P.Seyboth: Indications for the onset of deconfinement in Pb+Pb collisions at the CERN SPS from NA49 (ISMD2004) 1 Indications for the Onset of Deconfinement in Pb+Pb Collisions at the CERN SPS from NA49 Introduction Search for structure in the energy dependence of –Inclusive particle production –E-by-E fluctuations, BE correlations, flow Summary and conclusion P.Seyboth, MPI für Physik, Munich for the NA49 collaboration

P.Seyboth: Indications for the onset of deconfinement in Pb+Pb collisions at the CERN SPS from NA49 (ISMD2004) 2 Introduction: Pb+Pb collisions at top SPS energy Initial energy density exceeds the critical value predicted by lattice QCD ( 1 GeV / fm 3 ) Strong collective behavior –anisotropic and radial flow –transverse expansion of the matter droplet by factor 2 Proposed signatures for deconfinement observed –Strangeness enhancement –Low-mass dilepton enhancement –J/Ψ,Ψ’ yield suppression Signatures not unique Search for a threshold by varying the energy for the largest collision system (central Pb+Pb reactions)

P.Seyboth: Indications for the onset of deconfinement in Pb+Pb collisions at the CERN SPS from NA49 (ISMD2004) 3 The NA49 Detector Target: 20cm liquid H 2 or Pb foil VCAL detects projectile spectators Δp/p 2 = 7 (0.3) (GeV/c) -1 (VTPC-1, VTPC+MTPC) dE/dx resolution 3 – 6 % TOF resolution ~ 60 ps p > 7 GeV dE/dx forward rapidity 2,5 < p < 10 GeV : TOF + dE/dx at midrapidity

P.Seyboth: Indications for the onset of deconfinement in Pb+Pb collisions at the CERN SPS from NA49 (ISMD2004) 4 Pb+Pb collision at 158A GeV

P.Seyboth: Indications for the onset of deconfinement in Pb+Pb collisions at the CERN SPS from NA49 (ISMD2004) 5 NA49 energy scan program of central Pb+Pb collisions search for structure in the energy dependence of observables which may be linked to the onset of deconfinement Beam Energy Centrality Event Statistics Taken in 158A GeV10 %800 k A GeV20 %3,000 k A GeV7 %300 k A GeV7 %700 k A GeV7 %400 k A GeV7 %300 k2002 preliminary PRC 66(2003)

P.Seyboth: Indications for the onset of deconfinement in Pb+Pb collisions at the CERN SPS from NA49 (ISMD2004) 6 Rapidity spectra (open dots from reflection at y cm = 0) Extrapolation  4π yields also: Ξ, Ω

P.Seyboth: Indications for the onset of deconfinement in Pb+Pb collisions at the CERN SPS from NA49 (ISMD2004) 7 Transverse mass spectra at mid-rapidity 158A GeV many spectra measured well described by fireball model assuming common temperature and flow “blast wave”: (Schnedermann,Sollfrank, Heinz : PRC 48 (1993) 2462)

P.Seyboth: Indications for the onset of deconfinement in Pb+Pb collisions at the CERN SPS from NA49 (ISMD2004) 8 Transverse mass spectra at lower energy: 40A GeV 30A GeV 20A GeV “kinetic” freeze out at T  120 –130 MeV, β T  0.4 – 0.5 at SPS “blast wave” model describes spectra at all SPS energies

P.Seyboth: Indications for the onset of deconfinement in Pb+Pb collisions at the CERN SPS from NA49 (ISMD2004) 9 Particle yields – statistical model hadron species populated according to phase space probabilities (max.entropy) (Fermi,Hagedorn) strangeness sector not fully saturated (Rafelski) statistical model successful, T, μ B, γ S, V larger value of γ S in A+A due to relaxation of local strangeness conservation (fits by F.Becattini et al, PRC69(2004)024905)

P.Seyboth: Indications for the onset of deconfinement in Pb+Pb collisions at the CERN SPS from NA49 (ISMD2004) 10 Particle yields at 40A, 80A GeV – statistical model at lower energies μ B increases, while T decreases slightly

P.Seyboth: Indications for the onset of deconfinement in Pb+Pb collisions at the CERN SPS from NA49 (ISMD2004) 11 Global view - Phase diagram statistical model describes yields from SIS to RHIC energy T of “hadrochemical” freeze out increases SIS  RHIC μ B decreases (increase of pion production) freeze out at E  1 GeV per particle  dashed line (Lattice-QCD phase boundary: Fodor,Katz JHEP04(2004)050) hadrochemical freeze out parameters approach the phase boundary at SPS (Cleymans and Redlich, PRL 81(1998) 5284 ) QGP Hadrons 1st order

P.Seyboth: Indications for the onset of deconfinement in Pb+Pb collisions at the CERN SPS from NA49 (ISMD2004) 12 Energy dependence - π yields increase of / with energy gets steeper in SPS range π deficit changes to enhancement compared to p+p pions are most abundant particle species  measure of entropy in statistical models SMES: statistical model of the early stage Increase of initial d.o.f. g between AGS and SPS ? (Gazdzicki,Gorenstein : Acta Phys.Pol. B30(1999)2705)

P.Seyboth: Indications for the onset of deconfinement in Pb+Pb collisions at the CERN SPS from NA49 (ISMD2004) 13 Energy dependence - ratio of K,Λ yields to pions sharp peak of K + /π + ratio smooth rise of anti-Λ/π ( s quarks) similar peak in Λ/π ratio structure in K – /π – ( s quarks) hadronic models do not (yet ?) reproduce the sharp peak

P.Seyboth: Indications for the onset of deconfinement in Pb+Pb collisions at the CERN SPS from NA49 (ISMD2004) 14 Energy dependence – ratio of strange hadrons to pions hadronic mixed partonic strangeness to pion ratio peaks sharply at the SPS SMES explanation: - entropy, number of s,sbar quarks conserved from QGP to freezeout - ratio of strange/nonstrange d.o.f. rises rapidly with T in hadron gas - E s drops to predicted constant level above the deconfinement threshold onset of deconfinement at SPS ? hadronic mixed partonic

P.Seyboth: Indications for the onset of deconfinement in Pb+Pb collisions at the CERN SPS from NA49 (ISMD2004) 15 Energy dependence – inverse slope parameters inverse slope parameter T of K + and K - constant at SPS approximately constant pressure and temperature in mixed phase ? (L.van Hove, PLB89(1982)253 M.Gorenstein et al.,PLB567(2003)175)

P.Seyboth: Indications for the onset of deconfinement in Pb+Pb collisions at the CERN SPS from NA49 (ISMD2004) 16 Energy dependence - average transverse mass Increase of for abundantly produced particles ( π, K, p) slows sharply at the lowest SPS energy

P.Seyboth: Indications for the onset of deconfinement in Pb+Pb collisions at the CERN SPS from NA49 (ISMD2004) 17 The Event-by-Event K/π ratio Increased fluctuation signal at lower beam energies Beam Energy σ 2 dyn = σ 2 data – σ 2 mixed NA49 preliminary max.likelihood fit for each event

P.Seyboth: Indications for the onset of deconfinement in Pb+Pb collisions at the CERN SPS from NA49 (ISMD2004) 18 The Event-by-Event p/π ratio Beam Energy NA49 preliminary The distribution of the E-by-E p/π ratio is narrower for data than mixed events. Effect of baryon resonance decay ?

P.Seyboth: Indications for the onset of deconfinement in Pb+Pb collisions at the CERN SPS from NA49 (ISMD2004) 19 Electric charge fluctuations Smaller in a QGP than in a hadron gas (Jeon,Koch,Asakawa,Heinz,Müller) Effect of hadronisation ? Central Pb+Pb collisions 158A GeV Global charge conservation

P.Seyboth: Indications for the onset of deconfinement in Pb+Pb collisions at the CERN SPS from NA49 (ISMD2004) 20 QGP signature possibly masked by effect of resonance decays No clear energy dependence of charge fluctuations at SPS Remove effect of global charge conservation :

P.Seyboth: Indications for the onset of deconfinement in Pb+Pb collisions at the CERN SPS from NA49 (ISMD2004) 21 BE correlations: energy dependence of radius parameters k T ~ 0.15 GeV/c R long increases slowly R side constant R out constant no evidence of anomalies or “soft point” of EOS

P.Seyboth: Indications for the onset of deconfinement in Pb+Pb collisions at the CERN SPS from NA49 (ISMD2004) 22 Anisotropic flow v 2 Initial anisotropy ε in non-central collisions transformed into momentum anisotropy v 2 by pressure at early reaction stage Smooth increase with collision energy towards hydrodynamic model prediction ε = ( + )/( - ) SPS RHIC

P.Seyboth: Indications for the onset of deconfinement in Pb+Pb collisions at the CERN SPS from NA49 (ISMD2004) 23 Conclusion from the energy scan at the SPS structure observed at low SPS energy in central Pb+Pb collisions – the rate of increase of pion production steepens – the strange particle to pion ratio peaks sharply – constancy of the slope of π and K m T - spectra no evident anomalies in e-by-e fluctuations (K/π, charge), BE correlations and flow present models without deconfinement in the early phase do not reproduce details of energy dependence reaction scenario with onset of deconfinement at the SPS can explain the observed structure  plan to continue SPS program with lighter nuclei: role of the initial volume in the onset of deconfinement search for the predicted critical point

P.Seyboth: Indications for the onset of deconfinement in Pb+Pb collisions at the CERN SPS from NA49 (ISMD2004) 24 The NA49 collaboration

P.Seyboth: Indications for the onset of deconfinement in Pb+Pb collisions at the CERN SPS from NA49 (ISMD2004) 25 Extra slides for discussion

P.Seyboth: Indications for the onset of deconfinement in Pb+Pb collisions at the CERN SPS from NA49 (ISMD2004) 26 Estimate of initial energy density at 158A GeV from projectile energy loss and interaction volume: from transverse energy production and Bjorken’s model: initial energy density ε > ε c  1 GeV/fm 3 NA49, PRL 75 (1995) 3814

P.Seyboth: Indications for the onset of deconfinement in Pb+Pb collisions at the CERN SPS from NA49 (ISMD2004) 27 Λ, Ξ and Ω rapidity spectra

P.Seyboth: Indications for the onset of deconfinement in Pb+Pb collisions at the CERN SPS from NA49 (ISMD2004) 28 Transverse mass spectra in p+p collisons at 158 GeV consistent with common temperature T  145 MeV “blast wave” model fit consistent with small β T

P.Seyboth: Indications for the onset of deconfinement in Pb+Pb collisions at the CERN SPS from NA49 (ISMD2004) 29 Statistical model for p+p collisions at 158 GeV

P.Seyboth: Indications for the onset of deconfinement in Pb+Pb collisions at the CERN SPS from NA49 (ISMD2004) 30 Energy dependence of K, Λ yields  carriers of s quarks

P.Seyboth: Indications for the onset of deconfinement in Pb+Pb collisions at the CERN SPS from NA49 (ISMD2004) 31 Energy dependence of total yield of s, s carriers  carriers of s quarks

P.Seyboth: Indications for the onset of deconfinement in Pb+Pb collisions at the CERN SPS from NA49 (ISMD2004) 32

P.Seyboth: Indications for the onset of deconfinement in Pb+Pb collisions at the CERN SPS from NA49 (ISMD2004) 33 System size dependence of strangeness production at 158A GeV disappearance of canonical suppression for N part > 60

P.Seyboth: Indications for the onset of deconfinement in Pb+Pb collisions at the CERN SPS from NA49 (ISMD2004) 34

P.Seyboth: Indications for the onset of deconfinement in Pb+Pb collisions at the CERN SPS from NA49 (ISMD2004) 35

P.Seyboth: Indications for the onset of deconfinement in Pb+Pb collisions at the CERN SPS from NA49 (ISMD2004) 36 Balance function for oppositely charged particles 158A GeV (NA49 preliminary) similar narrowing at SPS and RHIC

P.Seyboth: Indications for the onset of deconfinement in Pb+Pb collisions at the CERN SPS from NA49 (ISMD2004) 37 Event-by-Event estimation of the particle ratios Vary relative normalization of the particle species (K/ ,p/  ) in the probability density function Extract ratios with maximum likelihood fit One Event: Probability density function: Fit dE/dx spectra in 4D binning Event Ensemble: log(Ptot [GeV])

P.Seyboth: Indications for the onset of deconfinement in Pb+Pb collisions at the CERN SPS from NA49 (ISMD2004) 38 v 2 (p T ) at SPS and RHIC

P.Seyboth: Indications for the onset of deconfinement in Pb+Pb collisions at the CERN SPS from NA49 (ISMD2004) 39 Fluctuations of vs system size at 158A GeV selected range: 4.0 < y π < 5.5 corrected for limited 2-track resolution

P.Seyboth: Indications for the onset of deconfinement in Pb+Pb collisions at the CERN SPS from NA49 (ISMD2004) 40 Fluctuations of vs system size at 158A GeV (NA49 preliminary) correction for fluct. in projectile participants: selected range: 4 < y < 5.5

P.Seyboth: Indications for the onset of deconfinement in Pb+Pb collisions at the CERN SPS from NA49 (ISMD2004) 41 Multiplicity fluctuations at 158A GeV (NA49 preliminary)