collective and hard phenomena @RHIC&LHC

within an unified transport description

in collaboration with:

I.Bouras, A. El, O. Fochler, F. Reining, J. Uphoff, C. Wesp, Zhe Xu

- early thermalization, viscosity and elliptic flow- dissipative shock waves and Mach Cones- jet quenching … same phenomena?- charming probes

C. Greiner, Obergurgl, february 2011

by S.Bass

Hot Plasma:Quark-Gluonic Medium

Freeze-Out & Hadronisation:Hadronic medium

Decoupling:Observation in a detector

time

Schematic picture of HIC:

Initial production of partons

dt

dpxfxpxfxK

dydydp

d cdab

tbtadcbat

jet

),(),( 2

222

11,;,21

2

minijets

string matter

color glass condensate

),(),(),( pxCpxCpxfp ggggggggg

BAMPS: Boltzmann Approach of MultiParton Scatterings

A transport algorithm solving the Boltzmann-Equations for on-shell partons with pQCD interactions

new development ggg gg,radiative „corrections“

(Z)MPC, VNI/BMS, AMPT

Elastic scatterings are ineffective in thermalization !

Inelastic interactions are needed !

Xiong, Shuryak, PRC 49, 2203 (1994)Dumitru, Gyulassy, PLB 494, 215 (2000)Serreau, Schiff, JHEP 0111, 039 (2001)Baier, Mueller, Schiff, Son, PLB 502, 51 (2001)

BAMPS: Z. Xu and C. Greiner, PRC 71, 064901 (2005);Z. Xu and C. Greiner, PRC 76, 024911 (2007)

)cosh()(

12

)(2

9

,)(2

9

222

22

222

242

222

242

ykmqkk

qg

mq

sgM

mq

sgM

gLPM

DDggggg

Dgggg

J.F.Gunion, G.F.Bertsch, PRD 25, 746(1982)T.S.Biro at el., PRC 48, 1275 (1993)S.M.Wong, NPA 607, 442 (1996)

screened partonic interactions in leading order pQCD

),3(16),( 1)2(

223

3

qfgppd

sDD fnftxmm

screening mass:

LPM suppression: the formation time g1 cosh

yk

g: mean free path

radiative part

elastic part

suppressed!

Stochastic algorithm P.Danielewicz, G.F.Bertsch, Nucl. Phys. A 533, 712(1991)A.Lang et al., J. Comp. Phys. 106, 391(1993)

for particles in 3x with momentum p1,p2,p3 ...

collision probability:

23321

3232

32323

32222

)(823

32

22

x

t

EEE

IPfor

x

tvPfor

x

tvPfor

rel

rel

)()2(2)2(2)2(2

1'2'1321

)4(42

'2'1123'2

3'2

3

'13

'13

32 pppppME

pdE

pdI

cell configuration in space

3x

Heavy-ion collision at LHCBAMPS simulation of QGP phase at LHC at sNN = 2.76 TeV

Visualization framework courtesy MADAI collaboration, funded by the NSF under grant# NSF-PHY-09-41373

3-2 + 2-3: thermalization! Hydrodynamic behavior! 2-2: NO thermalization

simulation pQCD 2-2 + 2-3 + 3-2simulation pQCD, only 2-2

at collision center: xT<1.5 fm, z < 0.4 t fm of a central Au+Au at s1/2=200 GeVInitial conditions: minijets pT>1.4 GeV; coupling s=0.3

pT spectra

time scale of thermalization

0

2

2

02

2

2

2

2

2

exp)()(tt

E

pt

E

p

E

pt

E

peq

ZZeq

ZZ

= time scale of kinetic equilibration.

fm/c 5.0Theoretical Result !

gg gg: small-angle scatterings

gg ggg: large-angle bremsstrahlung

distribution of collision angles

at RHIC energies

Transport Rates

trggggg

trggggg

trgggg

trdrift RRRR

1

Z. Xu and CG, PRC 76, 024911 (2007)

ggggggggggggggi

vn

Cpd

vCvpd

R

z

iziztri

,,

,)

31

(

)2()2( with

2

3

322

3

3

• Transport rate is the correct quantity describing kinetic equilibration.

• Transport collision rates have an indirect relationship to the collision-angle distribution.

trggggg

trggggg

trgggg

trggggg

RR

R

R

3

2

53

Transport Rates

2222 )(ln~: sstrRgggg

01.0for)(ln~: 2223 ssstrRggggg

01.0for)(ln~ 2323 ssstrR

Large Effect of 2-3 !

ggggggggg

mb 0.57

mb 0.82

MeV 400T,3.0 for s

ggggg

gggg

Shear Viscosity

)3(2

2

uu

TTT

zz

zzyyxx

Navier-Stokes approximation

322323

31

31

1)(

5

1

2

2

2

2

RRR

En

tr

E

p

E

p

z

z

relation: <-> Rtr

Z. Xu and CG,

Phys.Rev.Lett.100:172301,2008.

RHIC

AdS/CFT

yux

xy

numerical extraction of viscosity - I

>νμ<μνeq

μνμν uη=TT=π 2

Starting from a classical ansatz

x

vη=

A

F zz

With the Navier-stokes approximaion

F. Reining

xL

v=vz 2

tanh2tanh max

velocity profile

finite size error

rt,ππrddtTVk

=η xyxy

B

0,0

10

1 3

VTπ

=π xy

52 4

0,0

GeVfm

τT

π=

s

η

0.19720

1

τtπ=rt,ππ xyxyxy /exp0,00,0 2

C. Wesp

Green-Kubo relation:

equilibrium fluctuations:

numerical extraction of viscosity - II

C. Wesp

some examples

numerical extraction of viscosity - II

0.130.3 23 ==αsη

s

C. Wespnumerical extraction of viscosity - II

0.070.6 23 ==αsη

s

perturbative small viscosity …

1.040.3 22 ==αs

ηs

Motion Is Hydrodynamic

x

yz

• When does thermalization occur? – Strong evidence that final state bulk behavior

reflects the initial state geometry

• Because the initial azimuthal asymmetry persists in the final state dn/d ~ 1 + 2 v2(pT) cos (2) + ...

2v2

Elliptic Flow and Shear Viscosity in 2-3 at RHIC 2-3 Parton cascade BAMPS Z. Xu, CG, H. Stöcker, PRL 101:082302,2008

viscous hydro.Romatschke, PRL 99, 172301,2007

322323

31

31

1)(

5

1

2

2

2

2

RRR

En

tr

E

p

E

p

z

z

/s at RHIC: 0.08-0.2

Rapidity Dependence of v2: Importance of 2-3! BAMPS

evolution of transverse energy

B. Betz, M. Gyulassy, D. Rischke, H. Stöcker, G. Torrieri

Mach Cones in Ideal Hydrodynamics

Box Simulation

QCD “sonic boom”

22

Medium

jet

T = 400 M eV

E jet=200 GeV

Box scenario, no expansion of the medium, massless Boltzmann gasinteractions: 2 2 with isotropic distribution of the collision angle

Mach Cones in BAMPS

Setup

Jet has constant mean free path and onlymomentum in z-direction!

fmGeV=dxdE / 1411/

Mach Cones in BAMPS:Different Viscosities

E jet=200 GeVη / s=0.005

The results agree qualitatively with hydrodynamic and transport calculations→ B. Betz, PRC 79:034902, 2009 Strong collective behaviour is observed A diffusion wake is also visible, momentum flows in direction of the jet

o

jet

s

v

c=θ 54.7arccos

Mach Cones in BAMPS:Different Viscosities

E jet=200 GeVη / s=0.025

Mach Cones in BAMPS:Different Viscosities

E jet=200 GeVη / s=0.08

Mach Cones in BAMPS:Different Viscosities

E jet=200 GeVη / s=0.32

The shock front (Mach front) gets broader and vanish with more dissipation The viscosity smears the profile out, but does it affect the Mach angle?

Stoped Jet in BAMPS:

0.025/

GeV 20

=sη

=E jet

Stoped Jet in BAMPS:

0.08/

GeV 20

=sη

=E jet

Stoped Jet in BAMPS:

0.2/

GeV 20

=sη

=E jet

.50/

GeV 20

sη

=E jet

Stoped Jet in BAMPS:

nuclear modification factor

relative to pp (binary collision scaling)

experiments show approx. factor 5 of suppression in hadron yields

Hard probes of the medium

high energy particles are promising probes of the medium created in AA-collisions

QM 2008, T. Awes

LPM-effect transport model: incoherent treatment of ggggg processes parent gluon must not scatter during formation time of emitted gluon

discard all possible interference effects (Bethe-Heitler regime)

kt

CM frame

p1 p2

lab frame

kt

= 1 / kt

total boost

O. Fochler

Energy Loss in gg ggg Processes

Reasonable partonic cross sections over the whole energy range. Definition of the energy loss E matters

E = Ein – max( Eiout )

E =

Cross sections ( T = 400 MeV) Energy loss in single gg ggg

Gluon Radiation and Energy Loss

Heavy tail in E distribution leads to large mean <E>

Radiaton spectrum (E = 50 GeV) E distribution (E = 400 GeV)

Some BAMPS Events (CM frame)

E = 0.67 GeV E = 206.43 GeV

E = 26.01 GeV E = 117.01 GeV

RAA ~ 0.052

cf. S. Wicks et al.Nucl.Phys.A784, 426

nuclear modification factorcentral (b=0 fm) Au-Au at 200 AGeVO. Fochler et al

Quenching of jetsfirst realistic 3d results with BAMPS

PRL102:202301:2009

inclusion of light quarks is

mandatory !

… lower color factor

jet fragmentation scheme

O. Fochler, Z. Xu and C. Greiner, PRC82:024907 (2010)

Non-Central RAA

and High-pT Elliptic Flow

Gluonic RAA for b = 0 and b = 7 fm

Differential v2 for b = 7 fm

Experimental v2 from PHENIX, arXiv: 0903.4886

Quenching of jetspreliminary

Rates for quarks and gluons are roughly the same!

quark jet in gluon jet conversion

… needs more analysis

Binary processes – RAA

and v2?

10 mb, isotropic 2->2: v

2 is still to low

10 mb, isotropic 2->2: jet quenching is already to strong

Sensitivity on the LPM Cut-Off

RAA

for different X (b = 7 fm) v2 for different X (b = 7 fm)

Zhe Xu, Jaipur, Quark Matter 2008

η / s=0.13

full pQCD Jet

const isotropic scenario

η / s=0.13

charming probes

D

cc_

D_

Pre-equil. phase

QGPD

D

D

D

J/ψJ/ψ

e

c

c

c

Initial hard

parton scatterin

gs

Energy loss

J/ψ regenera

tion

J/ψ dissociat

ion

D

D

cCharm

production

c_

c_

c_

c_

Heavy flavor in BAMPS

Jan Uphoff, Fochler, Xu, GreinerPhys. Rev. C 82 (2010)

Initial charm in hard parton scatterings

1. LO pQCD: mini-jets

2. NLO pQCDDistributions from R. Vogt

3. PYTHIAMonte Carlo Event Generatorfor nucleon-nucleon collisions

Three approaches:

both very sensitive on•parton distribution functions•factorization scale •renormalization scale•charm mass

Charm production in the QGP at RHIC

BAMPS

ccggccgg K J. Uphoff et al.,arXiv:1003.4200 [hep-ph]

RHICRHIC

maximum of 3.4 pairsare produced

Charm production in the QGP at LHC

BAMPS

LHCLHC

Large secondary production→ Can even be comparable to initial production

November run

Elliptic flow v2 for charm at RHIC

J. Uphoff et al., arXiv:1004.4091 [hep-ph]only elastic charm processes

gQgQgQgQ K

PHENIX, arXiv:1005.1627

Heavy quark elliptic flow v2 at RHIC

A. Peshier, arXiv:0801.0595 [hep-ph]

P.B. Gossiaux, J. Aichelin,Phys.Rev.C78 (2008)

Jan Uphoff

can be fixed to

by comparing dE/dx to HTL result beyond logarithmic accuracy

Heavy quark elliptic flow v2 at RHIC

gQgQgQgQ K

PHENIX, arXiv:1005.1627only elastic processes considered

Impact of hadronization and decay small

Peterson fragmentation

Heavy quark RAA at RHIC

gQgQgQgQ K

only elastic heavy quark processesPHENIX, arXiv:1005.1627

Heavy quark elliptic flow v2 and RAA at LHC

gQgQgQgQ K

only elastic heavy quark processes

LHCLHC

J/ψ production

preliminary

J/ψ production

preliminary

Inelastic/radiative pQCD interactions (23 + 32) explain:

fast thermalization

large collective flow

small shear viscosity of QCD matter at RHIC

realistic jet-quenching of gluons

Summary

Future/ongoing analysis and developments:

light and heavy quarks

jet-quenching (Mach Cones, ridge)

p+p physics (initial state fluctuations)

hadronisation and afterburning (UrQMD) needed to determine

how imperfect the QGP at RHIC and LHC can be

… and dependence on initial conditions

dissipative hydrodynamics

BAMPS Group

Zhe Xu and Carsten Greiner:Heads and Supervisors + Administrator

Oliver Fochler:Investigation of Jet-Quenching, Code maintanance of BAMPS,

Andrej El:Comparison of viscous hydro to BAMPS

Jan Uphoff:Including heavy quarks

Felix Reining and Christian Wesp:Extracting shear viscosity from BAMPS using different Ansatz

Ioannis Bouras:Investigation of shocks and Mach Cones in BAMPS,Comparison to viscous hydro

F. Lauciello, B. Linnik, A. Meistrenko and F. Senzel:Master students

Semiclassical kinetic theory?

Weak or strong ….Validity of kinetic transport - relation to shear viscosity

Quantum mechanics: quasiparticles?

A.El, Z. Xu and CG, Nucl.Phys.A806:287,2008.

ggg gg !This 3-2 is missing in the Bottom-Up scenario(Baier, Dohkshitzer, Mueller, Son (2001)).

Initial conditions: Color Glass Condensate Qs=3 GeV; coupling s=0.3

pT spectra

Bottom up is not working as advocated: no tremendous soft gluon production,soft modes do not thermalize before the hard modes

… and adding quarks as further degrees of freedom

quarks are helping in the right direction …

Z. Xu and C. Greiner, Phys.Rev.C81:054901,2010

Inclusion of Light Quarks