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Review of Structures in the Energy Dependence of Hadronic Observables Christoph BlumeInt. Workshop on Critical Point and Onset of Deconfinement Florence, July 3-6, 2006
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Christoph Blume Florence, July 3-6 2006 2 Introduction Exploring the QCD Phase Diagram Cross over Critical point Lattice calculations: Fodor and Katz Bielefeld-Swansea group Hadron gas fits ( ): J. Manninen et al. 1st order Chemical freeze-out points approach phase boundary at SPS energies Transition to QGP likely to happen in this region E beam = 20 - 158 AGeV ( s NN = 6.3 - 17.3 GeV)
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Christoph Blume Florence, July 3-6 2006 3 Introduction Energy Dependence Any evidence for a phase transition (or the even critical point) in hadronic observables seen ? Look for “non-smooth” behaviour in the energy dependencies Prominent examples: “horn”, “kink”, “step” Any other structures? How significant are they? Comparison to hadronic models Transport models (UrQMD + HSD) Statistical models Identify “trivial” structures Baseline comparison
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Christoph Blume Florence, July 3-6 2006 4 Introduction Hadronic Scenery at SPS J. Cleymans, H. Oeschler, K. Redlich, and S. Wheaton, hep-ph/0510283 Transition from baryon dominated to meson dominated system Statistical model: Transition at s NN 8 GeV Maximum of strangeness prod. Evidences for structures beyond this?
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Christoph Blume Florence, July 3-6 2006 5 Introduction ”Horn” / “Kink” / “Step” K + + / N w HORN KINK STEP
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Christoph Blume Florence, July 3-6 2006 6 Introduction Experiments AGS SPS RHIC ExperimentsE beam (A GeV) s nn (GeV)SystemParticles AGS E802, E866, E877, E891, E895, E917 2-10.72.7-4.9Au+Au , K, p, SPS NA45, NA49, NA57, (NA44, WA98) 20-1586.3-17.3Pb+Pb , K, p, , , , ,... RHIC STAR, PHENIX, BRAHMS, PHOBOS -20.0-200.0Au+Au , K, p, , , , ,...
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Christoph Blume Florence, July 3-6 2006 7 Introduction Observables Particle yields Pions Strangeness Transverse mass spectra Radial flow EOS Elliptic flow Initial pressure Bose-Einstein correlations System size and lifetime Not discussed here: Fluctuations
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Christoph Blume Florence, July 3-6 2006 8 Particle Yields Energy Dependence of Particle Ratios K + / + K - / - / / - / - + + / UrQMD + HSD E.L. Bratkovskaya et al., PRC 69 (2004), 054907 Statistical hadron gas: P. Braun-Munzinger, J. Cleymans, H. Oeschler, and K. Redlich Nucl. Phys. A697 (2002) 902 s = 1 Full chem. equilibrium baseline
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Christoph Blume Florence, July 3-6 2006 9 Particle Yields Comparison to Statistical Model (data – model)/ (data) Statistical hadron gas: P. Braun-Munzinger, J. Cleymans, H. Oeschler, and K. Redlich Nucl. Phys. A697 (2002) 902 Kaons and deviate from stat. model for s NN 7-8GeV ? ? Different situation for hyperons s = 1
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Christoph Blume Florence, July 3-6 2006 10 Particle Yields Position of Maxima Ratio Maximum at s NN (GeV) K+/+K+/+ 10.8 // 5.1 -/+-/+ 10.2 -/+-/+ 27.0 Statistical model prediction: J. Cleymans, H. Oeschler, K. Redlich, and S. Wheaton, hep-ph/0510283
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Christoph Blume Florence, July 3-6 2006 11 Particle Yields Local Slope of Energy Dependence: and K No significant structure for pions Indications for sudden changes in kaon e.-dependence (?)
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Christoph Blume Florence, July 3-6 2006 12 Particle Yields Comparison s- and s-Carriers s-quark carriers: K -, K 0 (1) (incl. 0 ) 0,-, - (2) ± (3) s-quark carriers: K +, K 0 (1) (incl. 0 ) 0,+, + (2) ± (3) (1) K 0 K + , K 0 K - by isospin symmetry (2) Taken from hadron gas fit by Becattini et al., if not measured. (3) Empirical factor ( + ) / = 1.6 assumed. Data: E802, E866, E895, E917, NA49 1.5 ( + + - ) Sudden change of strangeness production at s NN = 7-8GeV ?
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Christoph Blume Florence, July 3-6 2006 13 Particle Yields Local Slope of Energy Dep.: s/s-Quarks Local slope seems to change quite fast for strangeness at s NN = 7-8GeV Smoother dependence for pions
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Christoph Blume Florence, July 3-6 2006 14 Particle Yields (Anti-)Strangeness to Pion Ratio Maximum in strangeness/pion ratio Same for s and s quarks Difficult to model in hadronic scenarios Solid line: Statistical hadron gas model with s = 1 K. Redlich, priv. comm. Predicted as signal for the onset of deconfinement Dotted line: M. Gazdzicki and M.I. Gorenstein, Acta Phys. Polon. B30 (1999), 2705
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Christoph Blume Florence, July 3-6 2006 15 Transverse Mass Spectra Energy Dependence of m t -m 0 Energy dependence of transverse activity seems to change around s NN = 7-8GeV General feature for pion, kaons and protons Quite robust observation negatively charged
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Christoph Blume Florence, July 3-6 2006 16 Transverse Mass Spectra Local Slope of Energy Dependence: m t -m 0 Significant change of local slope for pions and kaons around s NN = 7 GeV Similar for protons
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Christoph Blume Florence, July 3-6 2006 17 Elliptic Flow Energy Dependence of v 2 for Pions Initial spatial anisotropy different pressure gradients momentum anisotropy v 2 Mid-rapidity data, p t integrated Energy dependence changes in SPS region
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Christoph Blume Florence, July 3-6 2006 18 Elliptic Flow Model Comparison of v 2 for Pions H. Petersen, Hot Quarks06 Squeeze-out at lower energies not described w/o nuclear potential Energy dependence of v 2 not described by UrQMD At higher energies: lack of inital pressure! Indication for onset of partonic flow at SPS?
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Christoph Blume Florence, July 3-6 2006 19 Elliptic Flow v 2 for Protons at 40A GeV ? NA49 PRC 68 (2003) 034903 Disappearance of proton flow? Evidence for 1 st order phase transition H. Stöcker, nucl-th/0406018 Standard method different to cumulant method at mid-rapidity Larger systematic error Systematic study with higher precision needed Challenge for future experiments!
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Christoph Blume Florence, July 3-6 2006 20 Bose-Einstein Correlations Energy Dependence of Radius Parameters
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Christoph Blume Florence, July 3-6 2006 21 Bose-Einstein Correlations Energy Dependence of Radius Parameters k t 0.2GeV/c No indication for strong energy dependence between AGS and RHIC Structures? But: Unresolved discrepancies between SPS experiments!
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Christoph Blume Florence, July 3-6 2006 22 Bose-Einstein Correlations Model Comparison: UrQMD NA49 data 20A – 158A GeV Reasonable description by transport model (R 2 out -R 2 side ) 1/2 slightly larger in model M. Bleicher, GRC06 QingFeng Li, Frankfurt
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Christoph Blume Florence, July 3-6 2006 23 Bose-Einstein Correlations Model Comparison: UrQMD No structure in energy dependence in data and transport model Data M. Bleicher, GRC06 QingFeng Li, Frankfurt
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Christoph Blume Florence, July 3-6 2006 24 Summary Evidences for structures in hadronic exciation functions Around s NN = 7-8GeV Particle Yields Qualitatively close to to statistical model expectations Clear deviations seen for kaons and Maxima in X/ ratios as in stat. model ? Indication for sudden change in strangeness e.-dep. Transverse mass spectra Sudden change of m t Change of radial flow EOS ? Elliptic flow No clear evidence, higher presision data needed Bose-Einstein correlations No evidence for structure High precision data mandatory!
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Christoph Blume Florence, July 3-6 2006 25 Thanks!
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Christoph Blume Florence, July 3-6 2006 26 High p t Energy Dependence of R CP for Pions and h - ? R pA Strongest drop of R CP between s = 17.3GeV and s = 62.4GeV Any onset at low energies? SPS
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Christoph Blume Florence, July 3-6 2006 27 Particle Yields Energy Dependence of K + / + Central Pb+Pb/Au+Au Mid-rapidity ratios Same structure as for 4
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Christoph Blume Florence, July 3-6 2006 28 Particle Yields Energy Dependence of 4 Yields AGSNA49BRAHMS Central Au+Au, Pb+Pb Access to the energy dependence of identified particle yields in the range s NN = 2.5 – 200 GeV
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Christoph Blume Florence, July 3-6 2006 29 Transverse Mass Spectra Inverse Slope Parameters of Kaons Feature cannot be described by transport models Y. Hama et al. Braz. J. Phys. 34 (2004), 322, hep-ph/0309192 Hydro calculation with assumption of 1st order phase transition Change of EOS seen?
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Christoph Blume Florence, July 3-6 2006 30 Transverse Mass Spectra Inverse Slope Parameters of Kaons Step in energy dependence p+p compilation from: M. Kliemant, B. Lungwitz, and M. Gazdzicki, PRC 69 (2004) 044903 Seems to be absent in p+p
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Christoph Blume Florence, July 3-6 2006 31 Transverse Mass Spectra “Hydro” - Model Basic model: Common freeze-out of all particle types Boost invariant longitudinal expansion Transverse expansion is modelled by a velocity profile “Standard” version: Schnedermann, Sollfrank, and Heinz, Phys. Rev. C46 Extended version: Resonance contribution included Baryonic resonances introduce dependence on B Chemical freeze-out: T ch and B taken from freeze-out curve Thermal freeze-out: System cools down, therefore assume: Conservation of entropy Conservation of effective particle numbers U. Wiedemann and U. Heinz, Phys. Rev. C56 (1997) 3265 B. Tomasik, nucl-th/0304079
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Christoph Blume Florence, July 3-6 2006 32 Transverse Mass Spectra “Hydro” – Model Fits E895: nucl-ex/0306033 NA49: Phys. Rev. C66 (2002) 054902, nucl-ex/0403023 PHENIX: Phys. Rev. C69 (2004) 024904, nucl-ex/0307022 Convave Resonances ExponentialShoulder Radial flow -- K - p
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Christoph Blume Florence, July 3-6 2006 33 Transverse Mass Spectra Energy Dependence of Fit Parameter Fit to -, K - and p Box-shaped source profile and linear velocity profile Fit range 0.1 < m t -m 0 < 0.8 GeV Energy dependence of T f seems to change around 30 AGeV Thermal and chemical freeze-out different? Single freeze-out model? Continous increase of T T ch
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Christoph Blume Florence, July 3-6 2006 34 Transverse Mass Spectra Blast Wave Fits Good description of all particle species at SPS energies Blast wave implementation: F. Retiere and M. Lisa nucl-th/0312024 Fit parameters:
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Christoph Blume Florence, July 3-6 2006 35 Bose-Einstein Correlations Blast Wave Model Fits Combined fit to HBT radii and transverse mass spectra Good fit to the data slight deviations in R side at high k t Blast wave implementationn: M. Lisa, F. Retiere, nucl-th/0312024 Emission function: Fit parameters:
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Christoph Blume Florence, July 3-6 2006 36 Bose-Einstein Correlations Thermal Freeze-Out Parameters T chem J. Cleymans, K. Redlich, Phys. Rev. C60, 054908 (1999) Slightly increasing temperature with beam energy Approx. constant transverse geometrical Radii (R box 2R gauss ) Finite emission duration at SPS energies
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Christoph Blume Florence, July 3-6 2006 37 Bose-Einstein Correlations Energy Dependence of Freeze-Out Volume D. Adamová et al. (CERES collaboration), Phys. Rev. Lett. 90 (2003) 022301. Minimum in freeze-out volume in SPS region Possible explanation: Constant mean free path freeze-out condition Transition baryon meson dominated But: Unresolved inconsistencies between SPS experiments!
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Christoph Blume Florence, July 3-6 2006 38 Bose-Einstein Correlations Energy Dependence of Freeze-Out Volume k t 0.15GeV/c
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Christoph Blume Florence, July 3-6 2006 39 Particle Yields Antilambda-Antiproton Ratio Increase above 1 towards lower energies consistent with recent NA49 data Models predict ratio < 1 Hadron Gas 1: J. Manninen et al. Hadron Gas 2: K. Redlich et al. Hadron Gas 3: J. Rafelski et al.
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Christoph Blume Florence, July 3-6 2006 40 Particle Yields Antibaryon-Baryon Ratio Strong increase of B/B ratio in SPS energy range Energy dependence weakens with increasing strangeness content Lines: Statistical hadron gas model J. Manninen et al. Fit to 4 data! NA49 preliminary No indications for structures in energy dependence
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