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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**
qqqq
gggg
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
]
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