Recent%20Results%20from%20the%20NA49%20Experiment

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Recent Results fromthe NA49 Experiment
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Heavy Ion Physics at the CERN SPSExploring the
QCD Phase Diagram

• SPS energy regime allows to explore an
  essential part of the phase diagram
• Chemical freeze-out points approach phase
  boundary at SPS energies
• Transition to QGP is likely to happen in
  this region
• Ebeam 20 - 158 AGeV (?sNN 6.3
  - 17.3 GeV)
• Use hadronic observables to pin down phase
  transition
• Systematic studies required
• ? Energy dependence

Lattice calculations Fodor and
Katz Bielefeld-Swansea group Hadron gas fits J.
Manninen et al.
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Heavy Ion Physics at the CERN SPS The NA49
Experiment
Particle identification Pions, charged
Kaons dEdx in TPCs TOF (mid-rapidity) K0s, ?,
?, ? Decay topology invariant
mass ? Invariant mass of identified Kaons
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Heavy Ion Physics at the CERN SPSParticle
Identification in NA49

• dE/dx measured in TPCs
• Large acceptance
• Resolution 3-4
• Time-of-flight
• Mid-rapidity
• Resolution 60 ps

Example PbPb _at_ 40 AGeV
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Outline

• What are the properties of the matter created at
  SPS?
• New data for top SPS energy (?sNN 17.3 GeV)
• High-pt spectra for identified particles
• Elliptic flow of Lambdas
• Can a phase transition possibly be located?
• Energy dependence of hadronic observables
• Rapidity spectra
• Particle yields
• Transverse mass spectra

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High pt SpectraMeasurement of Identified
Particles
PbPb (23.5) pt 3.6 - 4.0 GeV/c
?
Parton energy loss observable? Parton
recombination?
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High pt SpectraBaryon-Meson Ratio
Baryon-Meson ratio larger than 1 at higher
pt Similar to what has been observed at RHIC
NA49 very preliminary
PbPb, 158 AGeV
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High pt SpectraRCP for Identified Particles _at_
?sNN 17.3GeV
NA49 very preliminary
PbPb, 158 AGeV
RCP for charged pions close to 1 for pt gt 1.5
GeV/c ? No Cronin enhancement for pions!
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Elliptic Flowv2 for Pions
Initial spatial anisotropy ? different pressure
gradients ? momentum anisotropy v2
Mid-rapidity data, pt integrated
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Elliptic Flowv2 for Pions, Protons, and Lambdas
Linear increase of v2 with pt for all particle
species Clear mass hierarchy v2(?) gt v2
(p) gt v2(?) Blast wave fits reproduce data quite
well T 90 MeV, ??? 0.5 Model F.
Retiere and M. Lisa, Phys. Rev. C70 (2004),
044907
NA49 data on pions and protons C. Alt et al.,
Phys. Rev. C68 (2003), 034903.
PbPb, 158 AGeV
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Elliptic Flowv2 for Lambdas SPS and RHIC
pt dependence seems to be weaker at SPS than at
RHIC Partially due to different centrality
selection
? Initial pressure not too different to RHIC
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Rapidity Spectra
Central PbPb 7 (20-80) 5/10 (158) NA49
Change of shape only for L Others
Gaussians
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Rapidity SpectraEnergy Dependence of Widths
Pion widths are close to Landau prediction, but
not perfectly
But Perfect agreement to linear dependence on
ybeam
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Rapidity SpectraEnergy Dependence of Widths
Linear dependence on ybeam (works up to RHIC !)
Clear hierarchy for Gaussian-like particles at
SPS (p, ?, ? excluded) ? gt K gt K-, ? gt
? Seems to break down at AGS
NA49 preliminary
? Thermal component of longitudinal flow
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Rapidity SpectraDependence on Strangeness Content
Central PbPb, 158 AGeV NA49
Net protons 3 valence quarks (uud )
Net ?s 2 valence (ud ) 1 produced quark (s )
Net ?s 1 valence (d ) 2 produced quarks
(ss )
Omegas 3 produced quarks (sss )
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Particle YieldsAntibaryon-Baryon Ratio
Energy dependence weakens with increasing
strangeness content
NA49 preliminary
Lines Statistical hadron gas model J. Manninen
et al. Fit to 4? data!
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Particle YieldsAntilambda-Antiproton Ratio
Increase above 1 towards lower energies consisten
t with recent NA49 data
NA49 preliminary
Models predict ratio lt 1
Hadron Gas 1 J. Manninen et al. Hadron Gas 2 K.
Redlich et al.
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Particle Yields
AGS
NA49
BRAHMS
Central AuAu, PbPb
4? multiplicities only!
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Particle YieldsEnergy Dependence
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Particle YieldsEnergy Dependence
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Particle YieldsEnergy Dependence
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Particle YieldsEnergy Dependence
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Particle YieldsComparison s- and s-Carriers
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Particle Yields(Anti-)Strangeness to Pion Ratio
Difficult to model Solid line Statistical
hadron gas model with ?s 1 K. Redlich, priv.
comm. Predicted as signal for the onset of
deconfinement M. Gazdzicki and M.I. Gorenstein,
Acta Phys. Polon. B30 (1999), 2705
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Transverse Mass SpectraEnergy Dependence of
?mt?-m0
? negatively charged
Energy dependence of transverse activity seems to
change around 30 AGeV. General feature for
pion, kaons and protons
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Transverse Mass SpectraInverse Slope Parameters
of Kaons
Y. Hama et al. Braz. J. Phys. 34 (2004), 322,
hep-ph/0309192
Feature cannot be described by transport models
Hydro calculation with assumption of 1st order
phase transition
? Change of EOS seen?
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Summary

• Matter created at top SPS energy qualitatively
  similar to what is observed at RHIC
• Chemical freeze-out close to phase boundary
• High pt baryon meson ratio gt 1
• No Cronin enhancement in pion RCP
• Substantial elliptic flow (?, p, ?)
• Systematic study of energy dependence
• Mass dependence of rapidity widths, seemingly
  independent of beam energy at SPS
• Maximum in the strangeness to pion ratio at 30
  AGeV ? Evidence for deconfinement?
• Clear change of the energy dependence of
  mt-spectra at 30 AGeV ? Evidence
  for a change of EOS?

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The NA49 Collaboration

• C. Alt, T. Anticic, B. Baatar, D. Barna, J.
  Bartke, L. Betev, H. Bialkowska,
• C. Blume, B. Boimska, M. Botje, J. Bracinik, R.
  Bramm, R. Brun, P. Buncic,
• V. Cerny, P. Christakoglou, O. Chvala, J.G.
  Cramer, P. Csató, P. Dinkelaker,
• V. Eckhardt, D. Flierl, Z. Fodor, P. Foka, V.
  Friese, J. Gál, M. Gazdzicki,
• V. Genchev, G. Georgopoulos, E. Gladysz, K.
  Grebieszkow, S. Hegyi,
• C. Höhne, K. Kadija, A. Karev, M. Kliemant, S.
  Kniege, V.I. Kolesnikov,
• E. Kornas, R. Korus, M. Kowalski, I. Kraus, M.
  Kreps, M. van Leeuwen,
• P. Lévai, L. Litov, B. Lungwitz, M. Makariev,
  A.I. Malakhov, M. Mateev,
• G.L. Melkumov, M. Mitrovski, J. Molnár, S.
  Mrowczynski, V. Nicolic, G. Pálla,
• A.D. Panagiotou, D. Panayotov, A. Petridis, M.
  Pikna, D. Prindle, F. Pühlhofer,
• R. Renfordt, C. Roland, G. Roland, M. Rybczynski,
  A. Rybicki, A. Sandoval,
• N. Schmitz, T. Schuster, P. Seyboth, F. Siklér,
  B. Sitar, E. Skrzypczak,
• G. Stefanek, R. Stock, H. Ströbele, T. Susa, I.
  Szentpétery, J. Sziklai,
• P. Szymanski, V. Trubnikov, D. Varga, M.
  Vassiliou, G.I. Veres,
• G. Vesztergombi, D. Vranic, A. Wetzler, Z.
  Wlodarczyk, I.K. Yoo,
• and J. Zimányi

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The End
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Particle YieldsStatistical Hadron Gas Model
Becattini et al., Phys. Ref. C69 (2004) 024905
Assumption of chemical equilibrium at the
freeze-out point
? Particle production can be described with a
few parameters V, T, ?B, ?s
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Elliptic FlowComparison to Hydro Model
Data below hydro calculation with Tf120MeV
Hydro calculation by Pasi Huovinen
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Particle YieldsEnergy Dependence
Central PbPb/AuAu
Mid-rapidity ratios
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Particle YieldsEnergy Dependence
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Transverse Mass SpectraInverse Slope Parameters
of Kaons
Step in energy dependence
Seems to be absent in pp
How about other particle types?
pp compilation from M. Kliemant, B. Lungwitz,
and M. Gazdzicki, PRC 69 (2004) 044903