slide1 n.
Download
Skip this Video
Loading SlideShow in 5 Seconds..
in collaboration with: I.Bouras, A. El, O. Fochler, F. Reining, J. Uphoff, C. Wesp, Zhe Xu PowerPoint Presentation
Download Presentation
in collaboration with: I.Bouras, A. El, O. Fochler, F. Reining, J. Uphoff, C. Wesp, Zhe Xu

Loading in 2 Seconds...

play fullscreen
1 / 59

in collaboration with: I.Bouras, A. El, O. Fochler, F. Reining, J. Uphoff, C. Wesp, Zhe Xu - PowerPoint PPT Presentation


  • 108 Views
  • Uploaded on

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.

loader
I am the owner, or an agent authorized to act on behalf of the owner, of the copyrighted work described.
capcha
Download Presentation

PowerPoint Slideshow about 'in collaboration with: I.Bouras, A. El, O. Fochler, F. Reining, J. Uphoff, C. Wesp, Zhe Xu' - harper-mckay


An Image/Link below is provided (as is) to download presentation

Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author.While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server.


- - - - - - - - - - - - - - - - - - - - - - - - - - E N D - - - - - - - - - - - - - - - - - - - - - - - - - -
Presentation Transcript
slide1

collective and hard phenomena @RHIC&LHCwithin 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

  • early thermalization, viscosity and elliptic flow
  • dissipative shock waves and Mach Cones
  • jet quenching … same phenomena?
  • charming probes
slide2

Schematic picture of HIC:

by S.Bass

time

Hot Plasma:

Quark-Gluonic Medium

Freeze-Out & Hadronisation:

Hadronic medium

Decoupling:

Observation in a detector

initial production of partons
Initial production of partons

minijets

color glass condensate

string matter

slide4

BAMPS: BoltzmannApproachofMultiPartonScatterings

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)

slide5

screened partonic interactions in leading order pQCD

elastic part

radiative part

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)

screening mass:

LPMsuppression: the formation time

Lg: mean free path

suppressed!

slide6

P.Danielewicz, G.F.Bertsch, Nucl. Phys. A 533, 712(1991)

A.Lang et al., J. Comp. Phys. 106, 391(1993)

Stochastic algorithm

cell configuration in space

D3x

for particles in D3x with momentum p1,p2,p3 ...

collision probability:

heavy ion collision at lhc
Heavy-ion collision at LHC

BAMPS 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

slide8

pT spectra

at collision center: xT<1.5 fm, Dz < 0.4 t fm of a central Au+Au at s1/2=200 GeV

Initial conditions: minijets pT>1.4 GeV; coupling as=0.3

simulation pQCD 2-2 + 2-3 + 3-2

simulation pQCD, only 2-2

3-2 + 2-3: thermalization!

Hydrodynamic behavior!

2-2: NOthermalization

slide9

time scale of thermalization

Theoretical Result !

t = time scale of kinetic equilibration.

slide10

distribution of collision angles

at RHIC energies

gg gg: small-angle scatterings

gg ggg: large-angle bremsstrahlung

slide11

Transport Rates

  • Transport rate is the correct quantity describing kinetic
  • equilibration.
  • Transport collision rates have an indirect relationship
  • to the collision-angle distribution.

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

slide12

Transport Rates

Large Effect of 2-3 !

slide13

Z. Xu and CG,

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

Shear Viscosity h

Navier-Stokes approximation

relation: h <-> Rtr

AdS/CFT

RHIC

slide14

numerical extraction of viscosity- I

F. Reining

Starting from a classical ansatz

With the Navier-stokes approximaion

velocity profile

finite size error

slide15

numerical extraction of viscosity- II

C. Wesp

Green-Kubo relation:

equilibrium fluctuations:

slide17

numerical extraction of viscosity- II

C. Wesp

perturbative small viscosity …

motion is hydrodynamic

z

y

x

Motion Is Hydrodynamic
  • When does thermalization occur?
    • Strong evidence that final state bulk behavior reflects the initial state geometry
  • Because the initial azimuthal asymmetrypersists in the final statedn/df ~ 1 + 2v2(pT) cos (2 f) + ...

2v2

slide19

Elliptic Flow and Shear Viscosity in 2-3 at RHIC

2-3Parton cascade BAMPS

Z. Xu, CG, H. Stöcker, PRL 101:082302,2008

viscous hydro.

Romatschke, PRL 99, 172301,2007

h/s at RHIC: 0.08-0.2

slide22

Mach Cones in BAMPS

Setup

jet

Jet has constant mean free path and only

momentum in z-direction!

Medium

Box scenario, no expansion of the medium, massless Boltzmann gas

interactions: 2  2 with isotropic distribution of the collision angle

slide23

Mach Cones in BAMPS:

Different Viscosities

  • 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
slide24

Mach Cones in BAMPS:

Different Viscosities

slide25

Mach Cones in BAMPS:

Different Viscosities

slide26

Mach Cones in BAMPS:

Different Viscosities

  • 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?
hard probes of the medium
Hard probes of the medium
  • nuclear modification factor

relative to pp (binary collision scaling)

  • experiments show approx. factor 5 of suppression in hadron yields

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

QM 2008, T. Awes

lpm effect

transport model: incoherent treatment ofggggg processes

  • parent gluon must not scatter during formation time of emitted gluon
    • discard all possible interference effects (Bethe-Heitler regime)

p1

p2

kt

kt

lab frame

CM frame

t = 1 / kt

  • total boost
LPM-effect

O. Fochler

energy loss in gg ggg processes
Energy Loss in gg  ggg Processes

Cross sections ( T = 400 MeV)

Energy loss in single gg  ggg

  • Reasonable partonic cross sections over the whole energy range.
  • Definition of the energy loss DE matters
    • DE = Ein – max( Eiout )
    • DE = w
gluon radiation and energy loss
Gluon Radiation and Energy Loss

Radiaton spectrum (E = 50 GeV)

DE distribution (E = 400 GeV)

  • Heavy tail in DE distribution leads to large mean <DE>
some bamps events cm frame
Some BAMPS Events (CM frame)

DE = 0.67 GeV

DE = 206.43 GeV

DE = 26.01 GeV

DE = 117.01 GeV

slide36

Quenching of jets

first realistic 3d results with BAMPS

RAA ~ 0.052

cf. S. Wicks et al.

Nucl.Phys.A784, 426

nuclear modification factor

central (b=0 fm) Au-Au

at 200 AGeV

O. Fochler et al

PRL102:202301:2009

non central r aa and high p t elliptic flow
Non-Central RAA and High-pT Elliptic Flow

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

Gluonic RAA for b = 0 and b = 7 fm

Differential v2 for b = 7 fm

  • inclusion of light quarks is mandatory !
  • … lower color factor
  • jet fragmentation scheme

Experimental v2 from PHENIX,arXiv:0903.4886

quenching of jets
Quenching of jets

preliminary

  • Rates for quarks and gluons are roughly the same!
  • quark jet in gluon jet conversion
  • … needs more analysis
binary processes r aa and v 2
Binary processes – RAA and v2?

10 mb, isotropic 2->2: v2 is still to low

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

slide40

Sensitivity on the LPM Cut-Off

RAA for different X (b = 7 fm)

v2 for different X (b = 7 fm)

charming probes
charming probes

Heavy flavor in BAMPS

e

D

_

D

Initial hardpartonscatterings

D

D

D

c

Energyloss

Charmproduction

c

c

D

J/ψdissociation

J/ψregeneration

c

J/ψ

Pre-equil. phase

c

QGP

D

J/ψ

D

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

_

_

_

_

_

c

c

c

c

c

initial charm in hard parton scatterings
Initial charm in hard parton scatterings

Three approaches:

LO pQCD: mini-jets

NLO pQCDDistributions from R. Vogt

PYTHIAMonte Carlo Event Generatorfor nucleon-nucleon collisions

  • both very sensitive on
  • parton distribution functions
  • factorization scale
  • renormalization scale
  • charm mass
charm production in the qgp at rhic
Charm production in the QGP at RHIC

RHIC

charm pairs

BAMPS

maximum of 3.4 pairs

are produced

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

charm production in the qgp at lhc
Charm production in the QGP at LHC

charm pairs

BAMPS

LHC

November run

Large secondary production

→ Can even be comparable to initial production

elliptic flow v 2 for charm at rhic
Elliptic flow v2 for charm at RHIC

PHENIX,

arXiv:1005.1627

J. Uphoff et al., arXiv:1004.4091 [hep-ph]

only elastic charm processes

heavy quark elliptic flow v 2 at rhic
Heavy quark elliptic flow v2 at RHIC

Jan Uphoff

can be fixed to

by comparing dE/dx to HTL result beyond logarithmic accuracy

A. Peshier, arXiv:0801.0595 

[hep-ph]

P.B. Gossiaux,

J. Aichelin,Phys.Rev.C78 (2008)

slide49

Heavy quark elliptic flow v2 at RHIC

Peterson fragmentation

  • Impact of hadronization and decay small

PHENIX,

arXiv:1005.1627

only elastic processes considered

heavy quark r aa at rhic
Heavy quark RAA at RHIC

PHENIX,

arXiv:1005.1627

onlyelastic heavy quarkprocesses

heavy quark elliptic flow v 2 and r aa at lhc
Heavy quark elliptic flow v2 and RAA at LHC

LHC

onlyelastic heavy quarkprocesses

j production
J/ψ production

preliminary

slide53

J/ψ production

preliminary

slide54

Summary

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

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
slide55

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

slide56

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

Semiclassical kinetic theory?

Quantum mechanics: quasiparticles?

slide57

pT spectra

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

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)).

Bottom up is not working as advocated:

no tremendous soft gluon production,

soft modes do not thermalize before the hard modes

slide58

… and adding quarks as further degrees of freedom

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

quarks are helping in the right direction …