1

The sQGP at RHIC: Recent Results and New

Possibilities

Richard SetoUniversity of California, Riverside

Jyvaskyla, Finland April 28, 2006

2

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

Properties of Medium

3

Busy days at RHIC

4 experiments – BRAHMS, PHENIX, PHOBOS, STAR

p+p d+Au Au+Au Cu+Cu

200 GeV

130 GeV

62.4 GeV

22.4 GeV

Run 1 - 3 Run 4 - 5 Run 6

?

4

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

5

energy density“jet” energy loss

hardprobles

energyloss

6

What is the energy density? “Jet quenching”

direct photons scale as Ncoll π0 suppressed

hadron suppression shows quenching independent of identity of produced hadron

AuAu 200 GeV

RAA

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

ε ~10-15 GeV/fm3

ε critial ~0.6 GeV/fm3

Direct γ

π0

η

7

System dependenceAu+Au and Cu+Cu sNN = 200 GeV

8

Au+Au and Cu+Cu sNN = 200 GeV

RAA Function of Npart independent of system

9

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

10

(3) q_hat = 14 GeV2/fm

(2) q_hat = 4 GeV2/fm

(1) q_hat = 0 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 is as strong as light hadrons!!!

Problem – difficult to reconcile with gluon radiative energy loss

theorists have to go back to the drawing board

11

Hadronization(so I can introduce recombination)

reco

12

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

13

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

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

14

Explanation: Recombination

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

PT baryons pT 3 pT

mesons pT 2 pT

Problem: protons exhibit “jettiness”

+ Thermal spectrum = Large pbar/π

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

Mueller et al, Hwa et al, Ko et al

15

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

16

Elliptic Flow (v2)Viscosity

Recombination

v2

v2

17

Previous Results

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

Hence Early thermalization low viscosity

PHENIXHuovinen et al

(Teany et al, Huovinen et al)

detailed hydro calculations (QGP+mixed+RG, zero viscosity) εtherm ~ 0.6 -1.0 fm/c ε~15-25 GeV/fm3

(ref: cold matter 0.16 GeV/fm3)

18

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

19

PHENIX Preliminary

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

(mT - m0)

20

PHENIX Preliminary

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

(mT - m0)Recombinationworks!

21

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 > 1

• Baryons<1

• Consistent with gluon-quark constituent models of recombination

22PHENIX(open symbols):Phys. Rev. Lett. 91,182301 (2003)

v2 of strange hadrons from STAR

• 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 > 1

• Baryons<1

• Consistent with gluon-quark constituent models of recombination

23

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 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 > 1• Baryons<1• Consistent with gluon-

quark constituent models of recombination

24

The - a test the

mass ~ proton quarks - meson

V2 behaves as recombinationsays it should

ALL hadrons seem to obey quark number scaling!

25

Hydro works in min-bias not as function of centrality

initial cond? (Rafelski)

Hydrodynamics (in the hadronic phase) and centrality

26

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”

27

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)

28

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

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

Gavai, Majumder

29

v2 heavy quarks and viscosity

The stone in the river

or the concrete canoe

University of Wisconsin Badgers engineer third-straight concrete canoe title

30

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

31

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

32

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)

33

Comment on a quantitative measure of the 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

34

Back to the beginningHow does the sQGP get started?

a candidate - the CGC

CGC

35

prediction: suppression in dAu collisions forward central

Central Midcentral

CGC

for all particles

36

What about charm? prompt muons charm(bottom) are suppressed in

dAu CGC

Xiaorong Wang, SQM 2006

Aud

Au d

North Arm

South Arm

37

Initial Temperature

Tinitial

38

Thermal photons - The Spectrum

Compare to thermal + pQCD• data consistent with

thermal + pQCD

Compare to thermal model

• data above thermal at high pT

• D. d’Enterria, D. Perresounko• nucl-th/0503054

Compare to NLO pQCD

• excess above pQCD

• L.E.Gordon and W. Vogelsang• Phys. Rev. D48, 3136 (1993)

2+1 hydro

T0ave=360 MeV(T0

max=570 MeV)

t0=0.15 fm/c

The Future – PHENIX- HBD

39

What have we learned Jet quenching

Charm quark energy loss, pretty well established Viscosity

Charm flows – further evidence that viscosity is small (interactions are strong)

Recombination baryon to meson ratio seems to obey recombination scaling All particles seem seem to obey v2 recombination scaling. [, ;Ω]

Some evidence for fine structure Evidence for quasi-partons from Recombination/Lattice

CGC indications of charm suppression in dAu collisions at forward rapidity

RHIC is now studying a state of matter clearly above the transitionQuestion: So where is it? Deconfinement? Is there a critical point?

40

Deconfinement and Screening (a puzzle)

Debyescreening

41

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

42

J/ suppression Suppression

similar in amount to SPS

consistent with screening+ regeneration

screening

regeneration

sum

43

|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

CuCu

AuAu

44

<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

45

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

Central

peripheral

46

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

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

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

47

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”

48

The FutureRHIC II RHIC II

increase in LuminosityHigh L at lower energies- the critical point

PHENIX- upgradesPHENIX- upgradesThe Nosecone Calorimeter

49

What would we like to measure?

50

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

51

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

52

HBD

VTX

NCC

PHENIX Upgrades in Central Region

Vertex Tracking (barrel and forward endcaps)

Precision measurements of charm and bottom production

Hadron blind detector (HBD) Reject Dalitz/Conversion electrons

in electron pair measurement trigger

W measurements in pp

Nose Cone Calorimeter0 and photon measurements

R3……...R2………..R1

53

2006 2007 2008 2009 2010 2011 2012

x4 Lum

RHIC II

HBD

VTX-barrel

VTX-endcap

NCCNCCMuTrigger

DAQ

R&D Phase Construction Phase Ready for Data

PHENIX/RHIC Upgrades Schedule

54

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

55

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?

56

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

57

The Nosecone Calorimeter

or

What I am really doing in Finland

58

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

59

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

60

•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

61

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

62

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

63

Where is it?

Edouard/Andrey

NCC 0.9 < h < 3.0

HBD

NCC

VTX

NCC

64

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)

65

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

66

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

Edouard

σ = 10%

10 GeV electron

67

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!

68

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

69

Come join us!