPA strongly Interacting QGP

RHIC data: nearing hydrodynamic prediction with zero viscosity early thermalization strong coupling

sQGPsQGP

qq

screening length

New picture Long screening length Long range correlations

New Lattice DataJ//ψ stays together

at > TCF. Karsch et al, Journal of Physics G 30

(2004) 887

46

Deconfinement and Screening (a puzzle)

Debyescreening

47

A Theory update which bothers experimentalists

J/ “melts” at T>1.5 TC (Agnes Mocsy, Peter Petereczky)

“Screening likely not responsible for quarkonia suppression” (Agnes Mocsy, Peter Petereczky)

“You have to use the right potential” (CY Wong)

Does quarkonia suppression tell us anything about deconfinement!???

Who is right?!!

an experimentalist

48

J/ suppression

screening

regeneration

sum

Suppression similar in amount to SPS

consistent with screening+ regeneration

49

|y|<0.35 1.2<|y|<2.4

Aside: RAA of J/ in Au+Au/Cu+Cu

Constrained by d+Au

Most things depend on Npart independent of species Why is J/ at y=0 different for Cu and Au? Corona? Might help in understanding suppression mechanism

50

<pT2> as a function of Ncol

Au+Au = RED

Cu+Cu = BLUE

Dashed: without recombination

Solid: includes recombination

Recombination modelmatches better to the data...

nucl-th/0505055

51

Recombination predictions vs rapidity

Recombination ( Thews et al., nucl-th/0505055 ) predicts a narrower rapidity distribution with an increasing Npart.

Going from p+p to the most central Au+Au : no significant change seen in the shape of the rapidity distribution.

No recombinationAll recombination

52

RAA vs. pT in Au+Au/Cu+Cu

•Suppression of J/Y yield at low pT in both Au+Au and Cu+Cu.•High pT J/Y escape the medium? Leakage effect? [Phys. Lett. B 607 (2005)]

•Might one expect “pile up” at low pT for recombination+energy loss?

53

Questions What is the energy loss mechanism for hard quarks? Can we get a good measure of the initial temperature? Chiral Symmetry? Deconfinement? Any Clue? Is the CGC really the initial state for the sQGP Can we measure quantitatively the viscosity?

THEORY

More General Questions Do we understand why the interaction is so strong? Do we understand the DOF?

Interplay of theory and experiment – very important

both in the “CGC” and the “sQGP”

54

The FutureRHIC IIRHIC II

increase in LuminosityHigh L at lower energies- the critical point

PHENIX- upgradesPHENIX- upgradesThe Nosecone Calorimeter

55

What would we like to measure?

56

What would we like to measure? What is the energy loss mechanism for hard quarks?

Jet tomography (high pT PID, jet-jet and -jet) Can we get a good measure of the initial temperature? Chiral Symmetry?

Electromagnetic radiation (e+epair continuum, LMVM) Deconfinement? Any Clue?

Quarkonium (J/, ’ , c and (1s),(2s),(3s)) Is the CGC really the initial state for the sQGP

gluon saturation in nuclei (particle production at forward rapidity)

Can we measure quantitatively the viscosity? Heavy flavor (c- and b-production)

What is the energy loss mechanism for hard quarks? Jet tomography (high pT PID, jet-jet and -jet)

Can we get a good measure of the initial temperature? Chiral Symmetry?

Electromagnetic radiation (e+epair continuum, LMVM) Deconfinement? Any Clue?

Quarkonium (J/, ’ , c and (1s),(2s),(3s)) Is the CGC really the initial state for the sQGP

gluon saturation in nuclei (particle production at forward rapidity)

Can we measure quantitatively the viscosity? Heavy flavor (c- and b-production)

requires highestAA luminosity

57

Dalitz/conversion rejection (HBD) Precision vertex tracking (VTX)

PID (k,p,p) to 10 GeV (Aerogel/TOF)

High rate trigger (μ trigger) Precision vertex tracking (FVTX)

Electron and photon measurements Muon arm acceptance (NCC) Very forward (MPC)

PHENIX Detector Upgrades at a Glance Central arms:

Electron and Photon measurements Electromagnetic calorimeter Precision momentum determination

Hadron identification

Muon arms: Muon

Identification Momentum determination

58

2006 2007 2008 2009 2010 2011 2012

x4 Lum

RHIC II

HBD

VTX-barrel

VTX-endcap

NCCNCC

MuTrigger

DAQ

R&D Phase Construction Phase Ready for Data

PHENIX/RHIC Upgrades Schedule

59

The PHENIX central EMCAL

The central EMCAL has been one of the most important subdetectors in PHENIX

done with a calorimeter -0.35<η<0.35 and ½ of 2π

ε~ 10-15 GeV/fm3

/1

/TAA

AATbinary pp

dN dpR

N dN dp

AuAu

dAu

π 0

60

What is proposed?the NoseCone Calorimeter

NCC NCC

-3 -2 -1 0 1 2 3 η

0

cove

rage

2π

EMC

EMC

ηη coverage from 1 to 3 coverage from 1 to 3RHIC II – luminosity x10 RHIC II – luminosity x10 PHENIX acceptance x10PHENIX acceptance x10

Precision measurements possiblePrecision measurements possible

Note: DOE-1st NCC, collabor- 2nd NCC

VTX & FVTX

near full coverage for tracking and calorimetrynear full coverage for tracking and calorimetry

61

•What is the Physics I? QCD: Heavy Ion Physics and the sQGP

Heavy Ions Getting a picture of collision system

This is why the CAT scan so important. STM. Energy density (tomography) changes with rapidity large

rapidity coverage Calibrated probe: photon-jets – need large acceptance

Understanding deconfinement, Tc Recently lattice: J/ψ melts at >Tc

χcγJ/ψ – must go to forward rapidity probably the only detector capable of doing this at RHIC

jetE E γ

Leading hadronsπ0

62

What is the Physics II? QCD: Proton Nucleus Physics and the Colored Glass Condensate

More saturation at Lower x y~log(1/x) Lower x forward rapidity

xG(x)

x

measure gluon saturationvia direct photonsin forward region

The Colored Glass Condensate:The Initial Condition for HeavyIon Collisions?

Low

er

x

63

What is the Physics III?QCD: polarized pp collisions and the Spin of the Proton

Where is the spin of the proton? Idea: Measure the gluon spin contribution ΔG ΔG may be dominated by contributions from low-x

where gluons are most abundant y~log(1/x) So low x is forward rapidity

e.g. y~2 for x=10-2

Go to Forward RapidityxG(x)

x

64

Where is it?

Edouard/Andrey

NCC 0.9 < h < 3.0

HBD

NCC

VTX

NCC

65

What is it? The parts of the NCC

Silicon pads1.5x1.5 cm2

Tungsten 3 mm (EM) & 15mm (HAD)

500 um pitch Strips (“StriPixels”)

EM1electromagnetic

EM2electromagnetic

HADhadron identifier

SM“shower max”

PS“pre-shower”

18%4%

E

E E

Depth: 42X0 (1.6 λABS)

66

Silicon pads1.5x1.5 cm2

Tungsten 3 mm (EM) & 15mm (HAD)

HADhadron identifier

SM“shower max”

PS“pre-shower”

18%4%

E

E E

Depth: 42X0 (1.6λABS)

30 GeV π0

The PS and SMDetectors:

identifying π0s

500 um pitch Strips (“StriPixels”)

SM

What is it? The parts of the NCC

67

What has the NCC crew accomplished?Prototype in Test Beam at Protvino

Edouard

σ = 10%

10 GeV electron

68

How Much and When?Schedule and cost Scope of proposal to DOE:

1 NCC ~ $4M Begin Funding in FY2008 All Critical physics can be done with 1 NCC

Complete Construction in 2010 Reviewed my external committee

recommend start of funding FY 2008 in less than 18 months!

69

NCC - 2 Build second NCC from Collaboration funds

Actively seeking funds from International Collaborators

Japan, Korea, Russia, Czech Republic, …

Added Benefits: Factor ×2 in rate for rare processes Exploit muon spectrometer acceptance in pA collisions, can study both sides simultaneously

70

Come join us!

71

Connecting to lower energies unique things (so far)

ρ broadening break in Inverse

slopes @ √sNN~5

AGS/SPS/RHIC similarities strangeness

enhancement J/psi suppression

Ways to look wait for GSI wait for JPARK RHIC ~ 5GeV

Survival probability corrected for normal absorption

energy density

Karsch, Kharzeev, Satz

72

Think Carefully Varying beam energy

varies energy density – not T Looking for a sharp

“step” probably will not work at least not in T

But we also vary ρBaryon

Could we find the Critical point?

Rare probes e.g. leptons???

T/Tc

ε/T4T/Tc

1

ε

critical point?

73

RHIC II-electron cooling (Roser) x10 increase in L

over x4 from design No apparent show-stoppers

for RHIC collisions at Ecm = 5-50 GeV/n AuAu

Pre-cooling in AGS 10x luminosity ?

Electron beam cooling would make this a fantastic facility: ~100x luminosity,

Exp

ecte

d Z

DC

(w

hole

vert

ex M

B)

Rate

[H

z]

Possible increase in luminosityfor lower energiesx1000?

AGSequivalent

CERNequivalent

assume x100

PresentFullEnergy

74

spares

75

ReCo Model Modification (Hwa)

Premise:

Observables:

STAR Preliminary

STAR P

relim

inar

yThe production of Φ and

Ω particles is almost exclusively from thermal strange quarks even out

to 8 GeV/c

The ratio of Ω/Φ yields should rise linearly with pT

76

v2 of strange hadrons from STARPHENIX(open symbols):Phys. Rev. Lett. 91,182301 (2003)

• Mass ordering observed at lower pT

fit by hydro in hadronic phase

• v2 saturates for pT > 3 GeV/c

• Clear baryon/meson difference at intermediate to high pT observed

• New, high statistics measurement shows deviation from ideal scaling . Mesons above 1. baryons below 1

77PHENIX(open symbols):Phys. Rev. Lett. 91,182301 (2003)

v2 of strange hadrons from STAR

• Mass ordering observed at lower pT





78

The same scaling behaviour is observed in 62 GeV data

v2 of strange hadrons from STAR

PHENIX(open symbols):Phys. Rev. Lett. 91,182301 (2003)

Au+Au ĆsNN=62 GeV

STAR Preliminary• Mass ordering

observed at lower pT





79

Baryon/meson (pbar/-) at √s = 200 GeV AuAu

• Scales with Npart independent of system at h=0 and 3.2

Documents

The Strongly Interacting Quark Gluon Plasma - the Primordial Perfect Fluid