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collective and hard phenomena @RHIC&LHC within an unified transport description. C. Greiner, Obergurgl, february 2011. in collaboration with: I.Bouras, A. El, O. Fochler, F. Reining, J. Uphoff, C. Wesp, Zhe Xu. - PowerPoint PPT Presentation
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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