Recent Results from NA49

Christoph Blume XXXXth Rencontres de Moriond QCD and High Energy Hadronic Interactions March 12-19, 2005

Heavy Ion Physics at the CERN SPS

Exploring 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 – E beam (  s NN = 20 - 158 A GeV = 6.3 - 17.3 GeV)  Use hadronic observables to pin down phase transition Cross over  Systematic studies required:  Energy dependence Critical point 1st order Lattice calculations: Fodor and Katz Bielefeld-Swansea group Christoph Blume XXXXth Rencontres de Moriond, March 12-19 2005 2

Heavy Ion Physics at the CERN SPS

The NA49 Experiment

13m

Particle identification: Pions, charged Kaons: K 0 s ,  ,  ,  :  : dEdx in TPCs + TOF (mid-rapidity) Decay topology + invariant mass Invariant mass of identified Kaons Christoph Blume XXXXth Rencontres de Moriond, March 12-19 2005 3

Outline

    Energy dependence – Rapidity spectra – Transverse mass spectra – 4  particle yields Event-by-event fluctuations – Energy dependence of K/  fluctuations – System size dependence of multiplicity fluctuations Elliptic flow of Lambdas Outlook: “High” p t at the SPS – Identified particle spectra at high p t Christoph Blume XXXXth Rencontres de Moriond, March 12-19 2005 4

Rapidity Spectra

Central Pb+Pb 7% (20-80) 5/10% (158) Change of shape only for  Others: ~ Gaussians Christoph Blume XXXXth Rencontres de Moriond, March 12-19 2005 5

Rapidity Spectra

Energy Dependence of Widths Linear dependence on y beam (works up to RHIC !) Clear hierarchy for Gaussian-like particles at SPS (p,  ,  excluded):  > K + > K ,  >  Seems to break down at AGS  Thermal component of longitudinal flow Christoph Blume XXXXth Rencontres de Moriond, March 12-19 2005 6

Transverse Mass Spectra

Energy Dependence of  m t  -m 0  negatively charged Energy dependence of transverse activity seems to change around 30 A GeV. General feature for pion, kaons and protons Cannot easily be reproduced by hadronic models (UrQMD, HSD)  Change of EOS ?

Christoph Blume XXXXth Rencontres de Moriond, March 12-19 2005 7

Particle Yields

Energy Dependence + Statistical Model Statistical hadron gas model:  s = 1 P. Braun-Munzinger, J. Cleymans, H. Oeschler, and K. Redlich Nucl. Phys. A697 (2002) 902  K +  /  +   K  /    /    /    1 .

5        Christoph Blume  /  XXXXth Rencontres de Moriond, March 12-19 2005  +  +  /  8

Particle Yields

Energy Dependence + Transport Models UrQMD HSD  K +  /  +  E.L. Bratkovskaya et al., PRC 69 (2004), 054907  K  /    /    /    1 .

5        Christoph Blume  /  XXXXth Rencontres de Moriond, March 12-19 2005  +  +  /  9

Fluctuations

Particle Ratios Event-by-event fluctuations of e.g. K/    Compare to mixed event reference Resolution Finite number statistics  Extraction of dynamical fluctuations s s 2 = RMS/Mean * 100 [%] dynamic = s 2 data s 2 mix Christoph Blume 160 GeV preliminary NA49 XXXXth Rencontres de Moriond, March 12-19 2005 20 GeV preliminary NA49 10

Fluctuations

Energy Dependence of K/  Fluctuations Data wider than mixed events reference Clear energy dependence of K/  fluctuations observed  Decrease with energy Fluctuation from UrQMD independent of energy Non-zero value due to energy and strangeness conservation Promising, but no clear evidence for critical point yet preliminary Christoph Blume XXXXth Rencontres de Moriond, March 12-19 2005 11

Fluctuations

System Size Dependence of Multiplicity Fl.

Normalized variance:

V V n n

     1

n



n

2  

n



n

 2 for Poisson Correction for finite width of interval D E PS and resolution of calorimeter

s NN

 17 .

2

GeV

forward rapidities 4.0 < y  < 5.5

Christoph Blume Strong centrality dependence with maximum around N w (  2 N p Proj ) = 70 Effect not seen in HIJING model XXXXth Rencontres de Moriond, March 12-19 2005 12

Elliptic Flow

Energy Dependence of Lambda v 2 ( p t ) Initial spatial anisotropy  different pressure gradients  momentum anisotropy v 2 Christoph Blume preliminary Lambda v 2 seems to be significantly lower at SPS than at RHIC XXXXth Rencontres de Moriond, March 12-19 2005 13

Elliptic Flow

Particle Type Dependence v 2 for Lambdas seems to be lower than for protons (caveat: different centrality selection) No quark number scaling (recombination) observed?

preliminary Christoph Blume XXXXth Rencontres de Moriond, March 12-19 2005 14

Outlook

“High” p t at the SPS    Very little information about “high” p t (> 2 GeV) in heavy ion reactions at SPS energies so far Jet-quenching observable?

Parton coalescence?

Cronin effect Identified particle spectra for   , K  , K 0 s , p, p,   p/  ,  /K 0 s -ratios and R cp up to (but no R p AA t = 4GeV !) Andras Laszlo Christoph Blume very perliminary central peripheral very perliminary  , K , p XXXXth Rencontres de Moriond, March 12-19 2005 charged particles 2.91 <  < 3.51

Pb+Pb 158 A GeV identified particles 2.91 <  < 3.51

Pb+Pb 158 A GeV 15

Summary

    Systematic study of  s dependence of hadronic observables:     Mass dependence of rapidity widths Change of the energy dependence of m t -spectra at 30 A GeV Evidence for phase transition ?

Maximum in the strangeness to pion ratio at 30 A GeV  Evidence for deconfinement ?

Fluctuations    No direct understanding yet, but encouraging (critial point !) Measurement of Lambda flow  Significant increase of K/  fluctuations towards lower energies Strong centrality dependence of multiplicity fluctuations Quark number scaling not observed ?

 Outlook Consistent with hydro ?

 p t -spectra of identified particles at high p t Christoph Blume XXXXth Rencontres de Moriond, March 12-19 2005 16

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 Christoph Blume XXXXth Rencontres de Moriond, March 12-19 2005 17

The End

Christoph Blume XXXXth Rencontres de Moriond, March 12-19 2005 18

Heavy Ion Physics at the CERN SPS

Particle Identification in NA49  dE/dx measured in TPCs – Large acceptance – Resolution 3-4%  Time-of-flight – Mid-rapidity – Resolution 60 ps Christoph Blume Example: Pb+Pb @ 40 AGeV XXXXth Rencontres de Moriond, March 12-19 2005 19

Rapidity Spectra

Energy Dependence of Widths Pion widths are close to Landau prediction, but not perfectly But: Perfect agreement to linear dependence on y beam Christoph Blume XXXXth Rencontres de Moriond, March 12-19 2005 20

Rapidity Spectra

Mass Dependence of Widths  negatives Approx. linear dependence on particle mass Similar slope at all SPS energies  Thermal component of longitudinal flow Christoph Blume XXXXth Rencontres de Moriond, March 12-19 2005 21

Transverse Mass Spectra

Inverse Slope Parameters of Kaons Step in energy dependence Seems to be absent in p+p How about other particle types?

Christoph Blume p+p compilation from: M. Kliemant, B. Lungwitz, and M. Gazdzicki, PRC 69 (2004) 044903 XXXXth Rencontres de Moriond, March 12-19 2005 22

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) Energy dependence of strangeness production changes at Christoph Blume  30 A GeV (1)  K 0    K +  ,  K 0    K  by isospin symmetry (2) Taken from hadron gas fit by F. Becattini et al., if not measured.

(3) Empirical factor (    assumed.

+  ) /  = 1.6

XXXXth Rencontres de Moriond, March 12-19 2005 23

Particle Yields

(Anti-)Strangeness to Pion Ratio Maximum in strangeness/pion ratio Same for s and s quarks Difficult to model Solid line: Statistical hadron gas model with  s K. Redlich, priv. comm.

= 1 Predicted as signal for the onset of deconfinement M. Gazdzicki and M.I. Gorenstein, Acta Phys. Polon. B30 (1999), 2705 Christoph Blume XXXXth Rencontres de Moriond, March 12-19 2005 24

Fluctuations

The Critical Point Endpoint of the first order phase transition line  crossover on left side Position quite uncertain But recent lattice calculations by Fodor and Katz predicts position at  B = 360 MeV using physical quark masses It might be accessible in the SPS energy range Observables: Event-by-event fluctuations Christoph Blume XXXXth Rencontres de Moriond, March 12-19 2005 25

Fluctuations

Energy Dependence of p/  Fluctuations  Data narrower than reference Can be caused by resonances Clear energy dependence of p/  fluctuations observed  Increase with energy preliminary  Similar trend seen in UrQMD Resonance contribution changes with beam energy Christoph Blume XXXXth Rencontres de Moriond, March 12-19 2005 26

Elliptic Flow

Lambda Flow Event plane from pions Flattening of accepttance via event plane shifting Corrected for event plane resolution S/B = 5-11 Christoph Blume XXXXth Rencontres de Moriond, March 12-19 2005 27