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ALICE at LHC

ALICE at LHC. New states of matter ? (QGP, wQGP, sQGP, bsQGP, CGC,…) New probes. “ LHC not relevant for the search of the critical point ” Marek Gazdzicki. 7 dedicated experiments (NAxx, WAyy)

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ALICE at LHC

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  1. ALICE at LHC New states of matter ? (QGP, wQGP, sQGP, bsQGP, CGC,…) New probes “LHC not relevant for the search of the critical point” Marek Gazdzicki Yves Schutz @ 2nd International workshop on the Critical Point and onset of deconfinement

  2. 7 dedicated experiments (NAxx, WAyy) Compelling evidence for the existence of a new state of matter(e [3.2 GeV/fm3]>ec, strangeness enhancement, J/ψsuppression, direct thermal photon radiation,…) Interpretation in terms of QGP formation not unique SPS: ”New State of Matter created at CERN”(10 Feb. 2000) Pb+Pb √sNN = 17.3 GeV NA 49 Yves Schutz @ 2nd International workshop on the Critical Point and onset of deconfinement

  3. RHIC: “The discovery of the QGP at RHIC”(M. Gyulassy QM 2004) Au+Au √sNN = 200 GeV STAR • 4 multipurpose experiments (BRAHMS, PHENIX, PHOBOS, STAR) • Empirical lines of evidence: • Energy density (5 GeV/fm3) well beyond critical value • Large elliptic flow: early collective behavior at partonic level • Jet quenching, mono jets: absorption of partons in a color dense opaque medium • dA control experiment • Interpreted in terms of a strongly coupled QGP and a new QCD state (?) Color Glass Condensate Yves Schutz @ 2nd International workshop on the Critical Point and onset of deconfinement

  4. LHC: “The closest approximation of the Big Bang” “It is dangerous to make predictions, especially about the future." • One heavy ion experiment, ALICE • In 04/2007, LHC will deliver first pp at 14 TeV collisions, • and soon after PbPb collisions at √sNN= 5.5 TeV. Yves Schutz @ 2nd International workshop on the Critical Point and onset of deconfinement

  5. What will be new at LHC “The biggest step in energy in the history of heavy-ion collisions” Yves Schutz @ 2nd International workshop on the Critical Point and onset of deconfinement

  6. Formation of the real vacuum of QCD • Weakly interacting gas of mass less quarks (3 flavors) and gluons with restored Chiral symmetry Not yet a StefanBoltzmann gas RHIC as(T)=4p/(18log(5T/Tc)) LHC SPS mu= md = ms mu = md mu = md ; ms mu,d HQ suppressed exp(-mc,b,t/T) Yves Schutz @ 2nd International workshop on the Critical Point and onset of deconfinement

  7. 100 GeV 10-6 10-4 10-2 100 x J/ψ A new kinematical regime 108 106 104 102 100 • x<<1 • Determines the properties of the medium (QS=0.2A1/6√sd= 2.7 GeV) • The QGP at LHC might evolve from a Color Glass Condensate in the initial state of the collision Q2 (GeV2) “LHC: The color glass machine” L. McLerran  ALICE PPR CERN/LHCC 2003-049² Yves Schutz @ 2nd International workshop on the Critical Point and onset of deconfinement

  8. 108 106 104 102 100 Q2 (GeV2) 100 GeV 10-6 10-4 10-2 100 x J/ψ ALICE PPR CERN/LHCC 2003-049² A new kinematical regime • Q >> 1 • Determines the probe of the medium • Q >>LQCD, T (Dt, Dr ~1/Q) ; pt >2 GeV/c Yves Schutz @ 2nd International workshop on the Critical Point and onset of deconfinement

  9. (h++h-)/2 p0 √s = 5500 GeV 200 GeV LO p+p y=0 17 GeV LHC RHIC SPS Hard probes LHC: shard/stotal = 98% (50% at RHIC) • Particle production dominated by hard processes • Heavy quarks and weakly interacting probes become accessible • Happen at t=0 → initial stage of the collision • Have a large virtuality → short formation time • Probe matter at very early times → QGP • Can be calculated by pQCD → predictions Yves Schutz @ 2nd International workshop on the Critical Point and onset of deconfinement

  10. Dynamics of hadronisation : in vacuum • The medium modifies the vacuum dynamics • Modifications are imprinted in the hadronic final state hadronic final state ET Lhadr ~ ET/Q2hadr Yves Schutz @ 2nd International workshop on the Critical Point and onset of deconfinement

  11. ^ Ltherm ~ √(ET/q ) DE Dynamics of hadronisation: in medium • The radiated energy (DE) depends on the properties of the medium (the transport coefficient q) • The competition between thermalisation (DE=E) and hadronisation depends on the hard parton transverse energy. hadronic final state ET Lhadr ~ ET/Q2hadr ^ Yves Schutz @ 2nd International workshop on the Critical Point and onset of deconfinement

  12. DE ~ ET Experimental requirements: low pt threshold Dynamics of hadronisation: in medium • Ltherm< Lhadr < Lmedium • The hard parton is thermalisedin the heat bath • Bulk properties of the medium from low pht ( ≤ 2 GeV/c) hadrons, leptons, photons ET Yves Schutz @ 2nd International workshop on the Critical Point and onset of deconfinement

  13. 150 Bulk properties of the LHC medium • Monotonic extrapolation from RHIC but changes in • Expansion dynamics and (elliptic flow, transverse volume, event by event fluctuations, …) • Freeze out (temperature, charm, …) • Thermal photons (real & virtual) Yves Schutz @ 2nd International workshop on the Critical Point and onset of deconfinement

  14. ^ Ltherm ~ √(ET/q ) DE Dynamics of hadronisation: in medium • Ltherm~ Lhadr ~ Lmedium • The medium is a tool to modify the hadronisation process • Dynamics of hadronisation (pht ~2-7 GeV/c) hadronic final state ET Lhadr ~ ET/Q2hadr Yves Schutz @ 2nd International workshop on the Critical Point and onset of deconfinement

  15. Fragmentation, recombination ? Experimental requirements: PID up to ~ 10 GeV/c Medium modified fragmentation p/p Pt[GeV/c] Yves Schutz @ 2nd International workshop on the Critical Point and onset of deconfinement

  16. ^ Ltherm ~ √(ET/q ) DE Dynamics of hadronisation: in medium • Ltherm> Lhadr > Lmedium • The parton looses additional energy (qL2) • The multiplicity, transverse momentum of the shower broadens (qL) • Leading hadron xET hadronic final state ET ^ ^ Yves Schutz @ 2nd International workshop on the Critical Point and onset of deconfinement

  17. ^ ^ q=5 GeV2/fm q=10 GeV2/fm Experimental requirements: high pt Leading hadron (qL2) ^ Eskola, Honkanen, Salgado, Wiedemann Nucl Phys A, hep-ph/0406319 • Probe the reduced energy of the parton with the reduced energy of the leading hadron. • … But surface emission limits the sensitivity to the medium properties Yves Schutz @ 2nd International workshop on the Critical Point and onset of deconfinement

  18. Armesto, Dainese, Salgado, Wiedemann hep-ph/0501225 Experimental requirements: high pt electrons, vertexing Mass and color charge dependence Yves Schutz @ 2nd International workshop on the Critical Point and onset of deconfinement

  19. Jet heating (qL) ^ • At LHC jets can be reconstructed in the HI environment • The measurement of the jet structure provides a better sensitivity to the medium properties Yves Schutz @ 2nd International workshop on the Critical Point and onset of deconfinement

  20. Salgado, Wiedemann, hep-ph/0310079 Jet heating • Sensitivity of jet energy distribution weak • Broadening of kt • Modified longitudinal fragmentation function: g(Z)-jet tagging . kt Yves Schutz @ 2nd International workshop on the Critical Point and onset of deconfinement

  21. RAA Experimental requirements: jet calorimetry, low xt hadrons, high ptg, e xT=pT/Eg g-jet tagging Pb+Pb 40GeV →g-jet R=0.3; pt> 2 GeV/c Ejet/Eg Yves Schutz @ 2nd International workshop on the Critical Point and onset of deconfinement

  22. 1+2 experiments at the LHC ALICE ATLAS CMS Yves Schutz @ 2nd International workshop on the Critical Point and onset of deconfinement

  23. ALICE Physics Program • Deconfinement: • charmonium and bottomonium spectroscopy • Energy loss of partons in quark gluon plasma: • jet quenching high pt spectra • open charm and open beauty • Chiral symmetry restoration: • neutral to charged ratios • resonance decays • Fluctuation phenomena - critical behavior: • event-by-event (√N) particle composition and spectra • pp collisions in a new energy domain Yves Schutz @ 2nd International workshop on the Critical Point and onset of deconfinement

  24. Heavy ion experiment at LHC • ALICE will meet the challenge to measure flavor content and phase-space distribution event-by-event: • Most (2p * 1.8 units h) of the hadrons (dE/dx + ToF), leptons (dE/dx, transition radiation, magnetic analysis) and photons (high resolution EM calorimetry); • Track and identify from very low (< 100 MeV/c; soft processes) up to very high pt(>100 GeV/c; hard processes); • Identify short lived particles (hyperons, D/B meson) through secondary vertex detection; • Identify jets; Yves Schutz @ 2nd International workshop on the Critical Point and onset of deconfinement

  25. Aerogel Cherenkov 10 GeV/c ALICE PID Alice uses ~all known techniques! p/K TPC + ITS (dE/dx) K/p e /p p/K e /p TOF K/p p/K HMPID (RICH) K/p 0 1 2 3 4 5 p (GeV/c) TRD e /p PHOS g /p0 EMCAL 1 10 100 p (GeV/c) Yves Schutz @ 2nd International workshop on the Critical Point and onset of deconfinement

  26. 0 1 2 10 100 pt (GeV/c) Jet Phase Space Jet physics will dominate the LHC heavy-ion program, ALICE will be the main contender of the race for jet quenching Qs T=LQCD Mini-jets 100/event 100K/year 1/event Bulk properties Hard processes Modified by the medium ALICE Tracking & PID Jets from Correlations and Leading Particles Reconstructed Jets Yves Schutz @ 2nd International workshop on the Critical Point and onset of deconfinement

  27. ALICE Yves Schutz @ 2nd International workshop on the Critical Point and onset of deconfinement

  28. The ALICE program in 2007 on wards • The first 15 minutes; Lint=1mb-1 • Event multiplicity, low pt hadronic spectra, particle ratios • The first month; Lint=0.1-1nb-1 • Rare high pt processes: jets, D,B, quarkonia, photons, electrons • The following years: • pA, A scan, E scan sPbPb = 8barn; LPbPb 1027cm-2s-1; t0=04/2007 Yves Schutz @ 2nd International workshop on the Critical Point and onset of deconfinement

  29. Yves Schutz @ 2nd International workshop on the Critical Point and onset of deconfinement

  30. ALICE: the dedicated HI experiment Solenoid magnet 0.5 T Cosmic rays trigger • Forward detectors: • PMD • FMD, T0, V0, ZDC • Specialized detectors: • HMPID • PHOS • Central tracking system: • ITS • TPC • TRD • TOF • MUON Spectrometer: • absorbers • tracking stations • trigger chambers • dipole Yves Schutz @ 2nd International workshop on the Critical Point and onset of deconfinement

  31. Proposed ALICE EMCAL • EM Sampling Calorimeter (STAR Design) • Pb-scintillator linear response • -0.7 < h < 0.7 • p/3 < F < p • Energy resolution ~15%/√E Yves Schutz @ 2nd International workshop on the Critical Point and onset of deconfinement

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