Collective phenomena in midcentral heavy ion collisions

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Collective phenomena inmid-central heavy
ioncollisions

• A. Herghelegiu, C. Andrei, I. Berceanu,
• M. Petrovici, A. Pop, C. Schiaua

• ALICE-Workshop, August 20-24, 2008,
• Sibiu - Romania

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Overview

• Elliptic flow a very short review
• Geometrical considerations other effects
• Results - Mean pt azimuthal distribution
• Conclusions

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What should be expected as a function of incident
energy ?
4 AGeV
lt 100 AMeV
100 AMeV - 600 AMeV

• The experimental evidences

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a2 excitation function
Squeeze-out ratio
A.Andronic, G.Stoicea, M.Petrovici FOPI Coll.
N.P.A679(2001)765
C.Pinkenburg EOS Coll. Phys.Rev.Lett.
83(1999)1295
H.H. Gutbrod Plastic Ball Coll
Phys.Rev.C 42(1990)640
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Mean kinetic energy azimuthal distributions
G.Stoicea, M.Petrovici FOPI
Phys.Rev.Lett. 92(2004)072303
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Ecoll T azimuthal distributions
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BUU transport model predictions
Pawel Danielewicz approach
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Fireball shape shadowing effects
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v2 excitation function
A.Andronic FOPI Coll. Phys.Lett. B612(2005)173
FOPI Z1 particles EOS,E895 protons E877
all charged particles CERES all charged
particles NA49 pions
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Elliptic Flow - Quark Number Scaling
PHENIX
nucl-ex/0608033
PRL 92 (2004) 052302 PRL 91 (2003) 182301

• At the moment of hadronization in
  nucleus-nucleus
• collisions at RHIC the dominant degree of
  freedom
• is related to number of constituent
  (valence) quarks
• These constituent quarks exhibit an angular
• anisotropy resulting from collective
  interactions
• Hadrons seem to be formed from coalescence or
• recombination of the constituent quarks

nucl-ex/0703024
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Other effects to be considered
Angular momentum conservation
Glauber model
F.Becattini et al nucl-th/0711.1253
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Other effects to be considered
Core Corona effects
K.Werner PRL 98(2007)152301
1/2pmtdn/dydmt/Ncoll
mt-m
PbPb 17.3 GeV
multiplicity/participant
total
core
participant number Np
1/Npdn/dy (renorm.)?
participant number Np
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Geometrical considerations
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Expectations/predictions for LHC
Parton recombination approach
D.Krieg et al nucl-th/0708.3015
N.Borghini et al hep-ph /0707.0564
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Simulations
input (MC)
output (ESD)? HIJING Collision
Geometry (b,?RP) in header CG in ZDC
NO FLOW but AfterBurnerFlow
tracks GevSim Multiplicity, ?RP,
tracks
Flow -gt v2 parametrization

PbPb _at_ 5.5TeV ? lt 0.9
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Results - HIJING
p
K
p
p-
K-
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pt spectra azimuthal distribution - HIJING
pions kaons protons
Reconstructed Simulated
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Mass dependance of ltpTgt - HIJING
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Results - GevSim
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pT spectra azimuthal distribution - GevSim
pions kaons protons
Reconstructed Simulated
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ltptgt azimuthal distribution - GevSim
pions kaons protons
Simulated Reconstructed
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v2pt mass dependance - GevSim
ltptgt pt0 (1v2pt cos2(f-?RP))?
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Conclusions
Based on the experience at lower energies, ltptgt
(ltEKINTgt) azimuthal distributions seems to be
sensitive probes for detailed diagnosis of
fireball dynamics in mid central
collisions. The mean pt reconstruction seems to
be feasible in the phase space covered by central
barrel for primary pion kaons and protons. The
extension of such analysis to multi-strange
barions and J/? is aimed for the near future.
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Thank You! Questions?