Heavy Ion Program in ALICE

1. Heavy Ion Program in ALICE A. Mastroserio Bari University & INFN On behalf of the ALICE collaboration Outline ALICE @ LHC Multiplicity, particle ratios high pt probes Summary and ALICE start up configuration A. Mastroserio - XLIIIth Rencontres de Moriond

2. LHC ~8.5 km ALICE SPS CERN ALICE @ LHC A. Mastroserio - XLIIIth Rencontres de Moriond

3. ALICE Setup ALICE Setup ITS HMPID TRD TPC MUON ARM TOF PHOS A. Mastroserio - XLIIIth Rencontres de Moriond

4. Physics topics of ALICE • Event characterization Multiplicity, centrality • Bulk properties of the hot and dense medium (dynamics of hadronization) hadron ratios, hadronic resonances • Chiral symmetry restoration Short lived resonance masses • Space-time fireball description and fireball expansion dynamics Momentum correlations (HBT), Radial and anisotropic flow • Heavy quark production Charmonium and bottonium (Debye screening, recombination(?)) • Partonic energy loss in QGP Jet reconstruction,Jet quenching, high pt spectra, inclusive high pTsuppression, open charm (Mass/color dependence of E loss) • Fluctuation phenomena Event-by-Event analysis • ……….. A. Mastroserio - XLIIIth Rencontres de Moriond

5. Multiplicity and hadronic yields A. Mastroserio - XLIIIth Rencontres de Moriond

6. ε(RHIC)~ 15 GeV/fm3 dNch/dy ~ 1200-2900 ε(LHC)~ 3 - 5 x RHIC HI Day 1 measurement dNch/dy = 2900 Eskola hep-ph/050649 dNch/dy = 1200 ln(√s) extrapolation ALICE performances tested up to dNch/dη = 8000! A. Mastroserio - XLIIIth Rencontres de Moriond

7. ALICE performances ALICE PPR Vol II J. Phys. G: Nucl. Part. Phys. 32 (2006) 1295–2040 dNch/dy = 6000 Efficiency (%) pt/pt pt/pt pt/pt ~ 3 % at 100 GeV/c Photon tagging also feasible: direct , π0, η (PHOS) A. Mastroserio - XLIIIth Rencontres de Moriond

8. A.Andronic, P.Braun-Munzinger, J. Stachel: arXiv:0707.4076v1 [nucl-th] Hadronic ratios Statistical models assume a chemical freeze out stage: hadron abundances are fixed. Chemical equilibrium model: depends on two parameters (T, μB) and it is able to describe succesfully hadron yields from SPS to RHIC energies. It predicts a chemical freeze out at LHC energies: rate of strange (especially multi-strange) hadrons is expected to strongly increase with respect to the equilibrium yields A.Andronic, P. Braun-Munzinger, J. Stachel. Nucl. Phys. A 772: 167-199, 2006 Non-equilibrium scenario:the strangeness phase space is oversaturated (S>1 in the partition function). Tch temperature depends on S and it is lower than the chemical equilibrium prediction. arXiv:0707.4076v1 [nucl-th]. 3 < S < 5 ---> 13 5 < Tch (Mev) < 125 EPJ C49 (2007) A. Mastroserio - XLIIIth Rencontres de Moriond

9. resolution ~ 1.2 MeV ALICE particle ID performances • Unique capability to identify and reconstruct particles • - “stable particles” through dE/dx (TPC+ITS) + TOF + Cherenkov (HMPID) • π, k, p : 0.15 – 5 GeV/c -> 50 GeV/c (relativistic rise) • Invariant mass reconstruction already done for many resonances and strange weak decaying hadrons (K0s, , , ) L Pt limits for 107 central Pb-Pb events (1-year data taking) f (1020)  K+K- A. Mastroserio - XLIIIth Rencontres de Moriond

10. High PT probes A. Mastroserio - XLIIIth Rencontres de Moriond

11. High PT probes • What if QGP is formed: • Partons propagate in a hot and dense medium before fragmenting in the vacuum • E loss medium > E lossvacuum and depends on the the length of the traversed medium • High pT hadrons are suppressed • “Jet quenching” -> q [medium dependent] QGP probes: inclusive hadron yields at high pT, Jet Structure A. Mastroserio - XLIIIth Rencontres de Moriond

12. Inclusive hadron yields Factor 5 suppression @RHIC: RAA ~ 0.2 constant at pT > 5 GeV/c • Possible LHC scenario: • - light flavour RAA • - constant ~0.1 at 10< pT (GeV/c) < 20 (gluon dominance) • - slow rise up to 0.2 at 20 < pT (GeV/c)< 100 • [arXiv:0707.0564v1 [hep-ph] and arXiv:0711.0974v1 [hep-ph] • - slow rise to 0.4 up to pT < 400 GeV/c • [arXiv:0711.0974v1 [hep-ph] ] • Heavy flavour / light flavour RAA : • - D quenching vs h quenching probes color charge • dependence (ΔEQ < ΔE g) • - B quenching vs D quenching probes parton mass • dependence of parton E loss A. Mastroserio - XLIIIth Rencontres de Moriond

13. Jet physics in HI Jet in QCD: cascades of consecutive emissions of partons initiated by partons from an initial hard scattering • What if QGP is formed: • The initial energy of fast partons is degraded in the medium • Broadening of the parton shower along the fast parton direction • Modified jet structure and fragmentation functions N. Borghini & U. Wiedemann A. Mastroserio - XLIIIth Rencontres de Moriond

14. GeV2/fm [AQM] Jet Reconstruction: RAA(x) e-by-e jet reconstruction feasible A. Morsch @ QM08 A. Mastroserio - XLIIIth Rencontres de Moriond

15. Summary • ALICE is a versatile experiment which will study the QGP formation in different physics domains (statisical thermodynamics, hydrodynamics, pQCD,etc.) • Only few topics of the ALICE Heavy Ion Physics programme have been shown! • first 105 events: global event properties • multiplicity, rapidity density • elliptic flow • first 106 events: source characteristics • particle spectra, resonances • flow analysis • interferometry • first 107 events: high-pt, heavy flavours • jet quenching, heavy-flavour energy loss • first 108 events: heavy quark production • J/Ψ,  -> initial conditions -> chemical equilibrium -> Parton E loss in the medium A. Mastroserio - XLIIIth Rencontres de Moriond

16. ALICE start up configuration • complete – fully installed & commissioned • ITS, TPC, TOF, HMPID, MUON SPECTROM., PMD, V0, T0, FMD, ZDC, ACORDE • partially completed • TRD (25%) to be completed by 2009 • PHOS (60%) to be completed by 2010 • HLT (30%) to be completed by 2009 • EMCAL (0%) to be completed by 2010/11 • at start-up full hadron and muon capabilities • partial electron and photon capabilities ….looking forward to “detect” this! A. Mastroserio - XLIIIth Rencontres de Moriond

17. A. Mastroserio - XLIIIth Rencontres de Moriond

18. Bkp slides A. Mastroserio - XLIIIth Rencontres de Moriond

19. QGP in lQCD A. Mastroserio - XLIIIth Rencontres de Moriond

20. HI collisions from SPS to LHC Phase transition (lattice QCD): Tcr ~ 170 MeV εcr~ 1 GeV/fm3 • New scenario: • Hard processes dominate AA cross section • QGP at LHC > RHIC : parton dynamics dominate the fireball expansion A. Mastroserio - XLIIIth Rencontres de Moriond

21. Alice ID A. Mastroserio - XLIIIth Rencontres de Moriond

22. Hadron ratios Non equilibrium Chemical equilibrium A. Mastroserio - XLIIIth Rencontres de Moriond

23. Strangeness production in HI • - No initial net strangeness • strange particle are a direct • consequence of the collision • dynamics Strangeness production mechanism is in the QGP phase: gg-> s sbar (no hadron mass thresholds to be overcome! ) arXiv:0705.2511v1 [nucl-ex] 17 May 2007 A. Mastroserio - XLIIIth Rencontres de Moriond

24. 1 year data taking >107 Background ~ R2 — no pT cut — pT >1 GeV/c — pT >2 GeV/c E(R), charged [GeV] ETjet 150 GeV 100 GeV 50 GeV 30 GeV R Jets A. Mastroserio - XLIIIth Rencontres de Moriond

25. LHC rates and HQ σ A. Mastroserio - XLIIIth Rencontres de Moriond