8-12 Feb. 2007Yves ICPAQGP51 Heavy-ion physics at LHC New states of matter ? (QGP, sQGP, bsQGP, CGC,…) New probes

8-12 Feb. 2007Yves ICPAQGP52 SPS: ”New State of Matter created at CERN” (10 Feb. 2000) 7 dedicated experiments (NAxx, WAyy) Compelling evidence for the existence of a new state of matter (   3.2 GeV/fm 3 ] >  c, strangeness enhancement, J/ψ suppression, direct thermal photon radiation,…) Interpretation in terms of QGP formation not unique Pb+Pb √s NN = 17.3 GeV NA 49

8-12 Feb. 2007Yves ICPAQGP53 RHIC: “The discovery of the QGP at RHIC” (M. Gyulassy QM 2004) 4 multipurpose experiments (BRAHMS, PHENIX, PHOBOS, STAR) Empirical lines of evidence:  Energy density (5 GeV/fm 3 ) 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 (?) C olor G lass C ondensate Au+Au √s NN = 200 GeV STAR

8-12 Feb. 2007Yves ICPAQGP54 LHC: “The closest approximation of the Big Bang” (J. Ellis 02/2005) One heavy ion experiment, ALICE, + CMS & ATLAS; In 04/2007, LHC will deliver first pp at 14 TeV collisions, and soon after PbPb collisions at √s NN = 5.5 TeV. “It is dangerous to make predictions, especially about the future." G. Marx

8-12 Feb. 2007Yves ICPAQGP55 What will be new at LHC SPSRHICLHC √s NN (GeV)17200 dN ch /dy  0 QGP (fm/c) 10.2 T/T c  (GeV/fm 3 ) 35  QGP (fm/c) ≤22-4  f (fm/c) ~ V f (fm 3 )few 10 3 few 10 4 few 10 5 bigger 5500X ? 0.1faster hotter 15-60denser ≥10 longer “The biggest step in energy in the history of heavy-ion collisions” G. Rolland

8-12 Feb. 2007Yves ICPAQGP56 Formation of the real vacuum of QCD Weakly interacting gas of mass less quarks (3 flavors) and gluons with restored Chiral symmetry m u = m d = m s m u = m d m u = m d ; m s  m u,d HQ suppressed exp(-m c,b,t /T)  s (T)=4  /(18log(5T/Tc)) RHIC SPS LHC Not yet a S tefan B oltzmann gas

8-12 Feb. 2007Yves ICPAQGP57 A new kinematical regime X<<1  Determines the properties of the medium (Q S =0.2A 1/6 √s  = 2.7 GeV)  The QGP at LHC might evolve from a Color Glass Condensate in the initial state of the collision J/ψ ALICE PPR CERN/LHCC ² x Q 2 (GeV 2 ) 100 GeV “LHC: The color glass machine” L. McLerran

8-12 Feb. 2007Yves ICPAQGP58 A new kinematical regime Q >> 1  Determines the probe of the medium  Q >>  QCD, T ( ,  r ~1/Q) ; p t > 2 GeV/c

8-12 Feb. 2007Yves ICPAQGP59 Hard probes 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 LHC:  hard /  total = 98% (50% at RHIC)

8-12 Feb. 2007Yves ICPAQGP510 Dynamics of hadronisation : in vacuum The medium modifies the vacuum dynamics Modifications are imprinted in the hadronic final state ETET hadronic final state L hadr ~ E T /Q 2 hadr

8-12 Feb. 2007Yves ICPAQGP511 Dynamics of hadronisation: in medium The radiated energy (  E) depends on the properties of the medium (the transport coefficient q ) The competition between thermalisation (  E=E) and hadronisation depends on the hard parton transverse energy. ETET hadronic final state L hadr ~ E T /Q 2 hadr EE L therm ~ √(E T /q ) ^ ^

8-12 Feb. 2007Yves ICPAQGP512 Dynamics of hadronisation: in medium L therm < L hadr < L medium  The hard parton is thermalised in the heat bath  Bulk properties of the medium from low p h t ( ≤ 2 GeV/c) hadrons, leptons, photons ETET  E ~ E T Experimental requirements: low p t threshold

8-12 Feb. 2007Yves ICPAQGP513 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) 150

8-12 Feb. 2007Yves ICPAQGP514 Dynamics of hadronisation: in medium L therm ~ L hadr ~ L medium  The medium is a tool to modify the hadronisation process  Dynamics of hadronisation (p h t ~2-7 GeV/c) ETET hadronic final state L hadr ~ E T /Q 2 hadr EE L therm ~ √(E T /q ) ^

8-12 Feb. 2007Yves ICPAQGP515 Medium modified fragmentation Fragmentation, recombination ? Experimental requirements: PID up to ~ 10 GeV/c p/  P t [GeV/c]

8-12 Feb. 2007Yves ICPAQGP516 Dynamics of hadronisation: in medium L therm > L hadr > L medium  The parton looses additional energy ( qL 2 )  The multiplicity, transverse momentum of the shower broadens ( qL )  Leading hadron ETET hadronic final state EE L therm ~ √(E T /q ) ^ ^ ^ xE T

8-12 Feb. 2007Yves ICPAQGP517 Leading hadron (qL 2 ) 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 Eskola, Honkanen, Salgado, Wiedemann Nucl Phys A, hep-ph/ Experimental requirements: high p t ^ q=5 GeV 2 /fm ^ q=10 GeV 2 /fm ^

8-12 Feb. 2007Yves ICPAQGP518 Mass and color charge dependence Experimental requirements: high p t electrons, vertexing ArmestoArmesto, Dainese, Salgado, Wiedemann hep-ph/ Dainese SalgadoWiedemann “Death of the dead cone”, I. Vitev

8-12 Feb. 2007Yves ICPAQGP519 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 ^

8-12 Feb. 2007Yves ICPAQGP520 Jet heating Sensitivity of jet energy distribution weak Broadening of k t Modified longitudinal fragmentation function:  (Z)-jet tagging Salgado, Wiedemann, hep-ph/ k t

8-12 Feb. 2007Yves ICPAQGP521  -jet tagging Pb+Pb 40GeV →  -jet R=0.3; p t > 2 GeV/c E jet /E  x T =p T /E  R AA Experimental requirements: jet calorimetry, low x t hadrons, high p t , e

8-12 Feb. 2007Yves ICPAQGP experiments at the LHC ATLAS CMS ALICE

8-12 Feb. 2007Yves ICPAQGP523 ALICE Physics Program Deconfinement:  charmonium and bottomium spectroscopy Energy loss of partons in quark gluon plasma:  jet quenching high p t 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

8-12 Feb. 2007Yves ICPAQGP524 Heavy ion experiment at LHC ALICE will meet the challenge to measure flavor content and phase-space distribution event-by- event:  Most (2  * 1.8 units  ) 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 GeV/c; hard processes);  Identify short lived particles (hyperons, D/B meson) through secondary vertex detection;  Identify jets;

8-12 Feb. 2007Yves ICPAQGP525 ALICE: the dedicated HI experiment Solenoid magnet 0.5 T Central tracking system: ITS TPC TRD TOF MUON Spectrometer: absorbers tracking stations trigger chambers dipole Specialized detectors: HMPID PHOS Forward detectors: PMD FMD, T0, V0, ZDC Cosmic rays trigger

8-12 Feb. 2007Yves ICPAQGP526 Proposed ALICE EMCAL EM Sampling Calorimeter (STAR Design) Pb-scintillator linear response  -0.7 <  < 0.7   /3 <  <  Energy resolution ~15%/√E

8-12 Feb. 2007Yves ICPAQGP527 Alice uses ~all known techniques! p (GeV/c) p (GeV/c) TRD e /  PHOS  /  0 TPC + ITS (dE/dx)  /K K/p e /  HMPID (RICH) TOF Aerogel Cherenkov 10 GeV/c ALICE PID EMCAL

8-12 Feb. 2007Yves ICPAQGP528 Jet Phase Space p t (GeV/c) Bulk properties Hard processes Modified by the medium T=  QCD QsQs ALICE Tracking & PID Jets from Correlations and Leading Particles Reconstructed Jets Mini-jets 100/event 1/event 100K/year CMS&ATLAS calorimetry “Jet physics will dominate the LHC heavy-ion program”, ALICE will be the main contender of the “race for jet quenching” I. Vitev

8-12 Feb. 2007Yves ICPAQGP529 LHC

8-12 Feb. 2007Yves ICPAQGP530 LHC

8-12 Feb. 2007Yves ICPAQGP531 ATLAS

8-12 Feb. 2007Yves ICPAQGP532 CMS

8-12 Feb. 2007Yves ICPAQGP533 ALICE

8-12 Feb. 2007Yves ICPAQGP534 More at ICPAQGP6 The first 15 minutes; L int =1  b -1  Event multiplicity, low p t hadronic spectra, particle ratios The first month; L int =0.1-1nb -1  Rare high p t processes: jets, D,B, quarkonia, photons, electrons The following years:  pA, A scan, E scan  PbPb = 8barn; L PbPb cm -2 s -1 ; t 0 =04/2007