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John Harris (Yale) Tamura Symposium, U. T. – Austin, 20 – 22 Nov. 2008
The Relativistic Heavy Ion Frontier at the LHC
Tamura Symposium
The Quark-Gluon Plasma – Present View from RHIC
• Large > c (T > Tc) system – Sufficient for QGP formation – NOT hadrons
Particle ratios fit by thermal model T = 177 MeV ~ Tc (lattice QCD)
• Large volume of quarks & gluons (hydrodynamics) – NOT just q & g scattering
Large elliptic & radial flow large pressure gradients
Ultra-low shear viscosity “nearly-perfect” fluid flow
• Dynamics of quarks and gluons – QGP EoS, quark coalescence – NOT hadrons
Flow develops at quark level & depends upon constituent quark masses
• Strongly-coupled quarks and gluons – NOT Weakly-interacting QGP (as thought)
Large parton energy loss
John Harris (Yale) Tamura Symposium, U. T. – Austin, 20 – 22 Nov. 2008
Simple Expectations – Heavy Ion Interactions at LHC
QGP (fm/c)
(GeV/fm3)
T / Tc
√sNN (GeV) factor 28
2-4
5
1.9
200
RHIC
≤ 2
3
1.1
17
LHCSPS
5500
3.0 - 4.2 hotter
15-60 denser
> 10longer-lived
RHIC and LHC:
Cover 2 – 3 decades of energy (sNN ~ 20 GeV – 5.5 TeV)
To determine the properties of hot QCD at T ~ 150 – 600 MeV
John Harris (Yale) Tamura Symposium, U. T. – Austin, 20 – 22 Nov. 2008
Geometry of Heavy Ion Collisions at LHC
General Orientation
Hadron masses ~ 1 GeV
Hadron sizes ~ fm
LHC Heavy Ion Collisions
Ecm = 5.5 TeV per nn-pair
Total Ecm = 1.54 PeV
Lead nucleusdiameter ~ 14 fm
= 2,700 (Lorenz contracted)
~ (14 fm/c) / < 0.01 fm/c
John Harris (Yale) Tamura Symposium, U. T. – Austin, 20 – 22 Nov. 2008
Why Heavy Ions at the LHC?
John Harris (Yale) Tamura Symposium, U. T. – Austin, 20 – 22 Nov.
2008
•Expect different timescales, shorter interaction times, higher energy (T) !
Does system still equilibrate rapidly?
Thermal model still applies? T still ~ Tc (lattice QCD)?
Does it flow?
Elliptic Flow change? v2 still saturated? More or less v2?
Is the QGP still strongly- (or weakly-) coupled?
Liquid? More like a gas? No longer “nearly-perfect” fluid flow?
Impact on energy loss!!
• Understand parton energy loss! – What are the microscopic processes?
mass and flavor dependence?
use high pT jets & tag heavy quark jets
• Understand response of the medium!
Strongly interacting quarks and gluons away-side response?
use punch-through & associated jet
• Color screening of the medium!
Deconfinement? (compare LQCD), initial T, other effects J/ & Y states
LHC Heavy Ion Programs
Heavy Ion Data-taking
Pb + Pb at sNN = 5.5 TeV
John Harris (Yale) Tamura Symposium, U. T. – Austin, 20 – 22 Nov. 2008
ALICE – the Heavy Ion Experiment
ALICE is a versatile, heavy ion detector at the LHC
Overview:
Soft Probes – “ala RHIC” • Expansion dynamics different from RHIC• Soft physics measurements ala RHIC
+ extended PID• Day 1 physics +
Hard Probes – Jet Quenching• Jets, pi-zeros, leading particles to large pT
Hard Probes – Heavy Quarks• Displaced vertices (Do K- +) from TPC/ITS• Electrons in Transition Radiation Detector (TRD)
Hard Probes – Quarkonia• J/, , ’ (excellent), ’’(2-3 yrs), ’ ???
US Members: Cal. St. U. – San Luis Obispo Creighton University University of Houston Lawrence Berkeley Nat. Lab Lawrence Livermore Nat. Lab Oak Ridge National Lab Ohio State University Purdue University University of Tennessee Wayne State University Yale University
Affiliated US Member: University of Texas – Austin
John Harris (Yale) Tamura Symposium, U. T. – Austin, 20 – 22 Nov. 2008
The ALICE Experiment
John Harris (Yale) Tamura Symposium, U. T. – Austin, 20 – 22 Nov. 2008
CMS Heavy Ion Program
Overview:
CMS has a broad heavy ion physics program
- precision tracking < 2.5
- muon identification < 2.5
- high-res calorimetry < 5
- forward coverage
CMS expects to excel at
- photon-tagged jet measurements
(FF modifications)
- quarkonium measurements
US Members: University of California at Davis University of Illinois at Chicago University of Iowa University of Kansas Los Alamos National Laboratory University of Maryland MIT University of Minnesota Rice University Vanderbilt University
John Harris (Yale) Tamura Symposium, U. T. – Austin, 20 – 22 Nov. 2008
ATLAS Heavy Ion Program
Overview:
ATLAS has a broad heavy ion physics program- excels at jet and photon measurements
Jets- reconstruct jets in a large kinematical range
ET > 40 GeV and |η|<5- perform key fragmentation measurements- jet shape and FF modifications- multi-jet studies
Photons- isolate / measure photons in large range, ET > 10 GeV and |η|<2.5- unique calorimeter design allows additional rejection beyond isolation
US Members: Brookhaven National Lab Columbia University Iowa State University Stony Brook University
John Harris (Yale) Tamura Symposium, U. T. – Austin, 20 – 22 Nov. 2008
Heavy Ion Physics at the LHCLHC Heavy Ions –
• expectations based on pQCD predictions & RHIC results• a lesson from RHIC – guided by theory + versatility + “expect the unexpected”
Soft Physics (pT ≤ 2 GeV/c) with heavy ions at LHC – • smooth extrapolation from SPS RHIC LHC?
John Harris (Yale) Tamura Symposium, U. T. – Austin, 20 – 22 Nov. 2008
Particle Multiplicities
LHC
Heavy Ion Physics at the LHCLHC Heavy Ions –
• expectations based on pQCD predictions & RHIC results• a lesson from RHIC – guided by theory + versatility + “expect the unexpected”
Soft Physics (pT ≤ 2 GeV/c) with heavy ions at LHC – • smooth extrapolation from SPS RHIC LHC?• expansion dynamics different (initial state, flow, HBT, evolution of T, strange/charm/beauty)
x
z
y
John Harris (Yale) Tamura Symposium, U. T. – Austin, 20 – 22 Nov. 2008
Heavy Ion Physics at the LHCLHC Heavy Ions –
• expectations based on pQCD predictions & RHIC results• a lesson from RHIC – guided by theory + versatility + “expect the unexpected”
Soft Physics (pT ≤ 2 GeV/c) with heavy ions at LHC – • smooth extrapolation from SPS RHIC LHC?• expansion dynamics different (initial state, flow, HBT, evolution of T, strange/charm/beauty)
Elliptic Flow
John Harris (Yale) Tamura Symposium, U. T. – Austin, 20 – 22 Nov. 2008
Probing Hot QCD Matter with Hard Probes
hadrons
leading particle
hadrons
leading particle
parton energy loss: modification of jets and leading particles & jet-correlations
jets
jets
John Harris (Yale) Tamura Symposium, U. T. – Austin, 20 – 22 Nov. 2008
Parton Energy LossJet Quenching
(Parton energy-loss, parton density, medium response)What happens to the radiation?
Egluon > Equark, m=0 > Equark, m>0
How does E depend on type of parton?
• Jets, 0, leading particles to large pT
• Modification of fragmentation• Medium response to E deposition - dissipation on near- and away-side
EGluon radiation
Collision E-loss
How does parton lose energy?
John Harris (Yale) Tamura Symposium, U. T. – Austin, 20 – 22 Nov. 2008
q = 2 / ^
q ~
John Harris (Yale) Tamura Symposium, U. T. – Austin, 20 – 22 Nov. 2008
Significant increase in hard cross sections
(pT or mass > 2 GeV/c) at LHC – large pT /total~ 2% at SPS
50% at RHIC
98% at LHC• “real” jets, large pT processes
• abundance of heavy flavors• probe early times, calculable
bb (LHC ) ~ 100 bb (RHIC)
cc (LHC) ~ 10 cc (RHIC)
Rat
e
Hard Probes with LHC Heavy Ions
Example: High PT Suppression – RHIC and LHC
John Harris (Yale) Tamura Symposium, U. T. – Austin, 20 – 22 Nov. 2008
Courtesy: B. Wyslouch and CMS
Hard Probe Capabilities of ALICE
ALICE physics capabilities:- Fast trigger on jets (EMCal)
- Good discrimination (EMCal, PHOS)
- Electron/hadron disc. (TRD, EMCal)
Hard Probes statistics in ALICE:
104/year in minbias Pb+Pb:
inclusive jets: ET ~ 200 GeV
dijets: ET ~ 170 GeV
: pT ~ 75 GeV
inclusive : pT ~ 45 GeV
inclusive e: pT ~ 30 GeVThanks – Peter Jacobs
John Harris (Yale) Tamura Symposium, U. T. – Austin, 20 – 22 Nov. 2008
Jet-finding - Learning from the Tevatron & RHIC
p + p experience (CDF)
- most of energy within cone of
R = (2 + 2) < 0.3
p T /
cell
(GeV
/c)
200 GeV Au + Au central collision (STAR)
Ejet = 21 GeVAu + Au experience (STAR) - HI Background
Must suppress “soft” background:
- small jet cones R = 0.3-0.4
- pT cut: pT > 1 – 2 GeV/c
- EbyE out-of-cone background energy
John Harris (Yale) Tamura Symposium, U. T. – Austin, 20 – 22 Nov. 2008
Example of Anticipated Jet Measurements
dN /d = 2700 Top 0.5% σAA
Reconstructed spectra not corrected for efficiency or energy resolution.
Courtesy: B. Cole and ATLAS
Jet Quenching in CMS at the LHC
Jet spectra up to ET ~ 500 GeV (Pb-Pb, 0.5 nb-1, HLT(triggered)
Courtesy: C. Roland and CMS
Measuring the PbPb Fragmentation Function
Jet energy determination:
Rc=0.4 pT > 1 GeV/c
jet
More studies of background are needed & underway!
J. Putschke, ECT 2008
Charged particles for FF
Rc=0.7 pT > 0 GeV/c
John Harris (Yale) Tamura Symposium, U. T. – Austin, 20 – 22 Nov. 2008
Tagging Jets with Photons for Parton Energy
Reconstruct the jet : Particles around leading particle inside acone R = 0.3…
Search for & identify prompt photon with largest pT
John Harris (Yale) Tamura Symposium, U. T. – Austin, 20 – 22 Nov. 2008
Search for leading particle: - leading ~ 180º
e.g. Eleading > 0.1 E
- Jet Simulations in CMS at the LHC
Select away-side jet with (, jet) > 172o, ||< 2 and ET (jet) > 30 GeV
• ET (jet) cut reduces false rate to ~ 10% (Otherwise, no use of jet energy)
• Jet finding efficiency increases sharply from 30 - 100 GeV jet ET
Quenched Pb+Pb
Fal
se r
ate
frac
tio
n (
%)
Jet-
fin
din
g e
ffic
ien
cy
Courtesy: C. Roland and CMS
ET, > 70GeV
ET, > 100GeV
QuenchedUnquenched
QuenchedUnquenched
Fragmentation Functions in CMS
Courtesy: C. Roland and CMS
Heavy Flavor RAA at RHIC & LHC!
Uncertainties at RHIC (bands > ±0.1 ) - perturbative production of c and b jets - ratio of c to b jets is very uncertain.
Wicks & Gyulassy, Last Call for LHC Predictions
RHIC LHC
Heavy quark electrons at RHIC D & B mesons at LHC
LHC: - Different slopes of spectra
little effect on RAA results.
John Harris (Yale) Tamura Symposium, U. T. – Austin, 20 – 22 Nov. 2008
Charm and Beauty E-Loss in ALICE
Displaced vertices (Do K- +) from trackingElectrons from Transition Radiation Detectors, EM Cal’s….1 nominal year: 107 central Pb-Pb events, 109 pp events
errors: statistical (bars) and systematic (bands)
John Harris (Yale) Tamura Symposium, U. T. – Austin, 20 – 22 Nov. 2008
Sensitive to color charge
Sensitive to mass dep.E-loss calc.: Armesto, Dainese, Salgado, Wiedemann
B-jet Physics
Quark vs gluon E-loss in medium
B-jets - pure sample of quark jets
WHDG, arXiv:nucl-th/0512076
Measure B-jet Fragmentation Fctn
- harder fragmentation of b-quark
(higher <z> )
- Ejet measured more precisely
- Better measurement of FF
Fragmentation Function of b-quark
Wicks et al, nucl-th/0512076
John Harris (Yale) Tamura Symposium, U. T. – Austin, 20 – 22 Nov. 2008
ALICE B-jet Physics WHDG, arXiv:nucl-th/0512076
John Harris (Yale) Tamura Symposium, U. T. – Austin, 20 – 22 Nov. 2008
A Test of “Theories” in the Future from Heavy Flavors at RHIC & LHC?
W. Horowitz, M. Gyulassy, arXiv:0804.4330v1
John Harris (Yale) Tamura Symposium, U. T. – Austin, 20 – 22 Nov. 2008
QuarkoniaHeavy Quarks (mass/color dependence of parton energy-loss)
• Displaced vertices (Do K- +) from tracking• Electrons from Transition Radiation Detectors, EM Cal’s….
Quarkonia (initial temperature, Debye color screening, recombination)
• J/, , ’ (excellent), ’’(few yrs), ’ (difficult)
Color Screening
cc
Color screening of cc pairresults in J/ (cc) suppression!
Confined
Deconfined
r
V(r)
Bound state (e.g. J/)
Quarkonium dissociation when rDebye ~ 1/(sT) < rqq
John Harris (Yale) Tamura Symposium, U. T. – Austin, 20 – 22 Nov. 2008
John Harris (Yale) Tamura Symposium, U. T. – Austin, 20 – 22 Nov. 2008
QuarkoniaHeavy Quarks (mass/color dependence of parton energy-loss)
• Displaced vertices (Do K- +) from tracking• Electrons from Transition Radiation Detectors, EM Cal’s….
Quarkonia (initial temperature, Debye color screening, recombination)
• J/, , ’ (excellent), ’’(few yrs), ’ (difficult)
John Harris (Yale U.) US LHC User’s Meeting, 24 October 2008
T/TC 1/r [fm-1]
(1S)
J/(1S)
c(1P)
’(2S)
b’(2P)
’’(3S)
Karsch hep-lat/0502014v2
Measure melting order of cc: ’, c, J/bb: ’’, ’,
Quarkonia in CMS at the LHC
John Harris (Yale) Tamura Symposium, U. T. – Austin, 20 – 22 Nov. 2008
John Harris (Yale) Tamura Symposium, U. T. – Austin, 20 – 22 Nov. 2008
At LHC:
Is the QCD phase diagram feature-less at 1 – 4 Tc?
What happens as we go up in T (e.g. strongly-coupled)?
Are there new phenomena?
What’s the range of theoretical validities (non-pQCD, pQCD, strings)?
Measure/understand parton energy loss at the fundamental level
Establish flavor (gluon and quark mass) dependence
Use jets and/or photons to establish hard-scattered parton energy
Jet modifications - longitudinal & transverse “heating”
Medium response to jet-heating (near- and away-side)
Measure/use open charm and beauty decays (also as jet-tags)
cc and bb states (Ti, screening/suppression, enhancement?)
Direct Photon Radiation?
Developments in theory (lattice, hydro, parton E-loss, string theory…)
“the next frontier!”
Quark-Gluon Plasma at LHC – Today’s Perspective
The End
John Harris (Yale) Tamura Symposium, U. T. – Austin, 20 – 22 Nov. 2008
John Harris (Yale U.) BNL Physics Seminar, 2 September 2008
B.Hippolyte Hot Quarks 2008 - Estes Park
Material Budget
ALICE Ideal Reconstruction and identification low pT : lowest material
budget
Cumulative mid-rapidity material budget for ALICE, ATLAS and CMS
ALICE x/X0 (%) ATLAS x/X0 (%) CMS x/X0 (%)
Beam pipe 0.26 Beam pipe 0.45 Beam pipe 0.23
Pixels (7.6 cm) 2.73 Pixels (12 cm) 4.45 Pixels (10.2 cm) 7.23
ITS (50 cm) 7.43 SCT (52 cm) 14.45 TIB (50 cm) 22.23
TPC (2.6 m) 13 TRT (1.07 m) 32.45 TOB (1.1 m) 35.23
Calorimeter Comparisons
John Harris (Yale) LNF Spring School, Frascati 12 – 16 May 2008
ALICE Detectors & Acceptance
(charged particles)
µ arm
central barrel -0.9 < < 0.9• = 2 tracking, PID (TPC/ITS/ToF)• single arm RICH (HMPID)• single arm e.m. cal (PHOS)• jet calorimeter (proposed EMCal)
forward muon arm 2.4 < < 4• absorber, 3 T-m dipole magnet10 tracking + 4 trigger chambers
multiplicity detectors -5.4 < < 3• including photon counting in PMD
trigger & timing detectors• 6 Zero Degree Calorimeters• T0: ring of quartz window PMT's• V0: ring of scint. Paddles
John Harris (Yale) Winter Workshop on Nuclear Dynamics, South Padre Is. TX – 4/8/08
ALICE Jet Trigger Yields in an LHC Pb + Pb Year
Jet yield in 20 GeV bin
Large gains due to jet trigger
Large variation in statistical reach for different reference systems
Includes acceptance, efficiency, dead time, energy resolution
04/21/23
Particle Charmonia +- Charmonia e+e- Bottonia +- Bottonia e+e-
Bkg-subtr. mass plot
acc. -4 < < -2.5 || < 0.9 -4 < < -2.5 || < 0.9
M res. 65 MeV 35 MeV 90 MeV 90 MeVS /
(S+B)
(1 mo.) J/ 150, ’ 7 J/ 245
30, ’ 12,
’’ 8 21, ’ 8
Perf. , ’ , ’ , ’,’’ , ’, no ’’pt J/ 0-20 GeV J/ 0-10 GeV 0-8 GeV --
Quarkonia PerformancedNch/dy = 4000 in central Pb-Pb
Charm and Beauty E-Loss : RAA
D0 K
1 year at nominal luminosity(107 central Pb-Pb events, 109 pp events))
B e + X
D+ K
mC = 1.2 GeV
mC = 0
mb = 4.8 GeV
B eE-loss calc.: Armesto, Dainese, Salgado, Wiedemann
John Harris (Yale) Tamura Symposium, U. T. – Austin, 20 – 22 Nov. 2008
Sensitive to color chargeSensitive to mass
Andreas Morsch, Quark Matter 2008 44
-Jet Correlations
• Dominant processes in pp– g + q → + q (Compton)– q + q → + g (Annihilation)
• -jet correlations– E Ejet
– Opposite direction– Direct photons are not perturbed by
the medium
min max
IP
PHOS
EMCal
TPC
Direct are likely to be produced isolated. Two parameters define isolation:
Cone size RpT threshold, candidate isolated if:
No particle in cone with pT > pTthres
orpT sum in cone, pT < pT
thres
• Identification– Time of flight– Charged particle veto– Shower shape
John Harris (Yale) Gordon Research Conference, Nuc. Chem 2008
The Future of RHI‘s at the LHC:
Dedicated HI experiment - ALICE
Two pp experiments with HI programs:
ATLAS and CMS
John Harris (Yale) Tamura Symposium, U. T. – Austin, 20 – 22 Nov. 2008