john harris (yale) qcd lab workshop, bnl 17 – 22 july 2006 future perspective of heavy ion physics...

John Harris (Yale) QCD Lab Workshop, BNL 17 – 22 July 2006

Future Perspective of Heavy Ion Physics at the QCD Lab

Outline

• Where are we now (physics-wise) at RHIC?

• Where are we going (physics-wise)?

• What will it take to get there?

• What is the role of the QCD Lab in this field (with

RHIC & LHC)?


Where are we now (physics-wise) at RHIC?


After 5 Years of RHIC → Experimental Evidence for an sQGP

• After the completely unexpected RHIC v2 results on DAY 1 !

“perfect” fluid flow

came the STAR & PHENIX particle identified flow

appropriate dynamical approach QGP EoS,, quark coalescence

then the thermalization as seen in all particle ratios fit by thermal models

T = 177 MeV ~ Tc (lattice QCD)

• Next the remarkable STAR & PHENIX suppression of high pT hadrons

extreme gluon/energy densities (verifying initial PHENIX & STAR >> c )

observation of the spectacular disappearance of the away-side jet

large opacity

strongly-interacting QGP (sQGP)

• flow of heavy quarks and their suppression at high pT

similarity with light quarks defies theoretical predictions……


Where are we going (physics-wise)?


Where are we headed at RHIC?

PHENIX & STAR - “continue to establish presence & properties of sQGP”

Systematic study (vs.…) of soft observables

Electromagnetic Probes

Heavy Flavors

Hard Probes - jets

PHENIX & STAR: “will continue upgrading detector capabilities”

Increase triggering capabilities and DAQ rates

Expand apertures

Add new capabilities (micro-vertexing, low-mass di-leptons, high pT PID)

• Direct – thermal radiation, shadowing• Virtual (e+e-) - chiral restoration via low mass di-leptons

STAR HFT

PHENIX MVTX PHENIX HBD PHENIX Aerogel

STAR ToF

• Open charm, charmonium (, ’) spectroscopy• Open beauty, bottomonium (, ’, ’’) spectroscopy• Flavor-tagged jets

DeconfinementInitial T

• via leading particles• -jet, D-jet, B-jet, topology (jet energy)!

Parton energy lossProperties of QGPResponse of medium

Low physics require RHIC luminosity upgrade +


PHENIX & STAR - “continue to establish presence & properties of sQGP”

Systematic study (vs.…) of soft observables

Electromagnetic Probes

Heavy Flavors

Hard Probes - jets

PHENIX & STAR: “will continue upgrading detector capabilities”

Increase triggering capabilities and DAQ rates

Expand apertures

Add new capabilities (micro-vertexing, low-mass di-leptons, high pT PID)

Parton energy lossProperties of QGPResponse of medium

Low physics require RHIC luminosity upgrade +

Where are we headed at RHIC?

• Direct – thermal radiation, shadowing• Virtual (e+e-) - chiral restoration via low mass di-leptons

STAR HFT

PHENIX MVTX PHENIX HBD PHENIX Aerogel

STAR ToF

• Open charm, charmonium (, ’) spectroscopy• Open beauty, bottomonium (, ’, ’’) spectroscopy• Flavor-tagged jets

DeconfinementInitial T

• via leading particles• -jet, D-jet, B-jet, topology (jet energy)!

How far do the RHIC detector upgrades get us?


QCD Phase Diagram

300

350

400

250

200

150

100

50

0

T (

MeV

)

LHC initial state

RHIC initial states

Evolution - RHIC, LHC?• Differences

– Initial temperatures

– System lifetimes

– Evolution?

• Similarities

– Final stages of evolution

• Entire evolution different!

– Jet propagation

– Resulting energy

deposition

– Quarkonium melting


Open Questions at RHIC

• What are the degrees of freedom in the evolution at RHIC?

Can we determine the constituents as a function of energy density (or T)?

sQGP & its evolution• Initial T? ( HBT)

• Deconfinement Tc (Quarkonium melting)

• Constituents (partons, quasi-bound

states, pre-hadrons...)

• Parton density (jet tomography, flavor,

intra-, inter-jet correlations)

• Response to energy deposition

• Bulk properties

• Equation of State

• Chiral symmetry restoration?

LHC Shuryak


Future Systematic Studies of Soft Observables at

Establish Presence and Properties of the QGP!

When can we answer with confidence following questions…..


The sQGP Phase Transition

Is system thermalized? On what timescale ? Can we determine the

temperature? Nature of phase transition?

• Establish transport & diffusion coefficients

→ need microscopic transport

• Elliptic flow & RAA of D & B mesons → requires luminosity

Tri-critical point?

• Near bfreezout ~ Tc , √s ~ 25 GeV (not accessible at LHC)

• Vary √s search for enhancement in E-by-E fluctuations in <pT> and baryon

number → more run-time or luminosity.

What is the EoS ?

• Connection with thermodynamic properties of QGP on lattice

• PID elliptic flow & PID spectra

• Effective degrees of freedom versus multiplicity

→ deconfinement from lattice QCD plot ( vs T)


Properties of sQGP & Evolving Medium

Temperature of medium?

• Already have chemical Tc - particle ratios

• Thermal photons - First results from PHENIX….

• Low pT spectra with ~5% error bars – data on tape sufficient?

How does medium respond?

• Speed of sound and color di-electric constant

• Trigger jet and away-side correlations

• Mach shockwaves, Cherenkov radiation

• PID intra-jet correlations

What is hadronization, i.e. how is mass generated?

• Effect of chirally-restored medium? Chiral partners? Fragmentation

• PID intra-jet correlations


The sQGP – a Perfect Fluid?

How perfect is our fluid?

• Characteristics of medium & dissipative effects

→ viscosity, heat capacity, speed of sound, diffusion coefficients

• Different quark N fluctuations, v2 , RAA → diffusion coefficients

Ideal hydro → zero viscosity → need viscous hydro calculation

• What is zero viscosity? Much less than that of water! AdS/CFT limit!

• Flow in U + U and at LHC vs hydro limit!

• Study away from mid-rapidity (more viscous and less thermal)

• Study details of light/strange, charm, beauty quarks propagation through

the nearly perfect fluid! Should be different?

My view – “Theory needs to catch up!”

“We must identify more sensitive observables”

• Can we get bulk properties from lattice?

• Bulk (transport) properties from dynamical (or hybrid) model?


Synopsis for sQGP

QGP discovery (without equivocation)!

Many properties of QGP will/still to be determined.

Still to do:

• Establish constituents of sQGP state (EOS)?

• Use heavy flavors, flavor-triggered jets & jets at larger pT!

- as probe of sQGP and response of medium

• Study onium for convincing picture of deconfinement? Tc?

• And ….. whatever happened to chiral restoration?


Jets at


Compelling “Jet Physics” for RHIC & QCD Lab (in LHC-era)*

FQGP (gQGP) = finitial (√s, A1+A2, b, x1, x2, Q2)

fQGP (pT,y , ,pT

jet,y jet ,jet,flavor jet, flow)

Characterizing the sQGP using partons * not complete at LHC!• “Jet” Probes

– High pT identified (light-, s-, c-, b-quark) particles

• fragmentation function modification and flavor dependence

– -jet, - high-pT identified particle, particle-particle, di-jets

• parton energy loss in medium, response of medium• fragmentation function modification, di-hadron fragmentation functions

• Measure over Multi-Parameter Space:– Energy - √s

– Geometry - system A1+A2 , impact parameter b

– Rapidity (x-dependence) to forward angles

– Transverse momentum of jet / leading particle

– Particle type (flavor)

– Orientation relative to flow plane ( flow)

– Photon-tag on opposite side


Detailed “Tomography” of the QGP

/parton

parton

flow plane

FQGP (gQGP) = finitial (√s, A1+A2, b, x1, x2, Q2)

fQGP (pT,y , ,pT

jet,y jet ,jet, flavor jet, flow)

“jet

Renk, HP2006

near

-sid

e

Triggered jets come from near-side surface Di-hadrons penetrate core!

Renk, HP2006

nea

r-si

de

Mach cone phenomenology II

Dijet rapidity correlation Trigger vertex distribution

Rapidity cut effects Flow effects on correlation

Renk - Ruppert, hep-ph/0605330

Renk, nucl-th/0607035

From talk by Berndt Mueller in this Workshop


Jets Broaden Significantly in Pseudorapidity!Kinematics in and pT in pp (+jet) Broadening in and pp AA

AApp

STAR results on correlations for pT < 2 GeV/c

elongation even on near-side!

Large acceptance for ’s, high pT particles, jets (energy)

essential to understand jets, high pT correlations and x-dependence (esp. forward - low x) with tracking + EMCAL (+ ….)

Au+Au, 0-5%200 GeV, || < 0.7 2.5 < pT(trig) < 4 GeV2 < pT(assoc) < pT(trig)


Reminder - Gluon versus Quark Jets

LHC Gluon jets

Top energy RHIC

pT < 20 GeV Gluon jets

pT > 20 GeV Quark jets

Lower RHIC energy

transition from gluon

to quark jets

Utilize RHIC versatility in √s!

-jet and di-hadrons

correlations x x correlations

qg, gg, qq scattering

3-jet events?

STAR Upgrades Workshop – 2 December 2005John Harris (Yale)

+ jet

Direct photons

• pT 10 GeV/c for 1 nb-1

• pT 15 GeV/c for 10 nb-1

Issues of fragmentation ’s Distinguish direct from frag. ’s How does energy loss affect this?

+jet 1% jets have leading hadron > bkgd• Measure away-side frag. function

AuAu (b = 0), s1/2 = 200 GeV

dN

/dyd

2p

T (y

=0)

(G

eV-2c-3

)

q

qg

STARSTAR

+jet yields in STAR

(central Au+Au – long Au + Au run):E= 10 GeV: ~8K ch. hadrons in spectrum

E= 15 GeV: ~1K ch. hadrons in spectrum

Detailed - jet measurements* require luminosity (and increase in coverage)! XN Wang et al

from STAR decadel plan

Note: -jet calibrates di-hadrons & all correlations


Understanding Hadronization, Fragmentation & Medium Modification from Jet Quenching?

Measure fragmentation functions in pp & modifications in AA.

Study z = phadron/pjet and x dependence : 0.2 < z < 1 7 < p < 30 GeV/c 0.1 < x < 0.001 0 < < 3

High pT Identified particlesIntra- and inter-jet particle correlationsLarge acceptance-tagged jets

Each flavor parton contributes differently to fragmentation function

(see Bourrely & Soffer, hep-ph/0305070)

should lose different amounts of energy in opaque medium.

z z

Essential for real “jet tomography”

0.2 < z < 1 7 < p < 30 GeV/c 0.1 < x < 0.001 0 < < 3

2 GeV/c proton in 10 GeV jetAside – effect of heavy quark propagation p/ ratio?


Track-by-track High-pT Particle ID (, K, p) and Jets

< 0.5

pq,g > 10 GeV/c

Multiply pp events by factor of ~ 8 x 1015 for AuAu events in 30 nb-1 RHIC year

Jets at RHIC II (30 nb-1) 180k at 40 GeV

+jet at high ET

for ET = 20 GeV 19,000 + jet events (1000 @ 30 GeV) in 30 nb-1

with high pT PID over full rapidity

pq,g > 10 GeV/call

106 events


Forward Coverage in pp, dA and AAForward emission in hadron collider: QCD analog of low-x deep-inelastic scattering

• Large mid-rapidity acceptance (||<3.4) + forward rapidity (3.5 < || < 4.8)

• Large acceptance - full coverage of recoil parton and PID

Spin effects with rapidity interval correlations

Rapidity interval (forward - mid rapidity)correlations (Mueller-Navelet Jets)

low-x gluon

0.001< xg < 0.1

high-x valence quark

0.3 < xq< 0.7

Gluon

Log

10(

x Glu

on)

For 22 processes

Central Tracking

+ calorimetry + PID

forward detector

frw. det.


Future of Heavy Flavors at

Quarkonium Physics• Deconfinement• QCD Thermometer

Open Charm and Bottom Physics (Do, D*, D±, Ds, B)• Low pT - Thermalization• High pT – Tomography, Transport & other properties of QGP


Quarkonium – Thermometer of Dense QCD

Satz, HP2006

Tmelt(’) < Tmelt((3S)) < Tmelt(J/) Tmelt((2S)) < TRHIC < Tmelt((1S))?

TRHIC > Tmelt(c) , Tmelt(’) , Tmelt((3S))

TLHC > Tmelt(J/) , Tmelt(b) , Tmelt((2S))


Quarkonium Physics

xF dependence:

•Must measure cc feed-down to J/ •Production mechanism studies•Nuclear absorption/shadowing studies•Resolution:

•Acceptance RatesPrecision Tracking + Muon Detectors + EMCAL + PID

Large acceptance for electrons and muons


Charmonium c Feed-down

Broadening in and pT in pp (+jet)

To measure c decay & determine feed-down to J/ c J/ + , must have large forward acceptance for


Heavy Flavor (Quarkonium)

e+e- resolution

• PHENIX (10 nb-1)* e+e-

– with VTX (m = 60 MeV)

– w.o. VTX (m = 170 MeV)

(* 3 - 4 RHIC years of Au + Au)

from PHENIX decadel plan

triggered e+e- resolution– m = 340 MeV for 1s – VTX improves resolution

to m = 170 MeV

STARSTAR

2 hadron suppression factors (tradeoff - efficiency vs background)

from STAR decadel plan

(1s), (2s), (3s) program: e+e- resolution (PHENIX VTX) states unresolved!Statistics?

RHIC-II - Heavy Flavor YieldsAll numbers are first rough estimates (including trigger and reconstruction efficiencies) for 12 weeks physics run (∫Leff dt ~ 18 nb-1)

Signal RHIC Exp. Obtained RHIC I (>2008) RHIC II LHC/ALICE+

J/ →e+e

J/ →

PHENIX ~800

~7000

3,300

29,000

45,000

395,000

9,500

740,000

→ e+e-

→

STAR

PHENIX

-

-

830

80

11,200

1,040

2,600

8,400

B→J/→e+e

B→J/→

PHENIX -

-

40

420

570

5,700

N/A

N/A

c→e+e

c→+

PHENIX -

-

220

8,600

2,900*

117,000*

N/A

N/A

D→K STAR ~0.4×106 (S/B~1/600)

30,000** 30,000** 8000

* Large backgrounds, quality uncertain as yet** Running at 100 Hz min bias+ 1 month (= year), P. Crochet, EPJdirect A1, a (2005) and private comm.

T. Frawley, PANIC’05, RHIC-II Satellite Meeting


Future of Electromagnetic Probes at

Thermal radiation (photons)

Medium modifications of vector mesons• Chiral symmetry breaking• Bound states in sQGP?


EM Probes (Direct Photons) Published Direct Photons from PHENIX

sNN = 200 GeV Au + Au

Thermal photons (1 < pT < 4 GeV/c)?Curves pQCP for pp with binary scalingDirect photons pQCD + binary scaling

Run 4 – definitive!?Benefit from larger L dt ?

Direct Photons from PHENIX – QM05


EM Probes (Virtual Photons via e+e- )• Medium modifications of vector mesons

• Chiral symmetry breaking• Bound states in sQGP ?

• Thermal radiation• May be dominated by charm

R. Rapp nucl-th/0204003R. Rapp nucl-th/0204003

Significant background issues! - e.g. Dalitz, correlated charm decays,....

• requires• ToF

for electrons (pT > 0.2 GeV/c)

• L dt

for detailed charm studies

STARSTAR

• requires• Hadron-blind TPC (HBD)

• L dt

for detailed charm studies


Summary

Planned RHIC Detector Upgrades

QGP discovery and some properties Temperatures (initial, deconfinement)? Constituents?

RHIC Luminosity Upgrade Allows some investigation of c & b physics (transport properties, E-loss) Allows J/ and ’ measurements (c depends on detectors)

Initial look at -jet and hadronization

Some Compelling Physics Awaits Luminosity & Next Generation Det. Systems physics (deconfinement and initial T), Detailed ystematics RHIC ↔ LHC Detailed (PID & flavor-dependent) -jet, intra-jet, jet-jet studies, & hadronization

Don’t forget RHIC’s other Unique Roles Phase(s) of Matter (evolution of CGC → QGP) and investigating tri-critical point New Spin Physics Observables Prospects of the Unknown?

These move us in the era of heavy ions in the QCD Lab …………………..


Heavy Ions in the QCD Lab – Fundamental QUESTIONS Requiring Real Answers

Degrees of Freedom of the sQGP (when, how will we get this?)

Properties of sQGP and characteristics of the phase transition

(when can we describe these to others?)

Evolution of thermodynamic variables predicted from dynamical models

Fundamental properties predicted by fundamental theories - QCD, possibly AdS/CFT,

others….

Color Glass Condensate & evolution to QGP (requires all of above…)

P and CP Violation near the QCD Phase Transition?

Large statistics data samples with reduced systematic errors

Origin of Mass

Understanding hadronization from fragmentation into various flavors

Chiral Symmetry Restoration

fragmentation into resonances in- and out-of-medium, chiral partners???


Heavy Ions in the QCD Lab

Real answers will require next generation RHI Experiment(s) at QCD Lab

This is an absolute necessity for this field to accomplish its goals!!

One such experiment should include:

Large (nearly hermetic) acceptance Identification of all hadrons track-by-track to large momenta Flavor tagging capabilities track-by-track Excellent resolution - track momenta and calorimetry (including ’s)

Other experiments (small and/or large)?


A Comprehensive Detector Concept at the QCD Lab

meters

Lepton sideHadron side

Parton side

Basic Concept


meters


Parton side

Basic Concept

Comprehensive Detector Concept at the QCD Lab

meters


Parton side

Basic Concept


A Heavy Ion Detector Concept for the QCD Lab

HCal and -detectors

Superconducting coil (B = 1.3T)

Vertex tracking

RICH

HC

al a

nd

-det

ecto

rs

Aerogel

EM Calorimeter

ToFTracking: Si, mini-TPC(?), -pad chambers

PID: RICH ToF Aerogel

Forward tracking: 2-stage Si disks

Forward magnet (B = 1.5T)

Forward spectrometer: ( = 3.5 - 4.8) RICH EMCal (CLEO) HCal (HERA)-absorber

|| 1.2

=

1.2 – 3.5

Central detector (| 3.4)

Answers for the RHI program will NOT be complete without an RHI QCD Lab program


Heavy Ions in the QCD Lab – Fundamental QUESTIONS Requiring Real Answers

Degrees of Freedom of the sQGP (when, how will we get this?)

Properties of sQGP and characteristics of the phase transition

(when can we describe these to others?)

Evolution of thermodynamic variables predicted from dynamical models

Fundamental properties predicted by fundamental theories - QCD, possibly AdS/CFT,

others….

Color Glass Condensate & evolution to QGP (requires all of above…)

P and CP Violation near the QCD Phase Transition?

Large statistics data samples with reduced systematic errors

Origin of Mass

Understanding hadronization from fragmentation into various flavors

Chiral Symmetry Restoration

fragmentation into resonances in- and out-of-medium, chiral partners???

john harris (yale) qcd lab workshop, bnl 17 – 22 july 2006 future perspective of heavy ion physics...

Documents

rhic lhc

topology jet energy

leading particles gjet

virtual g e e

rhic detector upgrades

star phenix particle

interjet correlationsresponse

jet large opacity