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