8-12 Feb. 2007Yves Schutz @ ICPAQGP51 Heavy-ion physics at LHC New states of matter ? (QGP, sQGP,...
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Transcript of 8-12 Feb. 2007Yves Schutz @ ICPAQGP51 Heavy-ion physics at LHC New states of matter ? (QGP, sQGP,...
8-12 Feb. 2007 Yves Schutz @ ICPAQGP5 1
Heavy-ion physics at LHC
New states of matter ? (QGP, sQGP, bsQGP, CGC,…)
New probes
8-12 Feb. 2007 Yves Schutz @ ICPAQGP5 2
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/fm3]>c, strangeness enhancement, J/ψ suppression, direct thermal photon radiation,…)
Interpretation in terms of QGP formation not unique
Pb+Pb √sNN = 17.3 GeV NA 49
8-12 Feb. 2007 Yves Schutz @ ICPAQGP5 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 GeVSTAR
8-12 Feb. 2007 Yves Schutz @ ICPAQGP5 4
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 √sNN= 5.5 TeV.
“It is dangerous to make predictions, especially about the future." G. Marx
8-12 Feb. 2007 Yves Schutz @ ICPAQGP5 5
What will be new at LHC
SPS RHIC LHC
√sNN (GeV) 17 200
dNch/dy 500 850
0QGP (fm/c) 1 0.2
T/Tc 1.1 1.9
(GeV/fm3) 3 5
QGP (fm/c) ≤2 2-4
f (fm/c) ~10 20-30
Vf(fm3) few 103 few 104
few 105 bigger
5500 X 28
1000-4000 ?
0.1 faster
3.0-4.2 hotter
15-60 denser
≥10longer
30-40
“The biggest step in energy in the history of heavy-ion collisions” G. Rolland
8-12 Feb. 2007 Yves Schutz @ ICPAQGP5 6
Formation of the real vacuum of QCD
Weakly interacting gas of mass less quarks (3 flavors) and gluons with restored Chiral symmetry
mu= md = ms
mu = md
mu = md ; ms mu,d
HQ suppressed exp(-mc,b,t/T)
s(T)=4/(18log(5T/Tc))
RHIC
SPS
LHC
Not yet a StefanBoltzmann gas
8-12 Feb. 2007 Yves Schutz @ ICPAQGP5 7
A new kinematical regime
X<<1 Determines the properties of
the medium (QS=0.2A1/6√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 2003-049²
10-6 10-4 10-2 100
x
108
106
104
102
100
Q2 (
GeV
2)
100 GeV
“LHC: The color glass machine”L. McLerran
8-12 Feb. 2007 Yves Schutz @ ICPAQGP5 8
A new kinematical regime
Q >> 1 Determines the probe of the
medium Q >> QCD, T (, r ~1/Q) ;
pt > 2 GeV/c
J/ψ
ALICE PPR CERN/LHCC 2003-049²
10-6 10-4 10-2 100
x
108
106
104
102
100
Q2 (
GeV
2)
100 GeV
8-12 Feb. 2007 Yves Schutz @ ICPAQGP5 9
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
RHICSPS
(h++h-)/2
0
17 GeV
200 GeV
5500 GeV=√s
LO p+p y=0
LHC:hard/total = 98% (50% at RHIC)
8-12 Feb. 2007 Yves Schutz @ ICPAQGP5 10
Dynamics of hadronisation : in vacuum
The medium modifies the vacuum dynamics Modifications are imprinted in the hadronic final state
ET
hadronic final state
Lhadr ~ ET/Q2hadr
8-12 Feb. 2007 Yves Schutz @ ICPAQGP5 11
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.
ET
hadronic final state
Lhadr ~ ET/Q2hadr
E Ltherm ~ √(ET/q )^
^
8-12 Feb. 2007 Yves Schutz @ ICPAQGP5 12
Dynamics of hadronisation: in medium
Ltherm< Lhadr < Lmedium
The hard parton is thermalised in the heat bath Bulk properties of the medium from low ph
t ( ≤ 2 GeV/c) hadrons, leptons, photons
ET
E ~ ET
Experimental requirements: low pt threshold
8-12 Feb. 2007 Yves Schutz @ ICPAQGP5 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
8-12 Feb. 2007 Yves Schutz @ ICPAQGP5 14
Dynamics of hadronisation: in medium
Ltherm~ Lhadr ~ Lmedium
The medium is a tool to modify the hadronisation process Dynamics of hadronisation (ph
t ~2-7 GeV/c)
ET
hadronic final state
Lhadr ~ ET/Q2hadr
E Ltherm ~ √(ET/q )^
8-12 Feb. 2007 Yves Schutz @ ICPAQGP5 15
Medium modified fragmentation
Fragmentation, recombination ?
Experimental requirements: PID up to ~ 10 GeV/c
p/
Pt[GeV/c]
8-12 Feb. 2007 Yves Schutz @ ICPAQGP5 16
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
ET
hadronic final state
E Ltherm ~ √(ET/q )^
^
^
xET
8-12 Feb. 2007 Yves Schutz @ ICPAQGP5 17
Leading hadron (qL2)
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/0406319
Experimental requirements: high pt
^
q=5 GeV2/fm^
q=10 GeV2/fm^
8-12 Feb. 2007 Yves Schutz @ ICPAQGP5 18
Mass and color charge dependence
Egluon Equark,m0 Equark,m0
Experimental requirements: high pt electrons, vertexing
Armesto, Dainese, Salgado, Wiedemann hep-ph/0501225
“Death of the dead cone”, I. Vitev
8-12 Feb. 2007 Yves Schutz @ ICPAQGP5 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
^
8-12 Feb. 2007 Yves Schutz @ ICPAQGP5 20
Jet heating
Sensitivity of jet energy distribution weak Broadening of kt
Modified longitudinal fragmentation function: (Z)-jet tagging
Salgado, Wiedemann, hep-ph/0310079
. kt
8-12 Feb. 2007 Yves Schutz @ ICPAQGP5 21
-jet tagging
Pb+Pb 40GeV → -jetR=0.3; pt> 2 GeV/c
Ejet/E xT=pT/E
RAA
Experimental requirements: jet calorimetry, low xt hadrons, high pt , e
8-12 Feb. 2007 Yves Schutz @ ICPAQGP5 22
1+2 experiments at the LHCATLASCMSALICE
8-12 Feb. 2007 Yves Schutz @ ICPAQGP5 23
ALICE Physics Program
Deconfinement: charmonium and bottomium 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
8-12 Feb. 2007 Yves Schutz @ ICPAQGP5 24
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 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;
8-12 Feb. 2007 Yves Schutz @ ICPAQGP5 25
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. 2007 Yves Schutz @ ICPAQGP5 26
Proposed ALICE EMCAL
EM Sampling Calorimeter (STAR Design)
Pb-scintillator linear response -0.7 < < 0.7 /3 < <
Energy resolution ~15%/√E
8-12 Feb. 2007 Yves Schutz @ ICPAQGP5 27
Alice uses ~all known techniques!
0 1 2 3 4 5 p (GeV/c)
1 10 100 p (GeV/c)
TRD e / PHOS /0
TPC + ITS (dE/dx)
/K
/K
/K
K/p
K/p
K/p
e /
e /
HMPID (RICH)
TOF
Aerogel Cherenkov 10 GeV/c
ALICE PID
EMCAL
8-12 Feb. 2007 Yves Schutz @ ICPAQGP5 28
Jet Phase Space
0 1 2 10 100
pt (GeV/c)
Bulk properties
Hard processesModified by the medium
T=QCD Qs
ALICE Tracking & PID
Jets from Correlations and Leading Particles
Reconstructed Jets
Mini-jets 100/event 1/event 100K/year
CMS&ATLAScalorimetry
“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. 2007 Yves Schutz @ ICPAQGP5 29
LHC
8-12 Feb. 2007 Yves Schutz @ ICPAQGP5 30
LHC
8-12 Feb. 2007 Yves Schutz @ ICPAQGP5 31
ATLAS
8-12 Feb. 2007 Yves Schutz @ ICPAQGP5 32
CMS
8-12 Feb. 2007 Yves Schutz @ ICPAQGP5 33
ALICE
8-12 Feb. 2007 Yves Schutz @ ICPAQGP5 34
More at ICPAQGP6
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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
PbPb = 8barn; LPbPb 1027cm-2s-1; t0=04/2007