Ultra-relativistic nuclear collisions and Production of Hot Fireballs at SPS/RHIC

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1 Ultra-relativistic nuclear collisions and Production of Hot Fireballs at SPS/RHIC Benjamin Dönigus Seminar WS 2009/2010 Relativistische Schwerionenphysik Interface of Quark-Gluon Plasma and Cold Quantum Gases

2 Outline Introduction SPS RHIC Elliptic Flow Jet Quenching J/ψsuppression Summary 2

3 Phase Diagram -Data from SPS is in the range from 200 MeV<μ b < 500 MeV -Data from RHIC close to μ b ~ 20 MeV -Data from RHIC close to μ b ~ 0 MeV Plot arxiv: v1 prepared by N. Xu[nucl-th] 3

4 Heavy Ion Collisions Time Cartoon of a Ultra-relativistic heavy-ion collision. Left to right: - the two lorentz contracted nuclei approach, - collide, - form a Quark-Gluon Plasma (QGP), - the QGP expands and hadronizes, - finally hadrons rescatter and freeze out Plot by S. Bass, Duke University; 4

5 Time evolution of the QCD matter in heavy ion collisions Movie provided by S. Vogel, ITP Frankfurt The fireball evolution: Starts with a pre-equilibrium state Forms a Quark-Gluon Plasma phase (if T is larger than T c ) At chemical freeze-out, T ch, hadrons stop being produced At kinetic freeze-out, T fo, hadrons stop scattering movie4_cinepak.avi 5

6 Lattice QCD results Lattice QCD tells us where to expect the phase transition arxiv:hep-lat/ Critical energy density: 4 ε = 7 ± 1) T C ( C T C ~ 175 MeV ε C ~ 1 GeV/fm 3 A. Bazavov et al.,phys.rev.d80:014504,2009 6

7 Temperature of the source 1000 π Light source particle source N Distribution is fitted best with Multiplicity K 0 K - K + η N φ Λ Λ Ξ Ω T = K 1/40 ev = 300 K T ch = 175 x 10 6 ev = K Ξ Ω x hotter than in the centre of the sun E = mc 2 (GeV) 7

8 Thermal fits to SPS data A. Andronic et al., Acta Phys.Polon.B 40 (2009) Experimental hadron yields and model calculations for the parameters of the best fit at SPS for the energy of 7.6 GeV with the statistical hadronization model 8

9 Thermal fits to RHIC data - Experimental hadron yields and model calculations for the parameters of the best fit for RHIC data at the energy of 200 GeV calculated with the statistical hadronization model A. Andronic et al., Acta Phys.Polon.B 40 (2009)

10 Thermal fits - The energy dependence of the temperature and baryon chemical potential at chemical freeze-out. - The lines are parametrizations for T and μ b. arxiv: v1 [nucl-th] 10

11 The CERN accelerator complex LHC Northern Area SPS Western Area CERN main site Oct. 13, 2009 K. Oyama 11

12 From C. Lourenco 12

13 NA45/CERES 13

14 Au +Au Cu + Cu d + Au p + 20, 62, 130, , 62, , 400 GeV

15 STAR as an 15

16 Au + Au Collisions at RHIC Peripheral Event 16 STAR (real-time Level 3)

17 Au + Au Collisions at RHIC Mid-Central Event 17 STAR (real-time Level 3)

18 Au + Au Collisions at RHIC Central Event 18 STAR (real-time Level 3)

19 RHIC Highlights as seen by Scientific American 19

20 Elliptic Flow p y φ = arc tan p p y x p x y x z dn dφ ε = y 2 x p x p y v y 2 + x 2 2 = 2 2 p + p Initial coordinate-space anisotropy v2 cos[2( φ ΨR )] + 2v cos[4( φ ΨR )] +... Elliptic term x Final momentum-space anisotropy Anisotropy self-quenches, so v 2 is sensitive to early times y 20

21 Gas of weakly/strongly interacting Li atoms excite Feshbach resonance M. Gehm et al, Science 298, 2179 strongly coupled weakly coupled 21

22 Elliptic Flow An increase of the elliptic flow v 2 for higher center of mass energies of the collided systems has been measured C. Alt et al., Phys. Rev. C68, (2003) 22

23 v 2 for different particle species A Taranenko et al., J. Phys. G: Nucl. Part. Phys. 34 (2007) S1069 -v 2 for different particle species - hard to extract usefull information from this plot 23

24 Collectivity, Deconfinement at RHIC - v 2 of light hadrons and multi-strange hadrons - scaled with the number of constituent quarks - Partonic collectivity Deconfinement A. Adare et al., Phys.Rev.Lett.98:162301,

25 Observation of Jet Quenching hadrons leading particle suppressed q? q C. Adler et al., Phys. Rev. Lett. 91 (2003) After the initial hard-scattering, the parton interacts strongly with the dense medium in central Au+Au collisions at RHIC 25

26 J/ψ Suppression J/ψ : bound state of one charm and one anticharm quark Hydrogen-like radius: 0.45 fm mass: GeV >> T charm- and anticharm-quarks are created in initial hard collisions by gluon fusion Inside the QGP: attractive interaction between charm and anticharm quark is screened through gluons and other quark types (color screening) consequence: expectation of suppressed J/ψ yields when QGP is created (predicted by T. Matsui and H. Satz, Phys. Lett. B 178 (1986) 416) 26

27 J/ψ suppression - Nuclear modification factor is the ratio between nucleusnucleus and scaled nucleonnucleon collisions - Comparison of the nuclear modification factor between SPS and RHIC measurements - Screening would expect stronger suppression at RHIC than at SPS centrality E. T. Atomssa, Eur. Phys. J. C 61 (2009)

28 J/ψ suppression centrality A. Andronic et al., Phys.Lett.B652: , Suppression is seen at RHIC too - Statistical model calculation give reasonable agreement with RHIC data - Statistical model even expects enhancement at LHC energies - Statistical model assumes creation of the ccbar in the inital collision and full screening of the J/ψ 28

29 Summary Evolution of the fireball Thermal model describes particle production SPS ( ): J/ψ suppression deconfinement compelling evidence for a new state of matter with QGP-like properties RHIC (2000-?): parton energy loss (jet quenching) parton flow compelling evidence for a strongly-coupled QGP ( the perfect fluid ) 29

30 Thanks for your attention! 30