1. New states of matter ? (QGP, wQGP, sQGP, bsQGP, CGC,…) New probes
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
30 March -3 April 2005
Yves 2nd International workshop on the Critical Point and onset of deconfinement

2. SPS: ”New State of Matter created at CERN” (10 Feb. 2000)
Pb+Pb √sNN = 17.3 GeV
NA 49
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/ψ suppression, direct thermal photon radiation,…)
Interpretation in terms of QGP formation not unique
30 March -3 April 2005
Yves 2nd International workshop on the Critical Point and onset of deconfinement

3. 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/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
Au+Au √sNN = 200 GeV
STAR
30 March -3 April 2005
Yves 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.
I will not say what LHC will discovwe, because, as Groucho Marx once said, "It is dangerous to make predictions, especially about the future." However, I am sure that something new will
30 March -3 April 2005
Yves 2nd International workshop on the Critical Point and onset of deconfinement

5. What will be new at LHC few 105 bigger ≥10 longer 30-40 15-60 denser
0.1
faster
hotter ?
5500
X 28
SPS
RHIC
LHC
√sNN (GeV) 17
200
dNch/dy
500
850
t0QGP (fm/c) 1
0.2
T/Tc
1.1
1.9
e (GeV/fm3) 3 5
tQGP (fm/c) ≤2
2-4
tf (fm/c)
~10
20-30
Vf(fm3)
few 103
few 104
“The biggest step in energy in the history of heavy-ion collisions”
30 March -3 April 2005
Yves 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)
30 March -3 April 2005
Yves 2nd International workshop on the Critical Point and onset of deconfinement

7. 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)
100 GeV
J/ψ
“LHC: The color glass machine”
L. McLerran  x
ALICE PPR CERN/LHCC ²
30 March -3 April 2005
Yves 2nd International workshop on the Critical Point and onset of deconfinement

8. A new kinematical regime
J/ψ
ALICE PPR CERN/LHCC ² x
108
106
104
102
100
Q2 (GeV2)
100 GeV
Q >> 1
Determines the probe of the medium
Q >> LQCD, T (Dt, Dr ~1/Q) ; pt > 2 GeV/c
30 March -3 April 2005
Yves 2nd International workshop on the Critical Point and onset of deconfinement

9. Hard probes LHC: shard/stotal = 98% (50% at RHIC) LHC
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
RHIC
SPS
(h++h-)/2 p0
17 GeV
200 GeV
5500 GeV = √s
LO p+p y=0
30 March -3 April 2005
Yves 2nd International workshop on the Critical Point and onset of deconfinement

10. Dynamics of hadronisation : in vacuum
hadronic final state ET
Lhadr ~ ET/Q2hadr
The medium modifies the vacuum dynamics
Modifications are imprinted in the hadronic final state
30 March -3 April 2005
Yves 2nd International workshop on the Critical Point and onset of deconfinement

11. Dynamics of hadronisation: in mediumDE
Ltherm ~ √(ET/q ) ^
hadronic final state ET
Lhadr ~ ET/Q2hadr
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. ^
30 March -3 April 2005
Yves 2nd International workshop on the Critical Point and onset of deconfinement

12. Dynamics of hadronisation: in medium
DE ~ ET ET
Ltherm< Lhadr < Lmedium
The hard parton is thermalised in the heat bath
Bulk properties of the medium from low pht ( ≤ 2 GeV/c) hadrons, leptons, photons
Experimental requirements: low pt threshold
30 March -3 April 2005
Yves 2nd International workshop on the Critical Point and onset of deconfinement

13. 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
30 March -3 April 2005
Yves 2nd International workshop on the Critical Point and onset of deconfinement

14. Dynamics of hadronisation: in mediumDE
Ltherm ~ √(ET/q ) ^
hadronic final state ET
Lhadr ~ ET/Q2hadr
Ltherm~ Lhadr ~ Lmedium
The medium is a tool to modify the hadronisation process
Dynamics of hadronisation (pht ~2-7 GeV/c)
30 March -3 April 2005
Yves 2nd International workshop on the Critical Point and onset of deconfinement

15. Medium modified fragmentation
p/p
Pt[GeV/c]
Fragmentation, recombination ?
Experimental requirements: PID up to ~ 10 GeV/c
30 March -3 April 2005
Yves 2nd International workshop on the Critical Point and onset of deconfinement

16. Dynamics of hadronisation: in mediumDE
Ltherm ~ √(ET/q ) ^
xET
hadronic final state ET
Ltherm> Lhadr > Lmedium
The parton looses additional energy (qL2)
The multiplicity, transverse momentum of the shower broadens (qL)
Leading hadron ^ ^
30 March -3 April 2005
Yves 2nd International workshop on the Critical Point and onset of deconfinement

17. Leading hadron (qL2) ^ ^ q=5 GeV2/fm ^ q=10 GeV2/fm
Eskola, Honkanen, Salgado, Wiedemann
Nucl Phys A, hep-ph/
q=5 GeV2/fm ^
q=10 GeV2/fm ^
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
Experimental requirements: high pt
30 March -3 April 2005
Yves 2nd International workshop on the Critical Point and onset of deconfinement

18. Mass and color charge dependence
Armesto, Dainese, Salgado, Wiedemann hep-ph/
Experimental requirements: high pt electrons, vertexing
30 March -3 April 2005
Yves 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
30 March -3 April 2005
Yves 2nd International workshop on the Critical Point and onset of deconfinement

20. Jet heating . kt Sensitivity of jet energy distribution weak
Salgado, Wiedemann,
hep-ph/
. kt
Sensitivity of jet energy distribution weak
Broadening of kt
Modified longitudinal fragmentation function: g(Z)-jet tagging
30 March -3 April 2005
Yves 2nd International workshop on the Critical Point and onset of deconfinement

21. g-jet tagging RAA Pb+Pb 40GeV → g-jet R=0.3; pt> 2 GeV/c Ejet/Eg
xT=pT/Eg
RAA
Pb+Pb 40GeV → g-jet
R=0.3; pt> 2 GeV/c
Ejet/Eg
Experimental requirements: jet calorimetry, low xt hadrons, high pt g, e
30 March -3 April 2005
Yves 2nd International workshop on the Critical Point and onset of deconfinement

22. 1+2 experiments at the LHC
ATLAS
ALICE
CMS
30 March -3 April 2005
Yves 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
30 March -3 April 2005
Yves 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;
30 March -3 April 2005
Yves 2nd International workshop on the Critical Point and onset of deconfinement

25. ALICE PID Alice uses ~all known techniques! Aerogel Cherenkov
TPC + ITS
(dE/dx)
p/K
K/p
e /p
p/K
TOF
e /p
K/p
HMPID
(RICH)
p/K
K/p
p (GeV/c)
Aerogel Cherenkov
10 GeV/c
TRD e /p
PHOS g /p0
EMCAL
p (GeV/c)
30 March -3 April 2005
Yves 2nd International workshop on the Critical Point and onset of deconfinement

26. Jet Phase Space 1 2 10 100 pt (GeV/c) T=LQCD Qs Bulk properties
Jet physics will dominate the LHC heavy-ion program, ALICE will be the main contender of the race for jet quenching
Jet Phase Space 1 2 10
100
pt (GeV/c)
T=LQCD Qs
Mini-jets 100/event
1/event
100K/year
Bulk properties
Hard processes
Modified by the medium
ALICE Tracking & PID
Jets from Correlations and Leading Particles
Reconstructed Jets
30 March -3 April 2005
Yves 2nd International workshop on the Critical Point and onset of deconfinement

27. ALICE
30 March -3 April 2005
Yves 2nd International workshop on the Critical Point and onset of deconfinement

28. The ALICE program in 2007 on wards
sPbPb = 8barn; LPbPb 1027cm-2s-1; t0=04/2007
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
30 March -3 April 2005
Yves 2nd International workshop on the Critical Point and onset of deconfinement

29. 30 March -3 April 2005
Yves 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
ALICE: the dedicated HI experiment
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
30 March -3 April 2005
Yves 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
30 March -3 April 2005
Yves 2nd International workshop on the Critical Point and onset of deconfinement