Diapositive 1

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CERN HEAVY ION FORUM
14 October 2005
Bulk Observables in Nucleus-Nucleus collisions
Christian KUHN (Strasbourg), Luciano RAMELLO
(Alessandria)
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Hard-soft correlations
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F. Wang / J. Ulery STAR
Hard-soft angular correlations
pTtrig4-6 GeV/c pTassoc0.15-4 GeV/c

• Broader away-side correlations in central AuAu,
  softer pT -gt partial thermalisation
• Novel dip at p in away ltpTgt for pTtriglt6 GeV/c.
  Associated hadrons at p appear more equilibrated.

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Intermediate pT trigger Intermediate pT
partner
Clear signal of broadening of away-side jet with
increasing centrality Clear signal of dip
structure in away-side jet increasing with
increasing centrality
Henner Buesching PHENIX
D
D
D
Splitting Parameter D
PHENIX preliminary
hadron-hadron
Splitting Parameter D increasing with
centrality Similar trend for all systems and
energies
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In the same conditions
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Sonic boom from quenched jets ?
hep-ph/0411315 Casalderrey-Solana,Shuryak,Teaney n
ucl-th/0406018 Stoecker Hep-ph/0503158
Muller,Ruppert
The energy deposited by jets into liquid-like
strongly coupled QGP must go into conical shock
waves
Other effects ?
nucl-th/0507063 Koch, Majumder, X.-N. Wang
Cherenkov gluon radiation
hep-ph/0411341 Armesto,Salgado,Wiedemann
Correlation of jet with flowing medium
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3-particle correlations Mach cone ?
Normal Jet
Mach cone
Characteristics ridges
Bent Jet
Au-Au 10ltcentlt20 V2 subtracted
PHENIX Preliminary
Compatible with expected features of Mach cone
N.N. Ajitanand PHENIX
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Strong flavor dependence
J. Ulery STAR
N.N. Ajitanand PHENIX
dAu min-bias
Hadron-Meson-Meson
difference in AuAu average signal per
radian2 center corner 0.3 0.3 (stat)
0.4 (syst) center cone 2.6 0.3 (stat)
0.8 (syst)
PHENIX Preliminary
dAu and AuAu elongated along diagonal
Distinctive features of conical flow are not
seen in the data with these pT windows.
Hadron-Baryon-Baryon
AuAu 10 cent
PHENIX Preliminary
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Event characterization dNch/d?, scaling
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dNch/d?, energy density
P. Staszel BRAHMS
Energy density Bjorken 1983 eBJ 3/2 ?(ltEtgt/
pR2t0) dNch/d? assuming formation time
t01fm/c gt 5.0 GeV/fm3 for AuAu _at_ 200 GeV gt
4.4 GeV/fm3 for AuAu _at_ 130 GeV gt 3.7 GeV/fm3 for
AuAu _at_ 62.4 GeV
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Scaling laws (PHOBOS)
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Extended longitudinal scaling
G. Veres
Energy independence in a large h range...
in a centrality dependent way.
Nucl. Phys. A 757 28 (2005)
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Longitudinal scaling described byColor Glass
Condensate
G. Veres
Phys.Rev.C70 027902 (2004)
Nucl. Phys. A 757 28 (2005)
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Elliptic flow
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Elliptic flow at RHIC
H. Masui PHENIX
Large v2 of heavier particles (f, X, W, d)
and open charm (single electrons) -gt strong
interactions at early stage. Large v2 of f, X, W
(low hadronic x-sections) -gt partonic
collectivity at RHIC.
F. Wang / X. Cai / M. Oldenburg / J. Speltz STAR
Hydro works suggests early thermalization.
Soft (QGP) EOS favored sub-hadronic DOF.
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?? Elliptic Flow _at_ SPS
C. Hoehne NA49
Significant v2 CERES and NA49 in good
agreement
Hydro with Tf 120 MeV reproduce pT spectra but
overpredict v2 SPS data Predictions with Tf 160
MeV closer to v2 data but cant reproduce pT
spectra
Weaker increase of v2(pT) at SPS than at
RHIC
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Elliptic Flow in AuAu and CuCu
V. Greene / H. Masui PHENIX
G. Wang STAR
PHOBOS 200 GeV h 0-40- centrality
PHOBOS 200 GeV h 0-40- centrality
Smaller v2 in CuCu than in AuAu
Multiple methods to remove non-flow 4-particle
cumulants, subtraction of pp,
G. Roland PHOBOS
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System size and eccentricity
S. Manly PHOBOS
Standard eccentricity (?standard)
Fluctuations in eccentricity are important in
Cu-Cu
This is evidence that ?part is (close to) the
relevant eccentricity for driving the azimuthal
asymmetry

• Expect ltv2gt/lt?gt constant
• for system at hydro limit.

Participant eccentricity (?part)
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Scaling properties to test ideal fluid
R.A. Lacey
Scaling PHENIX Data
PHENIX Preliminary
5ltCentralitylt30
yT sinh-1(pT / m)
From hydro
V2 a k x yT2 m

• Unequivocal scaling at low values

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Coalescence (recombination) / fragmentation
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Recombination/fragmentation model (S. Bass et
al.) systematic deviation from quark number
scaling in v2, predicted from inclusion of gluons
and sea quarks, observed (at 5 level) (P.
Sorensen)
Coalescence (recombination) versus fragmentation
M. D. Oldenburg STAR
v2 appears to scale with number of constituent
quarks. Quark coalescence
(deconfinement)
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Rcp and baryon/meson ratio
J. Dunlop STAR
M. Lamont STAR
Reco./ Frag. Model (S. Bass et al.)
Baryon / meson ratio Transition to
common Rcp at pT 6 GeV/c.
But it does still not explain intrinsic angular
correlations (J.Ulery). Morever parameterizations
appear to be inconsistent with dynamical models
(hydro, parton cascades,) space-time
inhomogeneities, large local momentun
anisotropies, -gt D. Molnar

• Promising start made in the Df
• away side by simulating parton
• re-scattering and absorption
• (C.Hwa)

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Baryon/meson Npart
V.Greene PHENIX
Coalescence / recombination also reproduces
qualitatively the Npart dependence of B/M
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RCP
S. Salur STAR
RAA
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Chemical freeze-out Strangeness
enhancement Kinetic freeze-out Resonances
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Chemical freeze-out
hadron-chemistry particle ratios ? chemical
freeze-out properties
J. Speltz STAR
Tch
STAR white paper Nucl Phys A757 (05) 102
short lived resonances
short lived resonances
gs
gs
STAR white paper Nucl Phys A757 (05) 102
Tch TC 165 10 MeVChemical freeze-out
hadronization Chemical equilibration
and saturation of strangeness
See poster J. Speltz (164)
Non-eq. stat. model fits (gs gt2) also describe
well the data
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Energy Dependence of L, X Enhancement
100
Redlich et al., JPG28 (2002) 2095
Canonical suppression increases with decreasing
energy Not clear between 8.8 GeV and 17.2 GeV
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X-
A. Dainese NA57
Enhancements are the same or even bigger at
RHIC than at SPS !
Other scaling Npart ? dNch/d? correlated to
the entropy of the system ?
S. Salur STAR
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S. Salur STAR
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Do s-quarks have different scaling ?

• The more strangeness you add the less it scales
  with Npart.

H. Caines STAR
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Kinetic freeze-out
Particle spectra ? kinetic freeze-out properties,
total collective radial flow
Blast wave fit
A. Dainese NA57

• p,K,p, L Tkin decreases, bT increases with
  centrality. Early decoupling in peripheral
  collisions?
• X, W (low hadronic x-sections) higher Tkin ( -gt
  Tch at 200 GeV). Early decoupling but still
  significant radial flow -gt partonic ?

F. Wang, S. Salur, J. Speltz STAR
X, W lt?Tgt at 200 GeV 62 GeV Tkin at
200 GeV gt 62 GeV
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Single freezeout model
BW models do not take into account effect of
resonances -gt low Tkin (100 MeV) Cracow
Single-Freeze-Out Model Broniowski and
Florkowski, PRL 87, 272302 (2001) radical
simplification chemical and kinetic freeze-out
coincide all resonances included, emission
function includes (all) cascading decays
absolute yields predicted
Parameters at 200 GeV T 165.5 MeV, µ_B 28.5
MeV
W. Florkowski
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How to interpret Tkin ?
BW models do not take into account the effect of
resonances -gt low Tkin (100 MeV) Alternative
description of the spectra Single freeze-out
model (chemical and thermal freeze-out
coincide) Include all set of resonances or pion
Interactions -gt Tkin Tchem
J. Speltz STAR
W. Florkowski
Tkin from a blast-wave fit is not the same as
the kinetic freeze-out temperature from a Hydro
Model.
Single freeze-out or not ?
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Hydro-inspired model BUDA-LUND
BUDA-LUND model Csanad, Csörgõ, Lörstad, and
Ster, J. Phys. G30, S1079 (2004) compared to
BRAHMS and PHENIX AuAu data at 130, 200 GeV
Decoupling happens at T 100-120 MeV, a hot
center with T 200 MeV, is considered as a
signal/remnant of the decon?ned phase
W. Florkowski
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HBT puzzle ?
R. Lednicky
Hydro assuming ideal fluid explains strong
collective (?) flows at RHIC but not the
interferometry results
Bass, Dumitru, ..
But comparing
11D HydroUrQMD
11D HUrQMD
Huovinen, Kolb, ..
21D Hydro
with 21D Hydro
Hirano, Nara, ..
? kinetic evolution
3D Hydro
? not enough ?t
conserves Rout,Rlong
increases Rside
at small pt
(resonances ?)
? Good prospect
for Hirano .. 3DH
hadron transport
author
? initial ?t
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Resonances
Resonance decay, re-scattering of daughters and
regeneration
time
Ratio to stable particle in AuAu / pp
information on behaviour and timescale between
chemical and kinetic freeze-out
Finite time span from chemical to kinetic
freeze-out, constant for different
centralities Cross sections and lifetimes vary
(K vs L)
S. Salur STAR
Re-scattering and regeneration is required to
model resonance production
Regeneration s(K) gt s(L)
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??KK measurement
Chiral symmetry restoration ?
A. Kozlov PHENIX
dn/dy for F?ee- tends to be larger than for F?KK
F?KK line shape and mass are flat (and
consistent with PDG values) within errors as
functions of Npart
But large errors
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Low-mass ee mass spectrum

• Toia PHENIX

Almost final results from the 2000 run PbAu at
158 GeV per nucleon
Rapp-Wambach r broadening
Brown-Rho scaling r mass shift
D. Miskowiec CERES

• No significant enhancement above cocktail
• Systematic errors (S/B) too large to distinguish
  between vacuum r spectral function and
  theoretical calculations including chiral
  symmetry restoration

Enhancement over hadron decay cocktail for mee gt
0.2 GeV 2.43?0.21 (stat) for 0.2 GeVltmeelt 0.6
GeV 2.8?0.5 (stat)
Syst. 21
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Low-mass dimuons
E. Scomparin NA60
Mass shift of the ? (Brown-Rho) ruled out
CSR ??
Mass resolution23 MeV at the ? position
Clear excess (wrt all cocktail sources) of low
mass. Increase with centrality
?, ? and even ? peaks clearly visible in dimuon
channel
Excess shape consistent with broadening of the ?
(Rapp-Wambach)
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Event by Event observables
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Pt and multiplicity fluctuations
C. Hoehne NA49
all negatives, acceptance 4 lt yp lt 5.5 and 0.005
lt pt lt 1.5 GeV/c
NA49 preliminary
NA49, PRC 70, 034902 (2004)

• fluctuations increase towards peripheral
  collisions
• consistent with percolation picture
  fluctuations expected for systems where several
  clusters are present Ferreiro et al., PRC 69,
  034901 (2004)
• ltptgt and multiplicity fluctuations correlated
• Mrowczynski et al, PRC 70, 054906 (2004)

similar results at RHIC, e.g. PHENIX, PRL 93,
092301 (2004)
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Multiplicity fluctuationsvs. collision overlap
geometry
T. Nakamura PHENIX
When plotted as a function of a measure of the
collision overlap geometry (fractional impact
parameter divided by the nuclear diameter - so a
head-on collision 1.0), the 62 GeV CuCu
fluctuations are less Poissonian.
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F-B mult. Correlations in AuAu (PHOBOS)
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(No Transcript)
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Net charge fluctuations
C.A. Pruneau STAR
Koch/Jeon QGP -3.

• Magnitude of net charge compatible with
  resonance and coalescence models finite
  centrality dependence but note dN/d?/(Npart/2)
  changes with Npart.