ObservablesObservables of theof the

deconfinementdeconfinement transition transition

EElenalena BratkovskayaBratkovskaya

Institut für Theoretische PhysikInstitut für Theoretische Physik & FIAS, Uni. Frankfurt& FIAS, Uni. Frankfurt

International Advanced School of Theoretical PhysicsInternational Advanced School of Theoretical Physics “Dense QCD phases in “Dense QCD phases in

HeavyHeavy--Ion Collisions” (DM2010). Ion Collisions” (DM2010).

August, 21 August, 21 –– September, 4, 2010September, 4, 2010,, DubnaDubna

From Big Bang to Formation of the Universe

Can we go back in time ?

time 3 min

nucleons

deuterons

αααα−−−−particles

10-3sec

quarks

gluons

photons

T~180 MeV

300000 years

atoms

15 Mrd years

our Universe

... back in time

1 event:

Au+Au

‚Re‚Re--create‘ the create‘ the Big Bang Big Bang

conditions:conditions:

matter at high temperature matter at high temperature

and pressureand pressure

such thatsuch that

nucleons/mesons decouple to nucleons/mesons decouple to

quarks and gluons quarks and gluons ----

QuarkQuark--GluonGluon--PlasmaPlasma

‚Little Bangs‘ in the ‚Little Bangs‘ in the

Laboratory : Laboratory :

HeavyHeavy--ion collisions at ion collisions at

ultrarelativistic energiesultrarelativistic energies

QGPQGP

nucleonsnucleons

HeavyHeavy--ion acceleratorsion accelerators

1 event:

Au+Au

SuperSuper--ProtonProton--Synchrotron Synchrotron –– SPS SPS --

(CERN): (CERN): Pb+Pb at 160 A GeVPb+Pb at 160 A GeV

RelativisticRelativistic--HeavyHeavy--IonIon--Collider Collider -- RHIC RHIC --

(Brookhaven): (Brookhaven): Au+Au at 21.3 A TeVAu+Au at 21.3 A TeV

STAR detector at RHICSTAR detector at RHIC

Future facilities:Future facilities: FAIR (GSI), NICA (Dubna)FAIR (GSI), NICA (Dubna)

LargeLarge Hadron ColliderHadron Collider –– LHC LHC --

(CERN): (CERN): Pb+Pb at 574 A TeVPb+Pb at 574 A TeV

3.8 km3.8 km

The QGP in Lattice QCDThe QGP in Lattice QCD

0.5 1.0 1.5 2.0 2.5 3.0

0

2

4

6

8

10

12

14

Z. Fodor et al., PLB 568 (2003) 73

Lattice QCD:

µµµµB=0

µµµµB=530 MeV

T/Tc

εε εε/T

4

TTcc = 170 MeV= 170 MeV

Lattice QCD:Lattice QCD:

energy density versus temperatureenergy density versus temperatureQQuantum uantum CCromo romo DDynamics :ynamics :

predicts strong increase ofpredicts strong increase of

the the energy density energy density εεεεεεεε at critical at critical

temperature temperature TTC C ~170 MeV~170 MeV

⇒⇒ PossiblePossible phase transition phase transition fromfrom

hadronic to hadronic to partonic matter partonic matter

(quarks, gluons) at critical energy (quarks, gluons) at critical energy

densitydensity εεεεεεεεCC ~1 GeV/fm~1 GeV/fm3 3

Critical conditions Critical conditions -- εεεεεεεεCC ~1 GeV/fm~1 GeV/fm33 , T, TC C ~170 MeV ~170 MeV -- can be reached in can be reached in

heavyheavy--ion experimentsion experiments at bombarding energiesat bombarding energies > 5 GeV/A> 5 GeV/A

‚Little Bangs‘ in the Laboratory

time

Initial State Hadronization

Au Au

Quark-Gluon-Plasma ?

quarks and gluonshadron degrees

of freedom

hadron degrees

of freedom

How can we proove that an equilibrium QGP has been How can we proove that an equilibrium QGP has been created in central Au+Au collisions ?! created in central Au+Au collisions ?!

•• QGP dileptonsQGP dileptons

•• MultiMulti--strange particle enhancement in A+A strange particle enhancement in A+A

•• Collective flow (vCollective flow (v11, v, v22))

•• Charm suppressionCharm suppression

•• Jet quenching and angular correlationsJet quenching and angular correlations

•• High pHigh pTT suppression of hadronssuppression of hadrons

•• Nonstatistical event by event fluctuations and correlations Nonstatistical event by event fluctuations and correlations

•• ... ...

Experiment: Experiment: measures measures

final hadrons and leptonsfinal hadrons and leptons

Signals of the phase transition:Signals of the phase transition:

How to learn about How to learn about

physics from data?physics from data?

Compare with theory!Compare with theory!

•• Statistical models:Statistical models:basic assumptionbasic assumption: system is described by a (grand) canonical ensemble of : system is described by a (grand) canonical ensemble of

nonnon--interacting fermions and bosons in interacting fermions and bosons in thermal and chemical equilibriumthermal and chemical equilibrium

[ [ --:: no dynamics]no dynamics]

•• Ideal hydrodynamical models:Ideal hydrodynamical models:basic assumptionbasic assumption: conservation laws + equation of state; assumption of : conservation laws + equation of state; assumption of

local thermal and chemical equilibriumlocal thermal and chemical equilibrium

[ [ --:: -- simplified dynamics]simplified dynamics]

•• Transport models:Transport models:based on transport theory of relativistic quantum manybased on transport theory of relativistic quantum many--body systems body systems --

offoff--shell Kadanoffshell Kadanoff--Baym equations for the GreenBaym equations for the Green--functions Sfunctions S<<hh(x,p) in (x,p) in

phasephase--space representation. space representation. Actual solutions:Actual solutions: Monte Carlo simulations with Monte Carlo simulations with

a large number of testa large number of test--particlesparticles

[[+: +: full dynamics | full dynamics | --:: very complicated]very complicated]

Basic models for heavyBasic models for heavy--ion collisions ion collisions

Microscopic transport models provide a unique Microscopic transport models provide a unique dynamicaldynamical description description of of nonequilibriumnonequilibrium effects in heavyeffects in heavy--ion collisions ion collisions

Our ultimate goals:Our ultimate goals:

•• Study of the Study of the phase phase

transitiontransition from from

hadronic to partonic hadronic to partonic

matter matter ––

QuarkQuark--GluonGluon--PlasmaPlasma

•• Search for the Search for the critical pointcritical point

•• Study of the Study of the inin--mediummedium properties of hadrons properties of hadrons

at high baryon density and temperatureat high baryon density and temperature

The phase diagram of QCDThe phase diagram of QCD

DileptonsDileptons

Electromagnetic probes: dileptons and photonsElectromagnetic probes: dileptons and photons

In-medium workshop, Giessen Joachim Stroth 5

Dilepton sources in HI collisionsDilepton sources in HI collisions

Dileptons are emitted from different stages of the Dileptons are emitted from different stages of the

reaction and reaction and not effected by finalnot effected by final--state interactionsstate interactions

Dilepton sources: Dilepton sources:

from the QGP via partonic (q,qbar, g) interactions:from the QGP via partonic (q,qbar, g) interactions:

from hadronic sources: from hadronic sources:

••direct decay of vector direct decay of vector

mesons (mesons (ρ,ω,φ,ρ,ω,φ,ρ,ω,φ,ρ,ω,φ,ρ,ω,φ,ρ,ω,φ,ρ,ω,φ,ρ,ω,φ,JJ/Ψ,Ψ/Ψ,Ψ/Ψ,Ψ/Ψ,Ψ/Ψ,Ψ/Ψ,Ψ/Ψ,Ψ/Ψ,Ψ‘) ‘)

••Dalitz decay of mesons Dalitz decay of mesons

and baryons (and baryons (ππππππππ00,,ηηηηηηηη, , ∆∆∆∆∆∆∆∆,…),…)

Dileptons are Dileptons are an ideal probean ideal probe to study the to study the

properties of the hot and dense mediumproperties of the hot and dense medium

γγγγγγγγ**

gg γγγγγγγγ**

γγγγγγγγ**

qq l+

l--

γγγγγγγγ**

qq

qq

qq

qq

qqqq

gggg

qq

Dilepton cocktailDilepton cocktail

••All particles decaying to All particles decaying to

dileptons are dileptons are first produced in first produced in

BB, mB or mm collisionsBB, mB or mm collisions

hea

vy

hea

vy-- i

on

co

llis

ion

sio

n c

oll

isio

ns

p+p, p+A collisionsp+p, p+A collisions

ππππππππ+p, +p, ππππππππ+A collisions+A collisions

0.00.5

1.01.5 0.0

0.5

1.0

1.5

1

3

5

7

9

M (GeV/c2)

ρρρρB=0

q (

GeV

/c)

0.00.5

1.01.5 0.0

0.5

1.0

1.5

1

2

3

4

M (GeV/c2)

ρρρρB=ρρρρ

0

q (

GeV

/c)

0.00.5

1.01.5 0.0

0.5

1.0

1.5

1

2

3

4

M (GeV/c2)

ρρρρB=2ρρρρ

0

q (

GeV

/c)

0.00.5

1.01.5 0.0

0.5

1.0

1.5

1

2

3

4

-Im Dρρρρ (M,q,ρρρρ

B,T) (GeV

-2)

T=150 MeV

M (GeV/c2)

ρρρρB=3ρρρρ

0

q (

GeV

/c)

Changes of the particle properties in the hot Changes of the particle properties in the hot

and dense baryonic mediumand dense baryonic medium

In-medium models:

chiral perturbation theory chiral perturbation theory

chiral SU(3) model chiral SU(3) model

coupledcoupled--channel Gchannel G--matrix matrix

approachapproach

chiral coupledchiral coupled--channel effective channel effective

field theory field theory

predict changes of the particle predict changes of the particle

properties in the hot and dense properties in the hot and dense

medium, e.g. medium, e.g. broadening of the broadening of the

spectral function spectral function

R. Rapp:R. Rapp: ρρρρρρρρ meson spectral functionmeson spectral function

Modelling of inModelling of in--medium spectral functions for medium spectral functions for

vector mesonsvector mesons

InIn--medium scenarios:medium scenarios:

dropping mass collisional broadening dropping mass collisional broadening dropping mass + coll. broad.dropping mass + coll. broad.

m*=mm*=m00(1(1--α ρ/ρα ρ/ρα ρ/ρα ρ/ρα ρ/ρα ρ/ρα ρ/ρα ρ/ρ00000000) ) ΓΓΓΓΓΓΓΓ(M,(M,ρρρρρρρρ)=)=ΓΓΓΓΓΓΓΓvacvac(M)+(M)+ΓΓΓΓΓΓΓΓCBCB(M,(M,ρρρρρρρρ) m* & ) m* & ΓΓΓΓΓΓΓΓCBCB(M,(M,ρ)ρ)ρ)ρ)ρ)ρ)ρ)ρ)

Collisional widthCollisional width ΓΓΓΓΓΓΓΓCBCB(M,(M,ρρρρρρρρ) = ) = γ ρ <υ σγ ρ <υ σγ ρ <υ σγ ρ <υ σγ ρ <υ σγ ρ <υ σγ ρ <υ σγ ρ <υ σVNVNtottot>>>>>>>>

0.0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 1.8 2.010

-2

10-1

100

101

102

ρρρρ/ρρρρ0000

0

1

2

3

5

M [GeV/c2]

dropping mass

A(M

)

0.0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 1.8 2.010

-3

10-2

10-1

100

101

102

ρρρρ/ρρρρ0000

0

1

2

3

5

M [GeV/c2]

collisional broadening

A(M

)

ρρρρρρρρ−−−−−−−−meson spectral function:meson spectral function:

0.0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 1.8 2.010

-3

10-2

10-1

100

101

102

M [GeV/c2]

ρρρρ/ρρρρ0000

0

1

2

3

5

dropping mass + collisional broadening

A(M

)

pole position mpole position m00 : shift: shift to low Mto low M

spectral functionspectral function : narrowing: narrowing

Consequences when Consequences when increasing the baryon density increasing the baryon density ρ:ρ:ρ:ρ:ρ:ρ:ρ:ρ:

pole position mpole position m00 : unchanged : unchanged

spectral functionspectral function : broadening: broadening

pole position mpole position m00 : shift: shift to low M to low M

spectral functionspectral function : broadening: broadening

Dilepton spectra from heavy-ion collisionsDilepton spectra from heavyDilepton spectra from heavy--ion collisionsion collisions

Dileptons (e+eDileptons (e+e-- or or µµµµµµµµ++µµµµµµµµ-- pairs)pairs) are an are an ideal probeideal probe for vector meson for vector meson

spectroscopy in the spectroscopy in the nuclear mediumnuclear medium and for the nuclear dynamics !and for the nuclear dynamics !

CERES, HELIOSCERES, HELIOS--3 data 3 data

(1995)(1995)

No medium effects:No medium effects:

too much yield in the too much yield in the ρ ρ ρ ρ ρ ρ ρ ρ peakpeak

missing yield around missing yield around

M~0.5 GeVM~0.5 GeV

InIn--medium spectral function:medium spectral function:

works rather wellworks rather well

Dilepton spectra at Dilepton spectra at SIS energies SIS energies (BEVALAC and HADES) show (BEVALAC and HADES) show similar similar

inin--medium modificationmedium modification of vector meson spectral functionsof vector meson spectral functions

Dileptons: NA60 Dileptons: NA60 ((µµµµµµµµ++µµµµµµµµ-- spectra)spectra)

High precision NA60 data allow to distinguish among inHigh precision NA60 data allow to distinguish among in--medium models!medium models!

Clear evidence for a broadening of the Clear evidence for a broadening of the ρ ρ ρ ρ ρ ρ ρ ρ spectral function!spectral function!

oppositeopposite--side dimuonsside dimuons

combinatorial backgroundcombinatorial background

resulting signalresulting signal

Excess spectrum = Excess spectrum =

resulting signal resulting signal ––

‚‚cocktailcocktail‘‘ sourcessources

Exp. data vs theory (Rapp et. al.)Exp. data vs theory (Rapp et. al.)

-- models for models for ρρρρρρρρ spectral function:spectral function:

vacuum s.f.vacuum s.f.

dropping mass (Brown/Rho)dropping mass (Brown/Rho)

coll. broad. (Rapp/Wambach)coll. broad. (Rapp/Wambach)

NA60 data vs. HSD transportNA60 data vs. HSD transport

•• NA60 data are better NA60 data are better

described bydescribed by inin--medium medium

scenario with collisional scenario with collisional

broadening broadening

0.2 0.4 0.6 0.8 1.0 1.20

100

200

300

400

500

600

700

800

0.2 0.4 0.6 0.8 1.0 1.20

500

1000

1500

2000

2500

0.2 0.4 0.6 0.8 1.0 1.20

500

1000

1500

2000

2500

3000

0.2 0.4 0.6 0.8 1.0 1.20

200

400

600

800

1000

1200

1400

1600

1800

In+In, 160 A GeV, all pTPeripheral

dN

/dM

p

er 2

0 M

eV

Semi-Peripheral

NA60

Semi-Central

M [GeV/c2]

dN

/dM

p

er 2

0 M

eV

HSD:

free s. f.

coll. broad.

dropp. mass

+ coll. broad.

Central

M [GeV/c2]

E. B., W. Cassing, O. Linnyk, PLB 670 (2009) 428E. B., W. Cassing, O. Linnyk, PLB 670 (2009) 428

•• High M tail not reproduced in HSD High M tail not reproduced in HSD NonNon--hadronichadronic origin? origin?

HSD HSD –– full full offoff--shell propagationshell propagation

of inof in--medium spectral functions medium spectral functions

through the hadronic mediumthrough the hadronic medium

-- models for models for ρρρρρρρρ spectral function:spectral function:

vacuum spectral functionvacuum spectral function

dropping mass (Brown/Rho)dropping mass (Brown/Rho)

coll. broad. (Rapp/Wambach)coll. broad. (Rapp/Wambach)

Dileptons at SPS: CERES (eDileptons at SPS: CERES (e++ee-- spectra)spectra)

0.0 0.2 0.4 0.6 0.8 1.0 1.2

10-9

10-8

10-7

10-6

10-5

10-4

0.0 0.2 0.4 0.6 0.8 1.0 1.2

10-9

10-8

10-7

10-6

10-5

10-4

HSD:

free s.f.

coll. broad.

CERES:

7% (2008 data)

30% (95/96 data)

pT> 200 MeV/c

θθθθe

+e

-> 35 mrad

2.1 < ηηηη < 2.65

<d

Ne+

e- /d

M>

/ <

Nch

> [

(100 M

eV/c

2 )-1]

M [GeV/c2]

Pb+Au, 160 A GeV, 7%

CERES

HSD:

free s.f.

coll. broad.

pT> 200 MeV/c

θθθθe

+e

-> 35 mrad

2.11 < ηηηη < 2.64

<d

Ne+

e- /d

M>

/ <

Nch

> [

(100 M

eV/c

2 )-1] Pb+Au, 40 A GeV, 30%

•• CERES data are better described byCERES data are better described by inin--medium scenario with collisional broadening medium scenario with collisional broadening

0.0 0.2 0.4 0.6 0.8 1.0 1.20.0

0.2

0.4

0.6

0.8

1.0

1.2

1.4

1.6

1.8

CERES (2008 data): 'ρρρρ'

HSD:

ρρρρ: free s.f.

ρρρρ: coll. broad.

total yield − − − − HSD 'cocktail'

x 10-6

Pb+Au, 160 A GeV, 7%

pT> 200 MeV/c

θθθθe

+e

-> 35 mrad

2.1 < ηηηη < 2.65

<d

Ne+

e-(tota

l-'c

ock

tail

') /

dM

> /

<N

ch>

[(1

00 M

eV/c

2 )-1]

M [GeV/c2]

Dileptons at RHICDileptons at RHIC

PHENIX: Au+AuPHENIX: Au+AuPHENIX: ppPHENIX: pp

•• Dilepton cocktail Dilepton cocktail provides aprovides a good description of pp data good description of pp data

as well asas well as peripheral Au+Au data, peripheral Au+Au data,

however,however, fails in describing the central bins!fails in describing the central bins!

‚‚excessexcess‘‘

Dileptons at RHIC: data vs. theor. modelsDileptons at RHIC: data vs. theor. models

PHENIX:PHENIX:

Au+AuAu+Au

•• Models provide a Models provide a good description of pp datagood description of pp data

•• Standard inStandard in--medium effects of vector mesons medium effects of vector mesons ---- compatible with the NA60 and compatible with the NA60 and

CERES data at SPS CERES data at SPS –– do not explain the large enhancement observed by do not explain the large enhancement observed by

PHENIXPHENIX in the invariant mass from 0.2 to 0.5 GeV in central Au+Au collin the invariant mass from 0.2 to 0.5 GeV in central Au+Au collisions isions

at s at s 1/21/2=200 GeV (relative to pp collisions) =200 GeV (relative to pp collisions) PHENIX dilepton puzzle ?!PHENIX dilepton puzzle ?!

QGP radiation QGP radiation -- PHSDPHSD

0.0 0.2 0.4 0.6 0.8 1.0

10-5

10-4

10-3

10-2

10-1

0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.510

-8

10-7

10-6

10-5

10-4

10-3

10-2

10-1

ππππ0 ηηηη ηηηη'

ρρρρ ωωωω φφφφ

∆∆∆∆ a1 D

Au+Au, s1/2

=200 GeV, 0-10% central

M [GeV/c2]

1/N

evt d

N/d

M [1

/(G

eV/c

2)] PHENIX

HSD

PHSD q+qbar->γγγγ*

q+qbar->γγγγ*+g

q+g->γγγγ*+q

M [GeV/c2]

•• The The contribution contribution of the QGP to the of the QGP to the dileptondilepton radiation clearly increases with radiation clearly increases with

centralitycentrality..

•• There is a large There is a large discrepancy discrepancy between the data and PHSD for M=0.15between the data and PHSD for M=0.15--0.7 0.7 GeVGeV. .

•• However,However, partonicpartonic channels dominate the observed yield at high masses !channels dominate the observed yield at high masses !

O. LinnykO. Linnyk

PHENIX dilepton puzzle ?PHENIX dilepton puzzle ?

MultiMulti--strange particle enhancement in Au+Austrange particle enhancement in Au+Au

Strange particlesStrange particlesStrange particles

Mesons:

( ) ( )( ) ( )( ) ( )( ) ( ) GeV 0.892m sdKsdK

suKsuK

GeV 0.494m sdKsdK

suKsuK

K

0*0*

**

K

00

=

=−+

−+

Baryons:Baryons:

( )( ) ( ) ( )( ) ( )( ) GeV 1.672msssΩ

GeV 1.315mdssΞussΞ

GeV 1.189mddsΣuusΣudsΣ

GeV 1.116mudsΛ

Ω

Ξ

0

Σ

0

Λ

0

=

=

=

=

−

−

−+

Strangeness |S|=1Strangeness |S|=1

Strangeness S= Strangeness S= --11

S= S= --22

S= S= --33

Strangeness production in A+A collisionsStrangeness production in A+A collisions

• Initially:

no strangeness• Finally:

= strange particles

• How can strangeness be produced?

pairsss,

•• Strangeness Strangeness production in a hadronic world (at low energy):production in a hadronic world (at low energy):N+N N+N −−−−−−−−> > > > > > > > N+N+Λ+Λ+Λ+Λ+Λ+Λ+Λ+Λ+K requires K requires ∆∆∆∆∆∆∆∆E = 2ME = 2MNN--(M(MKK+M+MΛΛΛΛΛΛΛΛ+M+MNN)) =670 MeV=670 MeV

π+π+π+π+π+π+π+π+N N −−−−−−−−> Λ+> Λ+> Λ+> Λ+> Λ+> Λ+> Λ+> Λ+K K ∆∆∆∆∆∆∆∆E = (ME = (Mππππππππ+M+MNN))--(M(MKK+M+MΛΛΛΛΛΛΛΛ)) =535 MeV=535 MeV

•• Strangeness production in a QGP:Strangeness production in a QGP:bare mass of strange quark mbare mass of strange quark mSS~ 130 MeV~ 130 MeV

=> => ss--sbar pair production sbar pair production

by by qq--qbar annihilationqbar annihilation q+qbar q+qbar −−−−−−−−>>>>>>>>s+sbars+sbar

needs only needs only ∆∆∆∆∆∆∆∆E=260 MeVE=260 MeV

=> s=> s--sbar pair can be also produced by sbar pair can be also produced by

gluon fusion g+g gluon fusion g+g −−−−−−−−>>>>>>>>s+sbars+sbar

Strong enhancement of strangeness production in a QGP !Strong enhancement of strangeness production in a QGP !RafelskiRafelski--MüllerMüller: Phys. Rev.: Phys. Rev. LettLett. 48 (1982) 1066. 48 (1982) 1066

=> => strangeness enhancement strangeness enhancement increasincreaseses with strangeness contentwith strangeness content ––

ststrongerronger effect for effect for multimulti--strangestrange hadronshadrons ΞΞΞΞΞΞΞΞ(uss), (uss), ΩΩΩΩΩΩΩΩ(sss)(sss)

How strangeness can be produced in QGP ?How strangeness can be produced in QGP ?

Strangeness enhancement at Strangeness enhancement at SPSSPS energiesenergies

Enhancement grows:Enhancement grows:

with the with the number of wounded nucleonsnumber of wounded nucleons (centrality)(centrality)

with the with the number strange valence quarksnumber strange valence quarks: multi: multi--strange particles strange particles

ΞΞΞΞΞΞΞΞ(uss) and (uss) and ΩΩΩΩΩΩΩΩ(sss)(sss) are stronger enhanced for central collisionsare stronger enhanced for central collisions

Experimental observations

Strangeness enhancement at RHIC energiesStrangeness enhancement at RHIC energies

Experiment Experiment

ΞΞΞΞΞΞΞΞ and and ΩΩΩΩΩΩΩΩ enhancement for central collisions !enhancement for central collisions !

Centrality dependence of (multiCentrality dependence of (multi--)strange (anti)strange (anti--)baryons)baryons

enhanced production of (multienhanced production of (multi--) strange antibaryons in PHSD ) strange antibaryons in PHSD

compare to HSDcompare to HSD

strange strange

antibaryonsantibaryons

_ __ _

ΛΛΛΛΛΛΛΛ++ΣΣΣΣΣΣΣΣ00

multimulti--strange strange

antibaryonantibaryon

__

ΞΞΞΞΞΞΞΞ++

0 100 200 300 4000.00

0.01

0.02

0.03

0.04

0.05

0.06

0 100 200 300 4000.000

0.002

0.004

0.006

0.008

0.010

NA57

NA49

HSD

PHSD

ΛΛΛΛ+ΣΣΣΣ0

NwoundN

wound

Pb+Pb, 158 A GeV, mid-rapidity _ _

Λ+ΣΛ+ΣΛ+ΣΛ+Σ0000

dN

/dy |

y=

0 / N

wou

nd

0 100 200 300 40010

-4

10-3

10-2

0 100 200 300 400

10-4

10-3

HSD

PHSD NA57

NA49

ΞΞΞΞ−−−−

d

N/d

y | y

=0 /

Nw

ound

________

ΞΞΞΞ++++

Pb+Pb, 158 A GeV, mid-rapidity

Nwound

Nwound

multimulti--strange strange

baryonbaryon

ΞΞΞΞΞΞΞΞ−−−−−−−−--

strange strange

baryonsbaryons

ΛΛΛΛΛΛΛΛ++ΣΣΣΣΣΣΣΣ00

Cassing & Bratkovskaya, NPA 831 (2009) 215Cassing & Bratkovskaya, NPA 831 (2009) 215

Collective flow (vCollective flow (v11, v, v22))

in Au+Auin Au+Au

x

z

Directed flow v1 & elliptic flow v2Directed flow vDirected flow v1 1 & elliptic flow v& elliptic flow v22

( )

>+

−=<

>=<

+++=

22

22

yx

yx

2

T

x1

21

TTTT

pp

ppv

p

pv

...)cos(22v)cos(2v12π

1

dpdyp

dN

ddpdyp

dNϕϕ

ϕ

v2 = 7%, v1=0

v2 = 7%, v1=-7%

v2 = -7%, v1=0

Ou

t-of-

pla

ne

In-plane

Y

X

-- directed flowdirected flow

-- elliptic flow elliptic flow

VV2 2 > 0 > 0 indicates indicates inin--planeplane emission of particlesemission of particles

VV2 2 < 0 < 0 corresponds to a corresponds to a squeezesqueeze--out out perpendicular perpendicular

to the reaction plane (to the reaction plane (outout--ofof--planeplane emission)emission)

x

zNon central Au+Au collisions :interaction between constituents leads to apressure gradient => spatial asymmetry is converted to an asymmetry in momentum space => collective flow

Y

0.1 1 10

-0.15

-0.10

-0.05

0.00

0.05

0.10

0.15

0.20

RBUU (Munich), potential

RBUU (Giessen), potential

RBUU (Giessen), cascade

GiBUU, potential

GBUU, cascade

Au+Au, mid-rapidity, semi-central

protons

EOS/ E895/ E877

FOPI/ Plastic Ball/ LAND/ MSU

v2

Ebeam

[GeV]

Collective flow: vCollective flow: v22 excitation function (SISexcitation function (SIS--AGS)AGS)

Proton vProton v22 at at low energylow energy shows sensitivity to the shows sensitivity to the nucleon potentialnucleon potential..

Cascade Cascade codes fail to describe the exp. data.codes fail to describe the exp. data.

AGSAGS energies: energies: transitiontransition from squeezefrom squeeze--out to inout to in--plane elliptic flowplane elliptic flow

Collective flow: vCollective flow: v22 excitation functionexcitation function

vv2 2 excitation functions from the stringexcitation functions from the string--hadronic transport model UrQMD: hadronic transport model UrQMD:

low energies low energies -- sensitivity to the sensitivity to the nucleon potentialnucleon potential

high energieshigh energies -- missing vmissing v2 2 -- QGP pressure?! QGP pressure?!

Elliptic flow v2 in Au+Au at RHIC Elliptic flow vElliptic flow v2 2 in Au+Au at RHIC in Au+Au at RHIC

0 50 100 150 200 250 300 350 400

0.00

0.02

0.04

0.06

0.08

0.10

PHOBOS

HSD

Au+Au, s1/2

=200 GeV

charged particles

|ηηηη|<1

v2

-6 -4 -2 0 2 4 6

0.00

0.01

0.02

0.03

0.04

0.05

0.06v

2

Apart

PHOBOS

HSD

Au+Au, s1/2

=200 GeV

charged particles

v2

ηηηη

•• STAR data on vSTAR data on v22 of charged of charged

hadrons are hadrons are NOTNOT reproduced in the reproduced in the

hadronhadron--string picture (UrQMD) =>string picture (UrQMD) =>

evidence forevidence for huge plasma pressure ?! huge plasma pressure ?!

•• PHOBOS data on vPHOBOS data on v22 for charged hadrons for charged hadrons

((all pall pTT) are underestimated in HSD by ) are underestimated in HSD by ~30%~30%

PRC 67 (2003) 054905, Nucl. Phys. A 735 (2004) 277PRC 67 (2003) 054905, Nucl. Phys. A 735 (2004) 277

factor 2factor 2

HSDHSD

UrQMDUrQMD

Elliptic Flow at 62.4 Elliptic Flow at 62.4 and 200 and 200 GeVGeV Au+AuAu+Auv

2

pT [GeV/c]

PHENIX preliminary

√sNN= 62.4 GeV Au+Au

centrality : 0-84%

stat. error only

sys. error <20%

v2

pT [GeV/c]

Charged ππππ,K,p : PRL91, 182301 (2003)ππππ0 : work in progress

√sNN = 200 GeV Au+Aucentrality : 0-92%

stat. error only

sys. error <15%

Collective flow Collective flow -- hydrodynamics hydrodynamics

! System behaves like a ! System behaves like a strongly interacting liquidstrongly interacting liquid (of low viscosity) !(of low viscosity) !

System is likely to be System is likely to be partonicpartonic, but not ‘plasma, but not ‘plasma--like’ (weakly interacting)like’ (weakly interacting)

In the bulk (low In the bulk (low ppTT) : ) : hydrodynamics works !hydrodynamics works !

(full hydro or (full hydro or blastwave parametrizationblastwave parametrization) )

• The complex behaviour of v2can be « simply » explained atpartonic level

… at intermediate pT !

Au+Au √sNN=200 GeV

STAR Preliminary

MinBias 0-80%

• Partonic flow• v2

s ~ v2u,d ~ 7%

Idea of flow per constituentflow per constituent – Coalescence/Recombination Elliptic flow developed atElliptic flow developed at partonicpartonic levellevel

Flow atFlow at partonicpartonic levellevel

Open and hidden charmOpen and hidden charm

Charm particlesCharm particlesCharm particles

‚Open‘ charm‚Open‘ charm

Mesons:

( ) ( )( ) ( )( ) ( )( ) ( )( ) ( )( ) ( )

GeV 1.864m

scDscD

scDscD

ucDucD

dcDdcD

ucDucD

dcDdcD

D

*

S

*

S

SS

0*0*

**

00

=

−+

−+

−+

−+

Baryons:Baryons:

( )( )

GeV 2.284m ...

udcΣ

udcΛ

C

C

=Λ

+

+

C

‚Hidden‘ charm‚Hidden‘ charm

( )( )( )( )( )

( )( )( )( )

...

2

1

0

4160

4040

MeV 37292m 3770

MeV 3685.92S

MeV 3556.21P

MeV 3510.51P

MeV 3415.01P

MeV 3096.81SJ/

MeV 2979.81S

D

Ψ

Ψ

=>Ψ

Ψ

Ψ

C

C

C

C

χχχ

η

mesonscc

DD

ee

hadrons

hadrons cc

:Decays

→Ψ

→ΨΨ

+Ψ→Ψ

+→

→

−+

)3770(

)'(J/

J/)'( γχγ

Anomalous J/Anomalous J/ΨΨΨΨΨΨΨΨ suppression in A+A suppression in A+A

Hidden charm: J/Hidden charm: J/ΨΨΨΨΨΨΨΨ , , ΨΨΨΨΨΨΨΨ‘:‘: Anomalous J/Anomalous J/ΨΨΨΨΨΨΨΨ suppression in A+A suppression in A+A

(NA38/NA50/NA60)(NA38/NA50/NA60)

Heavy flavor sectorHeavy flavor sector reflects the early dynamics since heavy hadrons can reflects the early dynamics since heavy hadrons can onlyonly

be formed in the very early phasebe formed in the very early phase of heavyof heavy--ion collisions !ion collisions !

J/J/ΨΨΨΨΨΨΨΨ ‚normal‘‚normal‘ absorption absorption by nucleons by nucleons

(Glauber model) (Glauber model)

Experimental observation:Experimental observation:

extra suppression in A+A collisions; extra suppression in A+A collisions;

increasing with centralityincreasing with centrality

There should be There should be ‚normal‘ nuclear absorption‚normal‘ nuclear absorption, ,

i.e. dissociation of charmonium by inelastic i.e. dissociation of charmonium by inelastic

interactions with nucleons of the interactions with nucleons of the

target/projectiletarget/projectile

CharmoniumCharmonium--N dissociation cross section can N dissociation cross section can

be fixed from p+A data be fixed from p+A data

I. Scenarios for charmonium suppression in A+AI. Scenarios for charmonium suppression in A+AI. Scenarios for charmonium suppression in A+A

•• I. QGP threshold meltingI. QGP threshold melting

[[Satz Satz et al’03et al’03]:]:

Charmonia suppression sets in abruptly at Charmonia suppression sets in abruptly at

threshold energy densities, where threshold energy densities, where χχCC and and

J/J/ΨΨ are melting are melting

Digal, Fortunato, Satzhep-ph/0310354; EPJ C32(2004) 547

χχχχχχχχC C meltingmelting

J/J/ΨΨΨΨΨΨΨΨ

•• QGP color screening: QGP color screening:

[Matsui and[Matsui and SatzSatz ’86]: ’86]: dissociation of dissociation of

charmonia in the deconfined mediumcharmonia in the deconfined medium: :

cc--cbar cannot form a bound state (J/cbar cannot form a bound state (J/ΨΨΨΨΨΨΨΨ) )

due to color screening in QGPdue to color screening in QGP

•• Regeneration of J/Regeneration of J/ΨΨΨΨΨΨΨΨ in QGP at Tin QGP at TCC::[Braun[Braun--Munzinger, Thews, Ko et al. `01]Munzinger, Thews, Ko et al. `01]

J/J/ΨΨΨΨΨΨΨΨ+g +g <<<<<<<<−−−−−−−−>>>>>>>> c+cbar+gc+cbar+g

•• However,However, lattice QCDlattice QCD predicts (2004): predicts (2004):

J/J/ΨΨΨΨΨΨΨΨ can exist up to ~2 Tcan exist up to ~2 TCC !!

QuarkoniumQuarkonium dissociation temperatures:dissociation temperatures:

II. Scenarios for charmonium suppression in A+AII. Scenarios for charmonium suppression in A+AII. Scenarios for charmonium suppression in A+A

0 20 40 60 80 100 120 1400

10

20

30

40

50

NA50 (2000):

anal. A

anal. B

anal. C

HSD

UrQMD

Bµ

µµ

µµ

µµµσσ σσ

(J/ ΨΨ ΨΨ

)/σσ σσ

(DY

)|2

.9-4

.5

Pb+Pb, 160 A GeV

ET [GeV]

•• II. Comover absorptionII. Comover absorption

[Gavin & Vogt, Capella et al.`97]:

charmonium absorption by low charmonium absorption by low

energy inelastic scattering with energy inelastic scattering with

‚comoving‘ mesons‚comoving‘ mesons (m=(m=π,η,ρ,...):π,η,ρ,...):π,η,ρ,...):π,η,ρ,...):π,η,ρ,...):π,η,ρ,...):π,η,ρ,...):π,η,ρ,...):

J/J/ΨΨΨΨΨΨΨΨ+m +m <<<<<<<<−−−−−−−−>>>>>>>> D+DbarD+Dbar

ΨΨΨΨΨΨΨΨ‘+m ‘+m <<<<<<<<−−−−−−−−>>>>>>>> D+DbarD+Dbar

χχχχχχχχCC+m +m <<<<<<<<−−−−−−−−>>>>>>>> D+DbarD+Dbar

+ + Charmonium recombination by Charmonium recombination by

DD--Dbar annihilation:Dbar annihilation:

5 10 15 20

10-8

10-7

10-6

10-5

10-4

10-3

tim e [fm/c]

J/ΨΨΨΨ +m ->D+D bar

D +D bar->J/ΨΨΨΨ +m

Pb+Pb, s1/2

=17.3 G eV , central

dN

/dt

5 10 15 20

10-4

10-3

10-2

10-1

time [fm/c]

J/ΨΨΨΨ+m->D+Dbar

D+Dbar->J/ΨΨΨΨ+m

Au+Au, s1/2

=200 GeV, central

dN

/dt

At At SPSSPS recreation of J/recreation of J/ΨΨΨΨΨΨΨΨ by D+Dbar by D+Dbar

annihilation is annihilation is negligiblenegligible

but at but at RHICRHIC recreation of J/recreation of J/ΨΨΨΨΨΨΨΨ by by

D+Dbar annihilation is D+Dbar annihilation is strongstrong!!

NNDDDD~16~16

I,II. Scenarios for charmonium suppression in A+AI,II. Scenarios for charmonium suppression in A+AI,II. Scenarios for charmonium suppression in A+A

•• QGP threshold melting as well as a comover absorption scenario QGP threshold melting as well as a comover absorption scenario areare

qualitativelyqualitatively consistentconsistent with exp. data (for In+In and Pb+Pb) at SPS energies with exp. data (for In+In and Pb+Pb) at SPS energies

•• Increase the energy: Increase the energy: new RHIC data new RHIC data atat

ss1/21/2=200=200 GeVGeV for Au+Aufor Au+Au: :

suppression at forwardsuppression at forward--rapidity is larger then rapidity is larger then

at midat mid--rapidities !rapidities !Nuclear modification factor:Nuclear modification factor:

0.0

0.5

1.0

PHENIX, |y|<0.35

PHENIX, 1.2<|y|<2.2

HSD

|y|<0.35

1.2<|y|<2.2

RA

A(J

/ ΨΨ ΨΨ)

Au+Au, s1/2

=200 GeV, QGP threshold scenario

+ recombination

D+Dbar<−><−><−><−> J/ΨΨΨΨ +m

without recombination

0 100 200 300

0.000

0.005

0.010

0.015

Bµ

µµ

µµ

µµµ( ΨΨ ΨΨ

') σσ σσ

ΨΨ ΨΨ' /

Bµ

µµ

µµ

µµµ(J

/ ΨΨ ΨΨ)

σσ σσJ

/ ΨΨ ΨΨ

Npart

0 100 200 300 400

Npart

QGP threshold melting scenario is ruled out by QGP threshold melting scenario is ruled out by PHENIX dataPHENIX data!!

J/J/Ψ Ψ Ψ Ψ Ψ Ψ Ψ Ψ and and ΨΨΨΨΨΨΨΨ´ suppression in Au+Au at RHIC: ´ suppression in Au+Au at RHIC:

(I.)(I.) QGP threshold melting scenarioQGP threshold melting scenario

Satz’s Satz’s model:model: complete dissociation of complete dissociation of

initial initial J/J/Ψ Ψ Ψ Ψ Ψ Ψ Ψ Ψ and and ΨΨΨΨΨΨΨΨ´ due to the huge local due to the huge local

energy densities ! energy densities !

CharmoniaCharmonia recombinationrecombination by Dby D--DbarDbar annihilationannihilation

is important, however, it can not generate enough is important, however, it can not generate enough

charmoniacharmonia, especially for peripheral collisions! , especially for peripheral collisions!

[Olena Linnyk et al.,[Olena Linnyk et al.,

arXivarXiv:070:0705.4443, 5.4443,

PRC 76 (2007) 041901 PRC 76 (2007) 041901 ]]

0.0

0.5

1.0 PHENIX, |y|<0.35

PHENIX, 1.2<|y|<2.2

Au+Au, s1/2

=200 GeV,

comover absorption

HSD

|y|<0.35

1.2<|y|<2.2

RA

A(J

/ ΨΨ ΨΨ)

0 100 200 300 400

0.000

0.005

0.010

0.015

D+Dbar<−><−><−><−> J/ΨΨΨΨ +m

Bµ

µµ

µµ

µµµ( ΨΨ ΨΨ

') σσ σσ

ΨΨ ΨΨ' /

Bµ

µµ

µµ

µµµ(J

/ ΨΨ ΨΨ)

σσ σσJ

/ ΨΨ ΨΨ

Npart

J/J/Ψ Ψ Ψ Ψ Ψ Ψ Ψ Ψ and and ΨΨΨΨΨΨΨΨ´ suppression in Au+Au at RHIC: ´ suppression in Au+Au at RHIC:

(II.) Comover absorption (+ recombination by D(II.) Comover absorption (+ recombination by D--Dbar annihilation)Dbar annihilation)

In the comover scenario the J/In the comover scenario the J/Ψ Ψ Ψ Ψ Ψ Ψ Ψ Ψ suppression at suppression at midmid--rapidityrapidity is is strongerstronger

thanthan at at forwardforward rapidity, rapidity, unlike the data!unlike the data!

Pure comover scenario is ruled out by Pure comover scenario is ruled out by PHENIX dataPHENIX data!!

-3 -2 -1 0 1 2 3

10-4

-3 -2 -1 0 1 2 3

10-4

central, 0-20%

Bµ

µµ

µµ

µµµ d

N(J

/ ΨΨ ΨΨ)/

dy

-3 -2 -1 0 1 2 310

-5

10-4

comover

PHENIX

Au+Au, s1/2

=200 GeV

HSD

semi-central, 20-40%

semi-peripheral, 40-60%

Bµ

µµ

µµ

µµµ d

N(J

/ ΨΨ ΨΨ)/

dy

y-3 -2 -1 0 1 2 3

10-6

10-5

y

peripheral, 60-90%

Olena Linnyk et al., Olena Linnyk et al.,

nuclnucl--th/0612049, NPA 786 (2007) 183; th/0612049, NPA 786 (2007) 183;

arXivarXiv::0801.4282, NPA 807 (2008) 79 0801.4282, NPA 807 (2008) 79

J/J/Ψ Ψ Ψ Ψ Ψ Ψ Ψ Ψ and and ΨΨΨΨΨΨΨΨ´ suppression in Au+Au at RHIC: ´ suppression in Au+Au at RHIC:

(III.) Pre(III.) Pre--hadronic interaction scenariohadronic interaction scenario

In the prehadronic interaction scenario the J/In the prehadronic interaction scenario the J/Ψ Ψ Ψ Ψ Ψ Ψ Ψ Ψ rapidityrapidity distributiondistribution has the right has the right

shape shape like the PHENIX data! => like the PHENIX data! => can can describe the describe the RHIC RHIC datadata atat ss1/21/2=200=200

GeVGeV for Au+Aufor Au+Au at at midmid-- and forwardand forward--rapidities simultaneouslyrapidities simultaneously..

Olena Linnyk et al., Olena Linnyk et al.,

arXivarXiv::0801.4282, NPA 807 (2008) 79 0801.4282, NPA 807 (2008) 79

-3 -2 -1 0 1 2 3

10-4

-3 -2 -1 0 1 2 3

10-4

central, 0-20%

Bµ

µµ

µµ

µµµ

dN

(J/ ΨΨ ΨΨ

)/d

y

-3 -2 -1 0 1 2 310

-5

10-4

comover

prehadron interactions

PHENIX

Au+Au, s1/2

=200 GeV

HSD

semi-central, 20-40%

semi-peripheral, 40-60%

Bµ

µµ

µµ

µµµ d

N(J

/ ΨΨ ΨΨ)/

dy

y-3 -2 -1 0 1 2 3

10-6

10-5

y

peripheral, 60-90%0 100 200 300 400

0.0

0.5

1.0

Au+Au, s1/2

=200 GeV

Prehadron interactions

PHENIX

|y|<0.35

1.2<|y|<2.2

Npart

HSD

|y|<0.35

1.2<|y|<2.2

RA

A(J

/ ΨΨ ΨΨ)

0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5-0.05

0.00

0.05

0.10

0.15

0.20

Au+Au, s1/2

=200 GeV

b=7 fm, 0<y<1

v2 (

pT)

PHENIX D+Dbar

J/ΨΨΨΨ

pT [GeV/c]

HSD: v2 of D+Dbar and J/ΨΨΨΨ from Au+Au versus pT and y at RHICHSD: vHSD: v22 of D+Dbar and J/of D+Dbar and J/ΨΨΨΨΨΨΨΨ from Au+Au versus pfrom Au+Au versus pTT and y at RHICand y at RHIC

• HSD:HSD: DD--mesons and J/mesons and J/Ψ Ψ Ψ Ψ Ψ Ψ Ψ Ψ follow the follow the

charged particle flow charged particle flow =>=>=>=>=>=>=>=> small vsmall v2 2 < 3%< 3%

•• STAR data STAR data show very show very large large collective collective

flow of Dflow of D--mesons mesons vv22~15%!~15%!

=> strong initial flow of => strong initial flow of

nonnon--hadronic nature!hadronic nature!

-6 -4 -2 0 2 4 60.00

0.01

0.02

0.03

0.04

0.05

0.06

PHOBOS

HSD

Au+Au, s1/2

=200 GeV

charge particles

v2( ηη ηη

)

ηηηη -2 -1 0 1 2

-0.02

0.00

0.02

0.04

0.06Au+Au, s

1/2=200 GeV

b=7 fm

v2 (

y)

D+Dbar

J/ΨΨΨΨ

y

Collective flow Collective flow

from from hadronic hadronic

interactionsinteractions is is

too low at too low at

midrapidity !midrapidity !

PRC 71 (2005) 044901PRC 71 (2005) 044901

D/DbarD/Dbar--mesons: inmesons: in--medium effectsmedium effects

•• Dropping DDropping D--meson massesmeson masses with with

increasing light quark density increasing light quark density

might give a might give a large enhancement of large enhancement of

the open charm yieldthe open charm yield at 25 A GeV ! at 25 A GeV !

FAIR (CBM)FAIR (CBM)

•• Charmonium suppression increasesCharmonium suppression increases

for dropping Dfor dropping D--meson masses! meson masses!

2.0 2.5 3.0 3.510

-8

10-6

10-4

10-2

__

D+D

bare

in-medium(2m

T)-1

dN

/dm

T [

GeV

-2]

Au+Au, 25 A GeV, central

mT [GeV]

Ch. SU(4):Ch. SU(4): A. Mishra et al., PRC69 (2004) 015202A. Mishra et al., PRC69 (2004) 015202

QCD sum rule:QCD sum rule: Hayashigaki, PLB487 (2000) 96Hayashigaki, PLB487 (2000) 96

Coupled channel:Coupled channel: Tolos et al., EPJ C43 (2005) 761Tolos et al., EPJ C43 (2005) 761HSD: NPA691 (2001) 761HSD: NPA691 (2001) 761

HSDHSD

0 1 2 3 4

1300

1400

1500

1600

1700

1800

QCD sum rule

Coupled

channel

Ch. SU(4) model:

MFT

RHA

D++++

D−−−−

mD

−− −− [M

eV]

ρρρρB/ρρρρ

0

0 1 2 3 4

1300

1400

1500

1600

1700

1800

1900

QCD sum rule

Ch. SU(4) model:

MFT

RHA

mD

+ [

MeV

]

∆ ∆ ∆ ∆ ∆ ∆ ∆ ∆ mmD D ((ρρρρρρρρ)= )= -- 50 (MeV) 50 (MeV) ρρρρρρρρ//ρρρρρρρρ00

Jet quenching and angular correlations Jet quenching and angular correlations

in A+Ain A+A

What is a jet?

Jet: A localized collection of hadrons which come from a fragmenting parton

c

chbbaa

abcd

ba

T

h

pp

z

Dcdab

td

dQxfQxfdxdxK

pdyd

d

πσσ 0

/22

2)(

ˆ),(),( →= ∑∫

Parton distribution Functions

Hard-scattering cross-section

Fragmentation Function

High pT (> ~2.0 GeV/c) hadron production in pp collisions:

b

a

c

d

Discovery of “Jet Quenching”Discovery of “Jet Quenching”Discovery of “Jet Quenching”

2 2/

AA bin pp

AA

T T

d N dR

dyd p dyd p

σ σ=

0

1

2

AAR

pT

Behavior of hard probesBehavior of hard probes

‘jet quenching’ ‘jet quenching’ –– inelastic and elastic scattering of theinelastic and elastic scattering of the partonspartons in in

the medium (the medium (partonicpartonic andand hadronichadronic))

Dynamics andDynamics and hadronizationhadronization mmechanismsechanisms

ησηddpdT

ddpNdpR

T

NN

AA

T

AA

TAA/

/)(

2

2

=

<<NNbinarybinary>/>/σσσσσσσσinelinelpp+p+p

nucleonnucleon--nucleonnucleon

cross sectioncross section

1. Compare Au+Au to nucleon1. Compare Au+Au to nucleon--nucleon cross sectionsnucleon cross sections

2. Compare Au+Au central/peripheral 2. Compare Au+Au central/peripheral

Nuclear Nuclear

Modification Modification

Factor:Factor:

If If no “effects”:no “effects”:

RRAAAA < 1 in regime of soft physics< 1 in regime of soft physics

(since soft physics scales with(since soft physics scales with NNpartpart

which is smaller thenwhich is smaller then NNbinarybinary))

RRAAAA = 1 at high= 1 at high--ppTT where hard where hard

scattering dominatesscattering dominates

Suppression:Suppression:

RRAAAA < 1 at high< 1 at high--ppT T “jet quenching”“jet quenching”

Also: Also: RRAAAA > 1 : Cronin Effect> 1 : Cronin Effect

AA

AA

AA

Nuclear Modification FactorNuclear Modification Factor

“Cronin effect”“Cronin effect”

Initial state multiple scatteringInitial state multiple scattering

leading to Cronin enhancement (Rleading to Cronin enhancement (RAAAA>1) >1)

JetJet--quenchingquenching(R(RAAAA<<1) 1)

AA

AA

AA

Nuclear Modification FactorNuclear Modification Factor

•• HighHigh ppTT enhancementenhancement in in

d+Au collisions at d+Au collisions at

√√ssNNNN=200=200 GeVGeV

•• Comparing Au+Au to Comparing Au+Au to d+Au atd+Au at midrapiditymidrapidity

⇒⇒⇒⇒⇒⇒⇒⇒ Strong effect of dense Strong effect of dense mediummedium

⇒⇒⇒⇒⇒⇒⇒⇒ PartonicPartonic energy lossenergy loss??

charged hadrons

Centrality DependenceCentrality Dependence

•• Dramatically different and opposite centrality evolution of Au+ADramatically different and opposite centrality evolution of Au+Au u experiment from d+Au control experiment.experiment from d+Au control experiment.

•• Jet suppression is clearly a final state effect of the dense medJet suppression is clearly a final state effect of the dense medium! ium!

Au + Au Experiment d + Au Control Experiment

Preliminary DataFinal Data

Cronin effect at RHIC (HSD)Cronin effect at RHIC (HSD)

Cronin effect:Cronin effect: initial state initial state semisemi--hard gluon radiationhard gluon radiation increases increases

ppTT spectra already in p+A or d+Aspectra already in p+A or d+A

Tpp

inelas

ppcoll

TdA

2event

dATdA

/dydpdσ/σN

/dydpNd1/N)(pR

⋅><⋅

=

W. Cassing, K. Gallmeister and C. Greiner, W. Cassing, K. Gallmeister and C. Greiner,

Nucl. Phys. A 735 (2004) 277Nucl. Phys. A 735 (2004) 277

Modelling of the Cronin effect Modelling of the Cronin effect

in HSD:in HSD:

<k<kTT22>>AAAA = <k= <kTT

22>>PPPP (1+a N(1+a NPrevPrev))

NNPrevPrev= number of previous = number of previous

collisionscollisions

parameter a = 0.25 parameter a = 0.25 –– 0.40.4 HSD without Cronin eff.

HSD with Cronin eff.

High pHigh pTT suppression in nonsuppression in non--central Au+Au (HSD)central Au+Au (HSD)

HSD with Cronin eff.

Cronin effect on Cronin effect on ππππππππ, K, K++ mmTT--spectra in A+A (HSD)spectra in A+A (HSD)

•• Very small effect at Very small effect at

AGSAGS

•• Hardening of the mHardening of the mTT

spectra at top SPSspectra at top SPS

•• Substantial Substantial

hardening of the mhardening of the mT T

spectra at RHIC spectra at RHIC ––> >

large improvement ! large improvement !

•• Consistent with other Consistent with other

observables !observables !

0.0 0.5 1.0 1.5 2.0 2.5

10-1

100

101

102

103

mT

-1 d

N/(

dm

Td

y)

[(G

eV)-2

]m

T

-1 d

N/(

dm

Td

y)

[(G

eV)-2

]

K−−−−*0.1

K+

Au+Au, s1/2

=200 GeV, 5%, midrapidityππππ−−−−

mT

-1 d

N/(

dm

Td

y)

[(G

eV)-2

]

0.0 0.2 0.4 0.6 0.8 1.0

10-2

10-1

100

101

102

103

K−−−−*0.1

K+

Pb+Pb, 160 A GeV, 5%, midrapidity

ππππ−−−−

0.0 0.2 0.4 0.6 0.8 1.0

10-2

10-1

100

101

102

103

default

with Cronin effect

HSD with Cronin effect

K−−−−*0.1

K+

Au+Au, 11 A GeV, 5%, midrapidityππππ−−−−

mT-m

0 [GeV]

PRC 69 (2004) 015202PRC 69 (2004) 015202

Different Ways to “Skin a Jet”Different Ways to “Skin a Jet”

1) Integral Distributions:1) Integral Distributions:

<<ppTT>, <>, <NNchch>>

2) Single Particle Spectra:2) Single Particle Spectra:

ddσσσσσσσσ//dpdpTT ⇒⇒⇒⇒⇒⇒⇒⇒ RRAAAA,, RRdAdA

3) 23) 2--Particle Correlations:Particle Correlations:

dNdN/d(/d(∆φ∆φ∆φ∆φ∆φ∆φ∆φ∆φ))

4) Jet Reconstruction:4) Jet Reconstruction:

ddσσσσσσσσ//dEdETT ,, FragFrag.. FuncFunc..

triggertrigger

“Trigger”

φφφφ = 0Adler et al., PRL90:082302 (2003), STAR

near-side

awayaway--sideside

Jet Energy LossJet Energy Loss

High pT particle

p+p

High pT particle

Au+Au

away

near

Coll

imat

edre

gio

n

away

QGP suppression ?!QGP suppression ?!

Jet suppression: dN/dJet suppression: dN/dϕϕϕϕϕϕϕϕ (HSD)(HSD)

•• The jet angular The jet angular

correlations for correlations for pppp are are

fine !fine !

•• The nearThe near--side jet side jet

angular correlation for angular correlation for

central Au+Au is well central Au+Au is well

described, but the described, but the

suppression of the farsuppression of the far--

side jet is too low side jet is too low !!

STAR

HSD

(pre(pre--)hadronic FSI)hadronic FSI

QGP suppressionQGP suppression

W. Cassing, K. Gallmeister, C. Greiner, W. Cassing, K. Gallmeister, C. Greiner,

J.Phys.G30J.Phys.G30 (2004) (2004) S801S801;; NPA 748 (2005) 41NPA 748 (2005) 41

New exp. data: New exp. data: φφφφφφφφ−−−−−−−−ηηηηηηηη angular correlationsangular correlations

6262

φ∆

-3-2

-10

12

3

η∆-1.5

-1-0.5

00.5

11.5

#e

ntr

ies

65

70

75

80

310×

STAR

Eur.Phys.J.C61 (2009) 569-574

PHOBOS

Phys.Rev.Lett.104 (2010) 062301

I: High I: High ppTT particle correlations in HSD vs. STAR dataparticle correlations in HSD vs. STAR data

STAR: High pT:

pT(trig) > 4 GeV/c

2 < pT(assoc) < 4 GeV

Au+AuAu+Au

p+pp+p

HSD vs. STAR: HSD vs. STAR:

••away side structureaway side structure is suppressed in Au+Au collisions is suppressed in Au+Au collisions in comparison to p+p,in comparison to p+p,

however, HSD however, HSD doesndoesn‘‘t providet provide enough high penough high pTT suppressionsuppression to to reproduce the reproduce the

STARSTAR Au+Au dataAu+Au data

••nearnear--sideside ridge structure is NOT seen ridge structure is NOT seen in HSD!in HSD!

RealReal--Mixed distributionMixed distribution

φ∆

-3-2

-10

12

3

η∆-1.5

-1-0.5

00.5

11.5

#e

ntr

ies

65

70

75

80

310×

STAR

V. Konchakovski V. Konchakovski

1.5

1.0

0.5

0.0

-0.5

0.0

0.2

0.4

0.6

0.8

1.0

-4

-2

0

2

real - mixed

1/N

trig dN

/dη

dφ

∆η

∆φ/π

00.040.080.120.160.200.240.280.320.360.400.440.480.520.560.60

II: Intermediate II: Intermediate ppTT particle correlations in HSD vs. PHOBOS dataparticle correlations in HSD vs. PHOBOS data

PHOBOS: Intermediate pT:

pT(trig) > 2.5 GeV/c; 0.02 < pT(assoc) < 2.5 GeV

Au+AuAu+Au

p+pp+p

PHOBOSPHOBOS

HSD vs. PHOBOS: HSD vs. PHOBOS:

••away side structureaway side structure is suppressed in Au+Au collision in comparison to p+p, is suppressed in Au+Au collision in comparison to p+p,

however, HSD however, HSD doesndoesn‘‘t providet provide enough high penough high pTT suppressionsuppression to to reproduce reproduce

the PHOBOS Au+Authe PHOBOS Au+Au datadata

••nearnear--sideside ridge structure is NOT seen ridge structure is NOT seen in HSD!in HSD!

RealReal--Mixed distributionMixed distribution

V. KonchakovskiV. Konchakovski

The QGP is observed at RHIC !The QGP is observed at RHIC !

The phase diagram of QCDThe phase diagram of QCD

0 200 400 600 800 1000 1200

0

50

100

150

200

250

endpoint

(2+1 flavor lattice QCD)

[Fodor, Katz '04]

phase boundary

chemical freezout

[Cleymans et al.]

endpoint

(3 flavor lattice QCD)

[Karsch et al., QM'04]

endpoint

(2+1 flavor lattice QCD)

[Fodor, Katz '02]

UrQMD:

Au+Au, 11 A GeV

Pb+Pb, 40 A GeV

Pb+Pb, 160 A GeV

Au+Au, 21300 A GeV

µµµµB [MeV]

T [

MeV

]

• UrQMD initial energy UrQMD initial energy

density is density is higherhigher than the than the

boundary from LQCDboundary from LQCD

••TriTri--critical point reached critical point reached

somewhere between 20 somewhere between 20

and 30 A GeVand 30 A GeV

•• we are probing awe are probing a new new

phase of matter phase of matter already atalready at

AGS! AGS!

OutlookOutlook

The QuarkThe Quark--GluonGluon--Plasma is there!Plasma is there!

But what are the But what are the properties properties of this of this

phase ?!phase ?!

Initial idea (1970 Initial idea (1970 –– 2003):2003):

QGP is a weakly interacting QGP is a weakly interacting

gas of colored but almost massless gas of colored but almost massless

quarks and gluonsquarks and gluons

State of the art 2010:State of the art 2010:

QGP is a strongly interacting QGP is a strongly interacting

and almost ideal and almost ideal „„color liquidcolor liquid““ !!

New phase diagram of QCDNew phase diagram of QCD

A. Peshier, W. Cassing, PRL (2005) A. Peshier, W. Cassing, PRL (2005)

0 200 400 600 800 1000

10

100

1000

nonperturbative colored parton gas

colored parton liquid

endpoint

[Fodor, Katz '04]

chemical freezout

[Cleymans et al.]

UrQMD:

Au+Au, 11 A GeV

Pb+Pb, 40 A GeV

Pb+Pb, 160 A GeV

Au+Au, 21300 A GeV

µµµµB [MeV]

T [

MeV

]