Outline

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Outline

• First of all, theres too much data!!
• Focus on some recent results and analyses
• BRAHMS
• PHOBOS
• PHENIX
• STAR
• Low, Intermediate, High-pt
• Can we understand it? Can at least some of it be
  synthesised?
• Spectra
• Flow

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Particle Spectra in AuAu, STAR ylt.5

• Hydro inspired Thermal Fits (input to
  Blast-Wave parameterization) (T, bt) (170 MeV,
  0.6c) Large transverse flow component in central
  collisions.

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Hydrodynamics ? Equation of State

• Low pt, 99.5 of particles are below 2 GeV.

Hydrodynamics describes bulk particle momentum
distributions

Hydro is limit of zero mean free pathearly phase
dominated by strong interactions? Calculations ?
too long a system lifetime (still work to
do) Enormous initial pressure, but decouples
quickly (10 fm/c)
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Spectra at large y, BRAHMS.
y3
Radial flow decreases at large rapidity. Boost
invariant region is only about 1 unit wide! 3-D
hydro
y0 Thermal fit ?T 0.53 T 138. MeV
y3 Thermal fit ?T 0.42 T 140 MeV
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Charged hadrons at large h, PHOBOS
T. Hirano
Hydrodynamics Mid-rapidity data is well
described, but larger rapidity is not.
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Particle Ratios and Statistical Models
Statistical models do a very good job. Values Tch
are very close to expected Tcrit from
lattice. However, this alone cannot prove a
phase transition nor that the system is thermal
but coupled with agreement from hydrodynamics
(spectra and v2), evidence starts to increase
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Intermediate pt, spectra for various masses
Yield of p (L) similar to p(K) at 3 GeV, flow
effect for heavier particle/baryon?
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Compare with scaling by Ncoll

• K0s and p0 show suppression at 2-3 GeV, p and L
  do not strong radial flow for heavier particles?

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Particles with Similar Mass

• Differ at low pt, similar at 3 GeV
• Reflection of Flow? Rescattering? Recombination?
• Rescattering has effect on other observables
  resonances! (See Patricias talk)

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Wealth of data!

• It is very important to try to understand as much
  of the combined measurements as possible
• Under a single framework!
• Many times, predictions work for observable A but
  fail for observable B. Need a coherent picture!
• Some recent ideas
• Hydro-inspired Blast-wave (wont go into it)
• RecombinationFragmentation
• Single Freeze-out

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Fragmentation Recombination
Lopez, Parikh, Siemens, PRL 53 (1984) 1216 Net
charge and baryon number fluctuations Asakawa,
Heinz, BM, PRL 85 (2000) 2072 Jeon, Koch, PRL 85
(2000) 2076 Balance functions Bass,
Danielewicz, Pratt, PRL 85 (2000)
2689 Recombination / coalescence Fries, BM,
Nonaka, Bass, nucl-th/0301087 Greco, Ko, Levai,
nucl-th/0301093 Molnar, Voloshin,
nucl-th/0302014
Bass et al. nucl-th/0306027
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FR Model assumptions

• at low pt, quarks and antiquarks recombine into
  hadrons locally at an instant
• hadron momentum P is much larger than average
  momentum ??p2? of the internal quark wave
  function of the hadron
• features of the parton spectrum are shifted to
  higher pt in the hadron spectrum
• parton spectrum has thermal part (quarks) and a
  power law tail (quarks and gluons) from pQCD.

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Does it fit the measured spectra?
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For identified particlesp, K
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p, f, L, X, W
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Ratios vs pt
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High pt suppression.
Reproduces charged hadron suppression, and flavor
dependence. Prediction, quenching for protons
above 6 GeV, where fragmentation starts to
dominate
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What about v2?
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Does v2 reflect partonic flow?
See also Lin Ko, PRL 89 (2002) 202302 Molnar
Voloshin, nucl-th/0302014
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Identified Particle Spectra at RHIC _at_ 200 GeV
BRAHMS 10 central PHOBOS 15 PHENIX 5 STAR
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Feed-down matters !!!
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Single freeze-out model, Tch Tkin?
Very nice feature, include feeddown in the
calculations. Describe spectra and ratios vs pt
and vs centrality well Supports the use of
thermal approach to heavy ion collisions If
TchTkin, very explosive expansion!
W. Broniowski and W. Florkowski, PRC 65 064905
(2002), for 130 GeV A. Baran, W. Broniowski, W.
Florkowski nucl-th/0305075 for 200 GeV ratios and
spectra.
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High-pt Latest news from the dAu run
From cover of PRL 91 (2003) 072302 Phobos 072303
Phenix 072304 Star 072305 Brahms

• In AuAu, suppression of high-pt hadrons and of
  away side jet, not seen in dAu. Final state
  effectconsistent with the production of dense
  matter!!

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Summary Conclusions

• All 4 RHIC experiments have continued their
  outpour of measurements.
• Low pt spectra, hydrodynamic fits, statistical
  models taken together yield support (albeit dont
  prove) to a high density thermalized phase.
• Still trouble in the longitudinal direction (HBT,
  v2 vs y)
• We are beginning to see more theoretical efforts
  that encompass various observables! That is good!
• Spectra, flow, correlations. Would like to
  understand in one picture, pt, y and centrality
  dependence.
• Fragmentation Recombination aplicability of
  the recombination regime to 3-6 GeV,
  fragmentation dominates at a higher pt than one
  naïvely expected.
• v2 of hadrons reflects v2 of constituent quarks
  (? and !)
• High-pt spectra and correlations suppression of
  hadrons and away-side jet is a final state effect.