Bulk  Eigenschaften von QCD  Materie bei höchsten Kolliderenergien Kai Schweda, Universität Heidelberg / GSI Darmstadt

Building Blocks of Matter Quantum Chromodynamics (QCD) is the established theory of strongly interacting matter. Gluons hold quarks together to from hadrons: Gluons and quarks, or partons, typically exist in a color singlet state: confinement. meson baryon

Quark Gluon Plasma Quark Gluon Plasma: Deconfined and Source: Michael Turner, National Geographic (1996) Quark Gluon Plasma: Deconfined and thermalized state of quarks and gluons  Study partonic Equation of State: relation between p, , T

Colliding Heavy Nuclei

Outline Identify and study QCD bulk-matter with partonic degrees of freedom: Collectivity at RHIC ALICE at LHC at the energy frontier CBM at FAIR at the baryon density frontier Summary

High-Energy Nuclear Collisions Time  1) Initial condition: 2) System evolves: 3) Bulk freeze-out Baryon transfer - parton/hadron expansion - hadronic dof - ET production - inel. interactions cease: Partonic dof particle ratios, Tch, mB - elas. interactions cease Particle spectra, Tth, <bT> The only possibility to create such a state is by colliding heavy nuclei at the highest energies. You see here a schematic view of a nuclear collisions. Both nuclei are lorentz contracted along the beam direction. They overlap and deposit energy in the collision region. The systems then evolves, it expands and therefore cools down. Hadrons are formed. The system gets more and more dilute. When inelastic interaction cease, hadron yields are fixed, this is commonly referred as chemical freeze out. Finally, elastic interaction cease and particle spectra are fixed, kinetic freeze-out. Plot: Steffen A. Bass, Duke University

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

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

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

Hadron Yield - Ratios 1) At RHIC: Tch = 160 ± 10 MeV B = 25 ± 5 MeV  The hadronic system is thermalized at RHIC. 3) Short-lived resonances show deviations.  There is life after chemical freeze-out. RHIC white papers - 2005, Nucl. Phys. A757, STAR: p102; PHENIX: p184; Statistical Model calculations: P. Braun-Munzinger et al. nucl-th/0304013.

Chemical Freeze-Out vs Energy With increasing energy: Tch increases and saturates at Tch = 160 MeV Coincides with Hagedorn temperature Coincides with early lattice results  limiting temperature for hadrons, Tch  160 MeV ! mB decreases, mB  1MeV at LHC  Nearly net-baryon free ! A. Andronic et al., NPA 772 (2006) 167.

QCD Phase Diagram

Pressure, Flow, … Thermodynamic identity – entropy p – pressure U – energy V – volume t = kBT, thermal energy per dof In A+A collisions, interactions among constituents and density distribution lead to: pressure gradient  collective flow number of degrees of freedom (dof) Equation of State (EOS) cumulative – partonic + hadronic

(Anti-)Protons From RHIC More central collisions In central collisions, spectra become more convex  stronger collective flow !

Kinetic Freeze-out at RHIC 1) Multi-strange hadrons  and  freeze-out earlier than (p, K, p)  Collectivity prior to hadronization 2) Sudden single freeze-out*: Resonance decays lower Tfo for (p, K, p)  Partonic Collectivity STAR Preliminary STAR Data: Nucl. Phys. A757, (2005 102), *A. Baran, W. Broniowski and W. Florkowski, Acta. Phys. Polon. B 35 (2004) 779.

Anisotropy Parameter v2 coordinate-space-anisotropy  momentum-space-anisotropy y py x px Initial/final conditions, EoS, degrees of freedom

v2 in the Low-pT Region P. Huovinen, private communication, 2004 Minimum bias data! At low pT, model result fits mass hierarchy well! - Details do not work, need more flow in the model!

v2 of Multi-Strange Hadrons  and  Strange-quark flow - partonic collectivity at RHIC! NB:  K+ + K- (BR 49%)  e+ + e- (BR 0.03%) QM05 conference: M. Oldenburg; nucl-ex/0510026.

Collectivity - Energy Dependence Collectivity parameters <bT> and <v2> increase with energy Two extreme scenarios: (a) Tfo  Tch AND br  0.8  pure partonic collectivity at LHC! (b) Tfo  Tch , br  0.3  no collectivity, no QGP ! K.S., ISMD07, arXiv:0801.1436ﾊ[nucl-ex].

Partonic Collectivity at RHIC 1) Copiously produced hadrons freeze-out p,K,p: Tfo = 100 MeV, T = 0.6 (c) > T(SPS) 2) Multi-strange hadrons freeze-out : Tfo = 160-170 MeV (~ Tch), T = 0.4 (c) 3) Multi-strange v2: Multi-strange hadrons f,  and  do flow! 4) Constituent Quark scaling: Seems to work for v2 and RAA (RCP) Deconfinement & Partonic (u,d,s) Collectivity !

Particle Multiplicities PHOBOS fit HIJING BBar Armesto et al. AMPT Eskola CGC KLN ASW DPMJET-III EHNRR at LHC, dN/dh  1000 - 3000 estimate energy density PHOBOS compilation: W. Busza, SQM07. Theory points: HI at LHC – last call for predictions, CERN, May 2007.

EoS from Lattice QCD 1) Large increase in  ! Large increase in Ndof: Hadrons vs. partons 2) TC ~ 160 MeV 3) Boxes indicate max. initial temperatures Longest expansion duration at LHC Expect large partonic collectivity at LHC SPS RHIC LHC ? Z. Fodor et al, JHEP 0203:014(02) C.R. Allton et al, hep-lat/0204010 F. Karsch, Nucl. Phys. A698, 199c(02).

Heavy  Quark Production Heavy-quark production at LHC, compared to RHIC expect factors Charm  10 Beauty  100 (i) Heavy-quarks abundantly produced at LHC energies ! (ii) Large theoretical uncertainties  energy scan (LHC,FAIR) will help ! Plots: R. Vogt,Eur. Phys. J. C, s10052-008-0809-x (2008).

Quark Masses Strong interactions do not affect heavy-quark masses. Higgs mass: electro-weak symmetry breaking (current quark mass). QCD mass: Chiral symmetry breaking (constituent quark mass). Strong interactions do not affect heavy-quark masses. New scale: mc >> QCD. Calibrated probe: - test pQCD, initial cond. - drag/diffusion - chiral symmetry rest. X. Zhu, M. Bleicher, K.S., H. Stoecker, N. Xu et al., PLB 647 (2007) 366.

Debye Screening

J/y Production  suppression, compared to scaled p+p P. Braun-Munzinger and J. Stachel, Nature 448 (2007) 302.  suppression, compared to scaled p+p  regeneration, enhancement (SPS) Low energy (SPS): few ccbar quarks in the system  suppression of J/y High energy (LHC): many ccbar pairs in the system  enhancement of J/y  Signal of de-confinement + thermalization of light quarks !

Predictions for LHC scc large charm production at LHC strong regeneration of J/y striking centrality dependence Signature for QGP formation ! Initial conditions at LHC ? Need to measure total charm production in PbPb ! Also: check ’ ratio vs stat. model predictions scc A. Andronic et al., Phys. Lett. B 652 (2007) 259.

D  Dbar Correlations vs  PYTHIA: p + p @ 14 TeV c-cbar Mesons are correlated Pair creation: back to back Gluon splitting: forward Flavor excitation: flat Exhibit strong correlations ! Baseline at zero: clear measure of correlations !  probe thermalization among partons ! G. Tsiledakis and K.S., 0903.0366[nucl-ex], 0901.4296[nucl-ex].

Where does all the charm go? J c D*± Ds D0 D Measure open-charm mesons, e.g. D0 and D* to address: (a) total charm production (b) heavy-quark collectivity Statistics plot: H. Yang and Y. Wang.

Hadronen mit schweren Quarks (charm und beauty) Viele neue interessante Signale in ALICE bei LHC: z.B. Hadronen mit schweren Quarks (charm und beauty) D0, D+, D*, Ds, J/y, y’, Lc, Lb, 

Large Hadron Collider LHC at CERN p + p @ 7 + 7 TeV Pb + Pb @ 2.76 + 2.76 TeV LHC 7 TeV c - 10 km/h Tevatron 0.98 TeV c - 495 km/h RHIC 250 GeV c - 7602 km/h Geiger and Marsden 1 MeV c * 5%

ALICE at LHC 1000 scientists, 30 nations TRD ITS TPC ITS: measures secondary vertex, open heavy-flavor, c and b TPC: tracks and identifies charged particles, (e,), , K, p TRD: identifies electrons above 1 GeV, fast trigger (6s)

D0  p+ + K- Reconstruction D0, ct = 123 mm Plot: A. Shabetai

D0 - Meson Performance Measure secondary vertex  Direct reconstruction of D0  precise measurement of total heavy-quark yield  address heavy – quark collectivity ! ALICE: PPR.vol.II, J. Phys. G 32 (2006) 1295.

D* meson Identification D*+  D0 + + Identify D*+ through M[D*+ - D0] Subtract resonance decay to D0 Two different methods to address total charm production D*± analysis: Yifei Wang, Ph.D. thesis, University of Heidelberg, in preparation.

J/y  e+ + e- Reconstruction J/y: c c : b b J/y  e+ + e- identify electrons through their transition radiation  Precise Measurement of Quarkonia ! Wolfgang Sommer, Ph.D. thesis, Frankfurt University.

ALICE in 2004

ALICE: Getting ready…

ALICE - Ready for Physics !

Summary LHC Bulk properties at LHC: dN / dh  1000 – 3000 Tch  160 ± 10 MeV, mB  0 – 5 MeV Tfo  Tch  all collectivity from partonic stage <bT> = 0.8 ± 0.05 (c), <v2>  0.08 Measure spectra, correlations and v2 of: D0, D+, D*, Ds, J/y, y’, Lc, Lb,  to identify and characterize QGP ! ALICE is well suited for these studies

Energy Dependence Look for statistical hadronization of charm at top FAIR energies c most sensitive ! Need total charm cross section as reference: measure D-mesons !  Need -vertex detector

Chiral Partners ? cu-system D-mesons: heavy-light system hydrogen atom of QCD (0+) (1+) Belle (2003) ~Mq D(2308) D(2427) Chiral mass shifts  420 MeV (constituent quark mass) D(0+)  D(0-) +  c u 1- 0- D*(2010) ~1/mQ Light-quark-cloud probes chiral symmetry D(1869) Look for effects of chiral symmetry restoration at CBM/FAIR using heavy-quarks !

Kurtosis Analysis for Net  Baryons Quark Number Susceptibility On Lattice: a spike in susceptibility means long range correlation at the critical point. The equilibration of the medium is assumed in all Lattice calculations. In Experiment: measure the correlation function of net-baryons or p, . Need -vertex detector ! Light quarks Strange quarks

Nuclear phase diagram Heavy quarks with ALICE at LHC: - Study medium properties - pQCD in hot and dense environment FAIR/GSI program: - Search for the possible phase boundary. - Chiral symmetry restoration Energy scan