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

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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

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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!

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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

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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!

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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)

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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

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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

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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

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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/

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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

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“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

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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

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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

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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

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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

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Backup

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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

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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

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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

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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

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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

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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

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Annual yields at RHIC II & LHC from Tony Frawley RHIC Users mtg.

at LHC: (10-50) x ~10% of L 25% running time

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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!

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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

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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!