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Axel Drees, Stony Brook UniversityRutgers NJ, January 12 2006
High T QCD at RHIC: Hard Probes
Fundamental open questions for high T QCDNature of matter created at RHICCritical PointHadronizationRapid thermalization
Experimental quest for answersStatus of key experimental probes limitations of progress and solutions with upgrades of RHIC
Ongoing and planed improvements to RHICTime line, detector and accelerator upgrades (RHIC II)
Summary
Axel Drees
Exploring the Phase Diagram of QCD Quark Matter: Many new phases of matter
Asymptotically free quarks & gluonsStrongly coupled plasmaSuperconductors, CFL ….
Experimental access to “high” T and moderate region: heavy ion collisions
Pioneered at AGS and SPSOngoing program at RHIC
Quark Matter
Hadron Resonance Gas
Nuclear Matter
sQGP
B
T
TC~170 MeV
940 MeV 1200-1700 MeVbaryon chemical potential
tem
per
atu
re
Mostly uncharted territory
Overwhelming evidence:Strongly coupled quark matter
produced at RHIC
Study high T and QCD in the Laboratory
Axel Drees
III. Jet Quenching
dNg/dy ~ 1100
I. Transverse Energy
central 2%
PHENIX130 GeV
Bjorken estimate: ~ 0.3 fm
02j
TB
1 1 d
c dy
E
R
Quark Matter Produced at RHIC
~ 10-20 GeV/fm3
Initial conditions:
therm ~ 0.6 -1.0 fm/c
~15-25 GeV/fm3
II. Hydrodynamics
Huovinen et al
V2
Pt GeV/c
Heavy ion collisions provide the laboratory to study high T QCD!
Axel Drees
Fundamental Questions
Is the quark-gluon plasma the most perfect liquid? If not, what are its quasi particles?
Hard penetrating probes with highest possible luminosity at top RHIC energiesExcitation function and flavor dependence of collective behavior
Is there a critical point in the QCD phase diagram and where is it located?
Low energy scan of hadron productionLow energy scan of dilepton production with highest possible luminosity
How does the deconfined matter transform into hadrons?Flavor dependence of spectra and collective flow
How are colliding nuclei converted into thermal quark-gluon plasma so rapidly?
Hard probes at forward rapidity
Question formulated at QCD workshop, Washington DC 12/2006
and our experimental approach at RHIC
Axel Drees
Fundamental Question (I)
Is the quark-gluon plasma the most perfect liquid? If not, what are its quasi particles?
What are the properties of new state of matter?Temperature, density, viscosity, speed of sound, diffusion
coefficient, transport coefficients ….
If it’s a fluid: What is the nature a relativistic quantum fluid?If not: What is it and what are the relevant degrees of freedom?
Key are precision measurements with hard probes and of collective behavior currently not accessible at RHIC
RHIC upgrades: improved detectors and increased luminosity
Axel Drees
Key Experimental Probes of Quark Matter
Rutherford experiment atom discovery of nucleus
SLAC electron scattering e proton discovery of quarks
penetrating beam(jets or heavy particles)
absorption or scattering pattern
QGP
Nature provides penetrating beams or “hard probes”and the QGP in A-A collisions
Penetrating beams created by parton scattering before QGP is formed High transverse momentum particles jetsHeavy particles open and hidden charm or bottom Calibrated probes calculable in pQCD
Probe QGP created in A-A collisions as transient state after ~ 1 fm
Axel Drees
Hard Probes: Light quark/gluon jetsStatus
Calibrated probeStrong medium effect
Jet quenchingReaction of medium to
probe (Mach cones, recombination, etc. )
Matter is very opaqueSignificant surface biasLimited sensitivity to
energy loss mechanism
AAAA
coll pp
YieldR
N Yield
Which observables are sensitive to details of energy loss mechanism?What is the energy loss mechanism? Do we understand relation between energy loss and energy density?What phenomena relate to reaction of media to probe?
Answers will come from jet tomography (-jet): single, two and three particle analysis
Progress limited by:statistics (pT reach) increase luminosity and/or rate capabilitykinematic coverage increase acceptance & add pid
hydro
vacuum fragmentationreaction of medium
0-12%
STAR
trigger 2.5-4 GeV, partner 1.0-2.5 GeV
Axel Drees
Jet Tomography at RHIC II
W.Vogelsang NLO RHIC II L= 20nb-1
LHC: 1 month run
or
trigger
<z> ~ 0.1 for particles in recoil jet
with RHIC II
without RHIC II
RHIC II luminosities will give jets up to 50 GeV separation of medium reaction and energy loss sufficient statistics for 3 particle correlations pT > 5 GeV 2-3 particle correlations with identified particles
Medium reactinghadron < 5 GeV
Axel Drees
Hard Probes: Open Heavy FlavorStatus
Calibrated probe?pQCD under predicts cross
section by factor 2-5 Factor 2 experimental
differences in pp must be resolved
Charm follows binary scaling
Strong medium effectsSignificant charm suppressionSignificant charm v2Upper bound on viscosity ? Little room for bottom
production
Limited agreement with energy loss calculations
Electrons from c/b hadron decays
What is the energy loss mechanism? Where are the B-mesons?
Answers expected from direct charm/beauty measurements
Progress limited by: no b-c separation decay vertex with silicon vertex detectors
statistics (BJ/) increase luminosity and/or rate capability
Axel Drees
m cGeV m
D0 1865 125 D± 1869 317
B0 5279 464 B± 5279 496
Direct Observation of Charm and BeautyDetection options with vertex detectors:• Beauty and low pT charm through displaced e and/or • Beauty via displaced J/• High pT charm through D K
e
D Au
AuD
X
J/
B
X
K
ee
RHIC II increases statistics by factor >10
PHENIX VXT ~2 nb-1
Axel Drees
Hard Probes: QuarkoniumStatus
J/ production is suppressed Similar at RHIC and
SPSConsistent with
consecutive melting of and ’
Consistent with melting J/ followed by regeneration
Recent Lattice QCD developmentsQuarkonium states do
not melt at TC Is the J/ screened or not?Can we really extract screening length from data?
Answers require “quarkconium” spectroscopy
Progress limited by:statistics (’, ) increase luminosity and/or rate
capability
RAA
J/
Axel Drees
Signal
|| or PHENIX
<0.35, 1.2-2.4
STAR
<1
ALICE
<0.9, 2.5-4
CMS
<2.4
ATLAS
<2.4
J/ → or ee
440,000 220,000 390,000 40,000 8K-100K
’→ or ee 8000 4000 7,000 700 140-1800
c → or ee
120,000 * - - - -
→ or ee 1400 11000** 6000 8000 15,000
B → J/ → ee)
8000 2500 12,900 - -
D → K 8000**** 30,000*** 8,000 - -
LHC relative to RHIC Luminosity ~ 10%Running time ~ 25%Cross section ~ 10-50x
~ similar yields!
Compiled by T.Frawley
* large background** states maybe not resolved*** min. bias trigger**** pt > 3 GeV
Quarkonium and Open Heavy Flavor
Will be statistics limited at RHIC II (and LHC!)
RHIC II 20 nb-1 LHC on month
Axel Drees
Fundamental Questions (III)
How does the deconfined matter transform into hadrons?
Status:Elliptic flow (v2)
v2 of mesons and baryons scale with constituent quark number
Evidence for deconfined quarks
Hadronisation via recombination of constituent quarks in QGP
Progress from s and flavor dependence of collective flow
Limited by: flavor detection capabilities s, c, b mesons and baryons
vertex detectors and extended particle ID
STAR AuAu 62.4 GeV
with TOF barrel
Axel Drees
How are colliding nuclei converted into thermal quark-gluon plasma so rapidly? Initial state and entropy generation.What is the low x cold nuclear matter phase?
eRHIC
FAIR
RHIC
LHC
Fundamental Questions (IIII)
Answers at RHIC from hard probes at forward rapidity, ultimately EIC needed
Progress at RHIC limited by: detection capabilities forward detector upgrades
Status:Intriguing hints for CGC (color glass condensate) at RHIC
Bulk particle multiplicities “mono jets” at forward rapidity
STAR
Axel Drees
Long Term Timeline of Heavy Ion Facilities2006 2012
RHIC
2009
LHC
FAIRPhase III: Heavy ion physics
PHENIX & STAR upgrades
electron cooling “RHIC II”
electron injector/ring “e RHIC”
2015
Vertex tracking, large acceptance, rate capabilities
Axel Drees
RHIC Upgrades
STARforward meson spectrometerDAQ & TPC electronics
full ToF barrelheavy flavor trackerbarrel silicon tracker
forward tracker
Completed, on going, proposal submitted, in preparation
PHENIX
hadron blind detectormuon Trigger
silicon vertex barrel (VTX)forward silicon
forward EM calorimeter
On going effort with projects in different stages
Accelerator upgradesDetector upgrades
EBIS ion source
Electron cooling (x10 luminosity) by 2008 at 200 GeV extra x10 Au+Au ~40 KHz event rate
Electron cooling at <20 GeVAdditional factor of 10Au+Au 20 GeV ~15 KHz event rateAu+Au 2 GeV ~150 Hz event rate
Axel Drees
Fundamental Questions
Is the quark-gluon plasma the most perfect liquid? If not, what are its quasi particles?
Hard penetrating probes with highest possible luminosity at top RHIC energiesExcitation function and flavor dependence of collective behavior
Is there a critical point in the QCD phase diagram and where is it located?
Low energy scan of hadron productionLow energy scan of dilepton production with highest possible luminosity
How does the deconfined matter transform into hadrons?Flavor dependence of spectra and collective flow
How are colliding nuclei converted into thermal quark-gluon plasma so rapidly?
Hard probes at forward rapidity
Question formulated at QCD workshop, Washington DC 12/2006
and our experimental approach at RHIC
Key measurements and many precision measurements unavailable at RHIC
today!
Progress requires:
Improved detectors (STAR and PHENIX)vertex tracking, large acceptance, rate
capability
Luminosity upgrade (RHIC II)electron cooling for all energies
Improved theoretical guidancephenomenological tools (e.g. 3-D viscous
hydro) lattice QCD (e.g. finite density)new approaches (e.g. gauge/gravity
correspondence)
Axel Drees
Backup
Axel Drees
Which Measurements are Unique at RHIC?
General comparison to LHCLHC and RHIC (and FAIR) are complementaryThey address different regimes (CGC vs sQGP vs hadronic matter)Experimental issues: “Signals” at RHIC overwhelmed by “backgrounds” at LHC
Measurement specific (compared to LHC)Jet tomography: measurements and capabilities complementary
RHIC: large calorimeter and tracking coverage with PID in few GeV rangeExtended pT range at LHC
Charm measurements: favorable at RHICAbundant thermal production of charm at LHC, no longer a penetrating
probeLarge contribution from jet fragmentation and bottom decayCharm is a “light quark” at LHC
Bottom may assume role of charm at LHC
Quarkonium spectroscopy: J/, ’ , c easier to interpreter at RHICLarge background from bottom decays and thermal production at LHCRates about equal; LHC 10-50 , 10% luminosity, 25% running timer
Low mass dileptons: challenging at LHCHuge irreducible background from charm production at LHC
Axel Drees
Beyond PHENIX and STAR upgrades?Do we need (a) new heavy ion experiment(s) at RHIC?
Likely, if it makes sense to continue program beyond 2020Aged mostly 20 year old detectorsCapabilities and room for upgrades exhaustedDelivered luminosity leaves room for improvement
Nature of new experiments unclear at this point!Specialized experiments or 4 multipurpose detector ???
Key to future planning:First results from RHIC upgrades
Detailed jet tomography, jet-jet and -jetHeavy flavor (c- and b-production) Quarkonium measurments (J/, ’ , )Electromagnetic radiation (e+epair continuum)Status of low energy program
Tests of models that describe RHIC data at LHCValidity of saturation pictureDoes ideal hydrodynamics really work Scaling of parton energy lossColor screening and recombination
New insights and short comings of RHIC detectors will guide planning on time scale 2010-12
Axel Drees
Key probe: electromagnetic radiation:No strong final state interactionCarry information from time of emission to detectors and dileptons sensitive to highest temperature of plasma
Dileptons sensitive to medium modifications of mesons
(only known potential handle on chiral symmetry restoration!)
e+
e-
Fundamental Questions (I & II)
StatusFirst indication of thermal radiation at RHICStrong modification of meson properties
Precision data from SPS, emerging data from RHIC
Theoretical link to chiral symmetry restoration remains unclear
Can we measure the initial temperature?Is there a quantitative link from dileptons to chiral symmetry resoration?
NA60
Answers will come with more precision data upgrades and low energy running
Axel Drees
RHIC II Accelerator upgrades
EBIS ion source~30% higher with U+U
Luminosity increase at 200 GeVx4 above design achieved by 2008 Electron cooling at 200 GeV extra x10 Au+Au ~40 KHz event rate
Electron cooling at <20GeVAdditional factor of 10Au+Au 20 GeV ~15 KHz event rateAu+Au 2 GeV ~150 Hz event rate
Exp
ecte
d w
hole
vert
ex m
inb
ias e
ven
t ra
te [
Hz]
T. Roser, T. SatogataT. Roser, T. Satogata
RHIC Heavy Ion Collisions
Increase by additionalfactor 10with electron cooling
Axel Drees
Signal
|| or PHENIX<0.35, 1.2-2.4
STAR
<1
ALICE<0.9, 2.5-4
CMS<2.4
ATLAS<2.4
J/ → or ee 440,000 220,000 390,000 40,000 8K-100K
’→ or ee 8000 4000 7,000 700 140-1800
c → or ee 120,000 * - - - -
→ or ee 1400 11000** 6000 8000 15,000
B → J/ → ee)
8000 2500 12,900 - -
D → K 8000**** 30,000*** 8,000 - -
LHC relative to RHIC Luminosity ~ 10%Running time ~ 25%Cross section ~ 10-50x
~ similar yields!
Potential improvements with dedicated experiment4 acceptance J/’ 10x
2-10xbackground rejection c ????
Note: for B, D increase by factor 10 extends pT by ~3-4 GeV
Compiled by T.Frawley
* large background** states maybe not resolved*** min. bias trigger**** pt > 3 GeV
Quarkonium and Open Heavy Flavor
Will be statistics limited at RHIC II (and LHC!)
Axel Drees
NCCNCC
MP
C
MP
C
VTX & FVTX
-3 -2 -1 0 1 2 3 rapidity
cove
rage
2
HBD
EM
CA
LE
MC
AL
(i) 0 and direct with combination of all electromagnetic calorimeters(ii) heavy flavor with precision vertex tracking with silicon detectors
combine (i)&(ii) for jet tomography with -jet
(iii) low mass dilepton measurments with HBD + PHENIX central arms
Future PHENIX Acceptance for Hard Probes
Axel Drees
RHIC Upgrades OverviewUpgrades High T QCD Spin Low x
e+e- heavy jet quarkonia W G/G
flavortomograph
y
PHENIX
hadron blind detector (HBD) X
Vertex tracker (VTX and FVTX) X X O O O O
trigger O X
forward calorimeter (NCC) O X O X
STAR
time of flight (TOF) O X O
Heavy flavor tracker (HFT) X O O
tracking upgrade O O X O
Forward calorimeter (FMS) O X
DAQ O X X O O O
RHIC luminosity O O X X O O O
X upgrade critical for successO upgrade significantly enhancements program
Axel Drees
Comparison of Heavy Ion Facilities
FAIR TC
RHIC 2 TC
LHC 3-4 TC
Initial conditions
Complementary programs with large overlap:High T: LHC adds new high energy probes
test prediction based on RHIC dataHigh : FAIR adds probes with ultra low cross section
RHIC is unique and at “sweet spot”
FAIR: cold but dense baryon
rich matterfixed target p to UsNN ~ 1-8 GeV U+UIntensity ~ 2 109/s ~10 MHz ~ 20 weeks/year
RHIC: dense quark matter to
hot quark matter Collider p+p, d+A and A+AsNN ~ 5 – 200 GeV U+ULuminosity ~ 8 1027 /cm2s ~50 kHz ~ 15 weeks/year
LHC: hot quark matterCollider p+p and A+AEnergy ~ 5500 GeV Pb+PbLuminosity ~ 1027 /cm2s ~5 kHz~ 4 week/year
Axel Drees
Midterm Strategy for RHIC Facility
Detectors:Particle identification reaction of medium to eloss, recombination Displaced vertex detection open charm and bottomIncreased rate and acceptance Jet tomography, quarkonium, heavy flavorsDalitz rejection e+epair continuumForward detectors low x, CGC
Accelerator:EBIS Systems up to U+UElectron cooling increased luminosity
Key measurements require upgrades of detectors and/or RHIC luminosity
Axel Drees
Dalitz/conversion rejection (HBD)Precision vertex tracking (VTX)
PID (k,,p) to 10 GeV (Aerogel/TOF)
High rate trigger ( trigger)Precision vertex tracking (FVTX)
Electron and photon measurementsMuon arm acceptance (NCC)Very forward (MPC)
PHENIX Detector Upgrades at a GlanceCentral arms:
Electron and Photon measurementsElectromagnetic calorimeterPrecision momentum determination
Hadron identification
Muon arms:Muon
IdentificationMomentum determination
Axel Drees
Full Barrel Time-of-Flight system
DAQ and TPC-FEE upgrade
Forward Meson Spectrometer
Integrated Tracking Upgrade
HFT pixel detector
Barrel silicon tracker
Forward silicon tracker
Forward triple-GEM EEMC tracker
STAR Upgrades
Axel Drees
Comments on High pT Capabilities
LHC Orders of magnitude larger cross sections ~3 times larger pT range
RHIC with current detectors (+ upgrades)Sufficient pT reachSufficient PID for associated particlesWhat is needed is integrated luminosity!
Region of interest for associated particles up to pT ~ 5 GeV