john harris (yale) gordon research conference on nuclear physics 2009 the relativistic heavy ion...
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John Harris (Yale) Gordon Research Conference on Nuclear Physics 2009
The Relativistic Heavy Ion Frontier at the LHC
The Strong Coupling Constant s
heavy quark-antiquark coupling at finite T from lattice QCD O.Kaczmarek, hep-lat/0503017
Constituents - Hadrons, dressed quarks, quasi-hadrons, resonances?
Coupling strength variesinvestigates (de-)confinement, hadronization, & intermediate objects.
low Q2high Q2
D. Gross
H.D. Politzer
F. Wilczek
QCD Asymptotic Freedom (1973)
Nobel Prize 2005
“Before [QCD] we could not go back further than 200,000 years after the Big Bang. Today…since QCD simplifies at high energy, we can extrapolate to very early times when nucleons melted…to form a quark-gluon plasma.” David Gross, Nobel Lecture (RMP 05)
John Harris (Yale) Gordon Research Conference on Nuclear Physics 2009
Behavior of QCD at High Temperature
few d.o.f.confined
many d.o.f.deconfined
F. Karsch, et al.Nucl. Phys. B605 (2001) 579
TC ~ 175 8 MeV C ~ 0.3 - 1 GeV/fm3
/T4 ~ # degrees of freedom
24
30T
John Harris (Yale) Gordon Research Conference on Nuclear Physics 2009
Phase Diagram of QCD MatterT
emp
erat
ure
net baryon density
Early universe
nucleinucleon gas
hadron gascolor
superconductor
quark-gluon plasma
Tc
~ 1
70
Me
V
0
Critical point ?
vacuum
CFLNeutron stars
see: Alford, Rajagopal, Reddy, Wilczek Phys. Rev. D64 (2001) 074017L
HC
RHIC
John Harris (Yale) Gordon Research Conference on Nuclear Physics 2009
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) Gordon Research Conference on Nuclear Physics 2009
Simple Expectations – Heavy Ions at RHIC 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
> 10 longer-lived
RHICLHC
John Harris (Yale) Gordon Research Conference on Nuclear Physics 2009
RHIC and new Large Hadron Collider (LHC) at CERN in Geneva:
Cover 3 decades of energy (sNN ~ 20 GeV – 5.5 TeV)
To discover the properties of hot QCD (at T ~ 150 – 600 MeV)
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) Gordon Research Conference on Nuclear Physics 2009
Why Heavy Ions at the LHC?•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 statesJohn Harris (Yale) Gordon Research Conference on Nuclear Physics 2009
LHC Heavy Ion Program
LHC Heavy Ion Data-taking Pb + Pb at sNN = 5.5 TeV
(1 month per year)
• LHC Collider Detectors- ATLAS- CMS- ALICE
John Harris (Yale) Gordon Research Conference on Nuclear Physics 2009
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: Brookhaven National Lab Columbia University Iowa State University Stony Brook University
John Harris (Yale) Gordon Research Conference on Nuclear Physics 2009
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: 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) Gordon Research Conference on Nuclear Physics 2009
CMS Heavy Ion Program
John Harris (Yale) Gordon Research Conference on Nuclear Physics 2009
ALICE – Heavy Ion Experiment
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 UniversityAffiliated members: Kent State University University of Texas – Austin
John Harris (Yale) Gordon Research Conference on Nuclear Physics 2009
The ALICE Experiment
John Harris (Yale) Gordon Research Conference on Nuclear Physics 2009
First LHC Beam in ALICE
• ALICE ready for LHC collisions.
• First LHC proton beams circulated on
September 10th , 2008.
• 450 GeV/c proton + pixel interaction
John Harris (Yale) Gordon Research Conference on Nuclear Physics 2009
Heavy Ion Physics at the LHC – Day 1LHC 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?
Particle Multiplicities
LHC
John Harris (Yale) Gordon Research Conference on Nuclear Physics 2009
Heavy Ion Physics at the LHC – Day 2LHC 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) Gordon Research Conference on Nuclear Physics 2009
Probing Hot QCD Matter with “Hard-Probes”
hadrons
leading particle
hadrons
leading particle
parton energy loss: modification of jets and leading particles & jet-correlations
John Harris (Yale) Gordon Research Conference on Nuclear Physics 2009
Initial Hard Parton Scattering gluon-gluon gluon-quark quark-quark
Hard ProbesLarge “pT” partonsHeavy quark – anti-quark
Initial Hard Parton Scattering gluon-gluon gluon-quark quark-quark
Hard ProbesLarge “pT” partonsHeavy quark – anti-quark
John Harris (Yale) Gordon Research Conference on Nuclear Physics 2009
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
Hard Probes with LHC Heavy Ions
, s1/2= 17 GeV
, s1/2= 200 GeV
, s1/2= 5500 GeV
bb (LHC ) ~ 100 bb (RHIC)
cc (LHC) ~ 10 cc (RHIC)
Rat
e
Hard Probes I – Jets and Parton Energy Loss
John Harris (Yale) Gordon Research Conference on Nuclear Physics 2009
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?
q = 2 / ^
q ~
John Harris (Yale) Gordon Research Conference on Nuclear Physics 2009
Jet-finding - Learning from 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) Gordon Research Conference on Nuclear Physics 2009
Jet Quenching in CMS at the LHC
Jet spectra up to ET ~ 500 GeV (Pb-Pb, 0.5 nb-1, HLT(triggered)
Courtesy: CMS
John Harris (Yale) Gordon Research Conference on Nuclear Physics 2009
Hard Probes II - Heavy Quark Production
John Harris (Yale) Gordon Research Conference on Nuclear Physics 2009
Heavy Flavor RAA at RHIC & LHC!
RHIC: Large uncertainties - electrons only - ratio of c to b is uncertain - awaits upgraded vertex detectors
Wicks & Gyulassy, Last Call for LHC Predictions
RHIC LHC
Heavy quark electrons at RHIC D & B mesons at LHC
LHC: measure D and B mesons - Precise measurements of RAA
to large pT
John Harris (Yale) Gordon Research Conference on Nuclear Physics 2009
Charm and Beauty E-Loss (e.g. ALICE)Heavy Quarks (mass/color dependence of parton energy-loss)
Displaced vertices (Do K- +) from trackingElectrons from Transition Radiation Detectors, EM Cal’s….
1 nominal year: 107 central Pb-Pb events, 109 pp eventserrors: statistical (bars) and systematic (bands)
Sensitive to color charge
Sensitive to mass dep.E-loss calc.: Armesto, Dainese, Salgado, Wiedemann
John Harris (Yale) Gordon Research Conference on Nuclear Physics 2009
Example – B-jet Physics in ALICE
John Harris (Yale) Gordon Research Conference on Nuclear Physics 2009
Quark vs gluon E-loss in medium
B-jets - pure sample of quark jets
Quarkonia
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) Gordon Research Conference on Nuclear Physics 2009
Heavy 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/, , ’ (abundant), ’’(fewer), ’ (more difficult)
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/, , ’ (abundant), ’’(fewer), ’ (more 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: ’’, ’,
Example – Quarkonia in CMS at the LHC
John Harris (Yale) Gordon Research Conference on Nuclear Physics 2009
Courtesy: CMS
At LHC:
Is the QCD phase diagram feature-less at 1 – 4 Tc?
What happens as we go up in T (e.g. coupling)?
Are there new phenomena?
What’s the range of theoretical validity (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?)
Developments in theory (lattice, hydro, parton E-loss, string theory…)
“the next frontier!”
The Quark-Gluon Plasma at RHIC & LHC –Today’s Perspective
John Harris (Yale) Gordon Research Conference on Nuclear Physics 2009
The End
John Harris (Yale) Gordon Research Conference on Nuclear Physics 2009
ALICE Collaboration
~ 1000 Members
(63% - CERN States)
~ 30 Countries
~ 100 Institutes
~ 150 M CHF capital
(+ ‘free’ magnet)
0
200
400
600
800
1000
1200
1990 1992 1994 1996 1998 2000 2002 2004
ALICE Collaboration statistics
LoI
MoU
TP
TRD
John Harris (Yale) Gordon Research Conference on Nuclear Physics 2009
Hard Probe Capabilities of ALICE with EMCal
EMCal improves detector capabilities:- Fast trigger ~10 -100 enhancement of jets
- Improves jet reconstruction (plus TPC)
- Good discrimination
increases coverage
- Good electron/hadron discrimination
EMCal extends the physics of 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) Gordon Research Conference on Nuclear Physics 2009
Example: High PT Suppression – RHIC and LHC
John Harris (Yale) Tamura Symposium, U. T. – Austin, 20 – 22 Nov. 2008
Courtesy: B. Wyslouch and CMS
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
Search for leading particle: - leading ~ 180º
e.g. Eleading > 0.1 E
John Harris (Yale) Gordon Research Conference on Nuclear Physics 2009
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) Gordon Research Conference on Nuclear Physics 2009
Example of Anticipated Jet Measurements
dN /d = 2700 Top 0.5% σAA
Reconstructed spectra not corrected for efficiency or energy resolution.
Courtesy: ATLAS
John Harris (Yale) Gordon Research Conference on Nuclear Physics 2009
- 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
A Real Test of “Theories” in the Future from Heavy Flavors at RHIC & LHC?
W. Horowitz, M. Gyulassy, arXiv:0804.4330v1
John Harris (Yale) Gordon Research Conference on Nuclear Physics 2009
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
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) Gordon Research Conference on Nuclear Physics 2009
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
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
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 53
-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