axel drees, university stony brook washington dc, december 15 2006 high t and qcd in the bnl qcd...
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Axel Drees, University Stony BrookWashington DC, December 15 2006
High T and QCD in the BNL QCD Lab Era
IntroductionQCD phase diagramStatus of heavy ion physicsHeavy ion facilities
Fundamental questions
Key experimental probes: hard probes
Jet quenching, heavy flavor, quarkconium
Electro-magnetic radiationPhotons and lepton pairs
Summary of burning issues
CommentsLow energy running at RHICRHIC vers LHCBeyond PHENIX and STAR
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 SPS and AGSOngoing 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
PHENIXHuovinen et al
V2
Pt GeV/c
Heavy ion collisions provide the laboratory to study high T QCD!
Axel Drees
Long Term Timeline of Heavy Ion Facilities2006 2012
RHIC
2009
LHC
FAIRPhase III: Heavy ion physics
QCD Laboratory at BNL
PHENIX & STAR upgrades
electron cooling “RHIC II”
electron injector/ring “e RHIC”
2015
Vertex tracking, large acceptance, rate capabilities
Axel Drees
Quark Matter
Hadron Resonance Gas
Nuclear Matter
SIS
B
T
TC~170 MeV
940 MeV 1200-1700 MeVbaryon chemical potential
tem
per
atu
re
thermal freeze out
chemical freeze out
RHIC/BNL
LHC/CERN
FAIR/GSI
Different accelerators probe different regions of the phase diagram!
Exploring the QCD phase diagram:Is there asymptotically free quark matter? What is the nature of a relativistic quantum fluid? What are the relevant degrees of freedom? Is there a critical point?
Physics at the phase transition:Why are quarks confined in hadrons?Why are hadrons massive and what is the relation to chiral symmetry breaking?
Fundamental Questionswhich may find experimental answers using heavy ion collisions!
Axel Drees
Initial state and entropy generation:How and why does matter thermalize so fast?What is the low x cold nuclear matter phase?
Related to time evolution of the collision!
eRHIC
FAIR
RHIC
LHC
Fundamental Questions (II)
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?
Answers will come from jet tomography (-jet) RHIC upgrades & LHC
0-12%
STAR
Axel Drees
Hard Probes: Open Heavy Flavor
StatusCalibrated 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 from direct charm/beautymeasurements RHIC upgrades
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 RHIC upgrades and LHC(?)
RAA
J/
Axel Drees
Electromagnetic radiation:No strong final state interactionCarry information from time of emission to detectors
and dileptons sensitive to highest temperature of plasmaDileptons sensitive to medium modifications of
mesons (only known potential handle on chiral symmetry
restoration!)
e+
e-
Key Experimental Probes of Quark Matter (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
“Burning” Open Issues:
Jets and heavy quarksWhich observables are sensitive to details of energy loss mechanism?How important is collisional energy loss?Do we understand relation between energy loss and energy density?Where are the B-mesons?Which probes are sensitive to the medium and what do they tell us?
QuarkoniumIs the J/ screened or not?Can we really extract screening length from data?
Electromagnetic radiationCan we measure the initial temperature?Is there a quantitative link from dileptons to chiral symmetry restoration?
Answers will come from QCD laboratory and LHC
Axel Drees
Low Energy Running at RHICPhysics goals:
Search for critical point bulk hadron production and fluctuations
Requires moderate luminosity can maybe be done in next years
Chiral symmetry restoration dilepton production
Requires highest possible luminosity, i.e. electron cooling
Luminosity estimate with electron coolingAssume 4 weeks of physics each, 25% recorded luminosity and sufficient triggers
20 GeV 109 events
2 GeV 107 events
CERES best run ~ 4x107 eventsNA60 In+In ~ 1010 sampled events
Exp
ecte
d w
hole
vert
ex m
inb
ias e
ven
t ra
te [
Hz]
T. Roser, T. SatogataT. Roser, T. SatogataRHIC Heavy Ion Collisions
Increase by factor 100with electron cooling
Very strong low energy program possible at RHIC
SPSFAIR
RHIC
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)Charm measurements: favorable at RHIC
Charm is a “light quark” at LHC, no longer a penetrating probeAbundant thermal production of charmLarge contribution from jet fragmentation and bottom decay
Bottom may assume role of charm at LHC
Quarkonium spectroscopy: J/, ’ , c easier to interpreter at RHICRates about equal; LHC 10-50 , 10% luminosity, 25% running timerLarge background from bottom decays and thermal production at LHC
Precision Upsilon spectroscopy can only be done at LHC
Low mass dileptons: challenging at LHCHuge irreducible background from charm production at LHC
Jet tomography: measurements and capabilities complementaryRHIC: large calorimeter and tracking coverage with PID in few GeV range
Extended pT range 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
First quantitative tests at LHC of models that describe RHIC dataValidity of saturation pictureDoes ideal hydrodynamics really work Scaling of parton energy lossColor screening and recombination
New insights and short comings or failures of RHIC detectors will guide planning on time scale 2010-12
Axel Drees
Long Term Timeline of Heavy Ion Facilities2006 2012
RHIC
2009
LHC
FAIRPhase III: Heavy ion physics
QCD Laboratory at BNL
PHENIX & STAR upgrades
electron cooling “RHIC II”
electron injector/ring “e RHIC”
RHIC II and STAR/PHENIX upgrades provide enormous discovery potential 2010 to 2015 and
beyond
RHIC (and eRHIC) will remain prime facility for high T QCD beyond 2015
2015
Vertex tracking, large acceptance, rate capabilities
Axel Drees
Backup
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
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
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
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 X 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
Annual yields at RHIC II & LHC from Tony Frawley RHIC Users mtg.
at LHC: (10-50) x ~10% of L 25% running time
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
There is room for improvement if needed!
Quarkonium and Open Heavy Flavor
Will be statistics limited at RHIC and LHC!
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
Axel Drees
Estimates for -jet Tomography
Rapidly falling cross section with rapidity:
Assume ~ 1000 events required for statistical -jet correlation40x design luminosity
y max -pT (GeV)
0 231 212 153 8
Inclusive direct today
Detector + luminosityupgrades
Need to extend pT range not obvious!
Hadron pid ~ 4 GeV seems sufficient!