W.A. Zajc

The Science with RHIC and Its Upgrade

W.A. ZajcColumbia University

IUPAP WG-9 SymposiumJuly 2-3, 2010, TRIUMF

02-Jul-10

With my explicit thanks to E. Aschenauer, A. Deshpande, J. Dunlop, W. Fischer, J. Nagle,

E. O’Brien, K. Rajagopal, T. Roser, S. Vigdor ;

and implicit thanks to all my colleagues at RHIC

W.A. Zajc

Assertion

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Fact QCD is our prototypical non-Abelian

gauge theory4 Amenable to experimental study at both

strong and weak coupling4 Deep connections to other gauge theories

RHIC is the only facility dedicated to the study of QCD4 In the thermal regime4 Using perturbative probes to study

non-perturbative phenomena

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U.S. Long Range Planning in Nuclear Science

A source of considerable community pride Something we’re good at The plans are ‘resource burdened’ We’ve been at it for a long time:

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1983 1989 1996 2002 2007

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We’re Good at It and Have Been For a Long Time

A case in point – the Relativistic Heavy Ion Collider (RHIC)

1983 Plan:4 “We identify a relativistic heavy ion collider as the

highest priority for the next major facility to be constructed, with the potential for addressing a new scientific frontier of fundamental importance.”

2000: RHIC begins operations 2005: Announcement of major discoveries

at RHIC02-Jul-10

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Discovery 2005

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2007 Long Range Plan Recommendation #4

The experiments at the Relativistic Heavy Ion Collider have discovered a new state of matter at extreme temperature and density — a quark-gluon plasma that exhibits unexpected, almost perfect liquid dynamical behavior.

• We recommend implementation of the RHIC II luminosity upgrade, together with detector improvements, to determine the properties of this new state of matter.02-Jul-10

W.A. Zajc02-Jul-10

The RHIC Discovery

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A RHIC Mission

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The RHIC Discovery

RHIC’s Bounty

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A RHIC Mission

Understand the spin structure of the proton

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SqDq

DG

Lg

SqLq dq1Tf

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RHIC Spin RHIC is the world’s only polarized proton

collider:

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RHIC Spin RHIC is the world’s only polarized proton

collider:

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RHIC Spin RHIC is the world’s only polarized proton

collider. Use pQCD to study how the proton spin

is distributed among its constituents:

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pQCD at RHIC (I)

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STAR: PRL97, 252001 (2006)

PHENIX: PRD76 051106 (2007)

Establishing the validity of pQCD at RHIC energies essential to both the spin and the heavy ion programs:

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pQCD at RHIC (II) Spin: pQCD is

4 absolutely essential for reliable, quantitative extraction of polarized distribution functions(next slide)

Heavy ions: pQCD is4 absolutely essential for

reliable, quantitativemeasurement of “jet quenching”

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Gluon Contribution DG to Proton Spin

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RHIC

Dg(x) g+(x) – g-(x) In global analysis, RHIC data already play

dominant role in constraining Dg(x) for x < 0.2 : Future measurements

with > x10 increase in integrated luminosity4 Greatly reduced errors

in putative(?) negative Dg(x) 4 Photons, heavy flavor4 Di-hadron, jet-jet, g-jet

to provide direct measurement of Dg(x) x-dependence

20012005

2008

2012 ?

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Angular Momentum Contributions to Proton Spin

Observation of large single spin transverse asymmetries at large |xF| at RHIC:

Potential to understandorbital motion of partonsin the proton

In particular4 Test “non-universality”

of Sivers function4 Clear prediction of sign

change between DIS and Drell-Yan(D-Y to be measured at RHIC, luminosity hungry!)

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Sea Quark Contribution to Proton Spin Via “self-analyzing” W production (!) 2009: 500 Gev run: proof of principle (~10 pb-1)

First spin results (!) Future:

4 10 pb-1 300 pb-1 PHENIX m triggerSTAR GEM tracker

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A RHIC Mission

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A RHIC Mission

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The RHIC Discovery

“Perfect Liquid” behavior of the quark-gluon plasma

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Expectations circa 2000

• As encoded in the Nuclear Physics Wall Chart,• http://www.lbl.gov/abc/wallchart/

• RHIC would create a quark-gluon plasma;

a “gas” of weakly interacting

quarks and gluons

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2010 – First Temperature Measurement

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PHENIX, PRL 104:132301, 2010 Ti ~ 300-500 MeV

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Clearly in Deconfined Regime Ti ~ 400 MeV quark and gluon d.o.f. “dominant”

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But - The Quark-Gluon Plasma is Not a Gas

Prejudice circa 2000:4 Protons and neutrons would

‘sublimate’ to a gasof quarks and gluons

4 Much like dry ice

Discovery circa 20054 The quark-gluon plasma

is a nearly perfect liquid4 Something like regular

ice to water

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Long Range Plan Recommendation

The experiments at the Relativistic Heavy Ion Collider have discovered a new state of matter at extreme temperature and density — a quark-gluon plasma that exhibits unexpected, almost perfect liquid dynamical behavior.

• We recommend implementation of the RHIC II luminosity upgrade, together with detector improvements, to determine the properties of this new state of matter.02-Jul-10

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Perfect Fluids Perfect fluids are characterized by low viscosity. Low viscosity requires strong coupling.

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Perfect Fluids Perfect fluids are characterized by low viscosity. Low viscosity requires strong coupling.

Precisely the region studied with RHIC energies.02-Jul-10

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RHIC and the Phases of Nuclear Matter

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Heavy Ions at the LHC Offers an unprecedented increase in energy:

4 RHIC sNN = 0.2 TeV4 LHC sNN = 5.5 TeV

4 5.5 / 0.2 = 27.5 (!)

Estimate for change in initial temperature Ti :

4 Ti(LHC) = (27.5)1/4 Ti(RHIC) ~ 2.3 Ti(RHIC)

4 N.B.: LHC matter will still evolve through ‘RHIC’ temperature regime

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RHIC and LHC

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RHIC LHC

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Two Scenarios Scenario 1: Matter at LHC similar to RHIC

4 LHC will study with much higher Q2 probes New observables new discoveries

4 RHIC will study with greater flexibility in Running time, energies and species Baseline (p+p) measurements Control (p+A, d+A) measurements

Scenario 2: LHC weakly-coupled, RHIC strongly-coupled4 LHC will probe fundamentally new regime4 RHIC uniquely able to study strongly-coupled QGP

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The Future RHIC Program “We recommend implementation of the RHIC II

luminosity upgrade…4 Underway! (technological breakthrough)

~1/7 the cost ~ 4 years early

…together with detector improvements … 4 Underway

…to determine the properties of this new state of matter.”4 Thermodynamics, equation of state of perfect liquid4 Search for the critical point in its phase diagram

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The “RHIC II” Luminosity Upgrade

1/7 the cost and 4 years early ?

Yes !4 Breakthrough –

stochastic cooling in a bunched collider

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• Y h+v pickups• B h+v

kickers

• B h+v pickups• Y h+v kickers

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The “RHIC II” Luminosity Upgrade

1/7 the cost and 4 years early ?

Yes !4 Breakthrough –

stochastic cooling in a bunched collider

4 2010: RHIC operates at ~ 10 x design luminosity

4 Full stochastic cooling (2012) provides 20 x design luminosity

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• 14 Jan 2010

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Building On Success First decade of

RHIC Operations: dramatic successes

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Operated modes (beam energies):Au–Au 3.8, 4.6, 5.8, 10, 32, 65, 100 GeV/nd–Au* 100 GeV/n Cu–Cu 11, 31, 100 GeV/np–p 11, 31, 100, 250 GeV Planned or possible future modes:Au – Au 2.5 GeV/n (~ AGS cm energy)p – Au* 100 GeV/n (*asymmetric rigidity)

Achieved peak luminosities (100 GeV, nucl.-pair):Au–Au 1551030 cm-2 s -1

p–p 501030 cm-2 s -1

Other large hadron colliders (scaled to 100 GeV):Tevatron (p – pbar) 351030 cm-2 s -1

LHC (p – p, design) 1401030 cm-2 s -1Initial Discoveries

pb-1

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“… together with detector improvements …”

Underway. Examples:

4 PHENIX Muon trigger (W’s) VTX (central Si) FVTX (forward Si)

4 STAR Forward GEM tracker (W’s) Heavy Flavor Tracker

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“… to determine the properties of this new state of matter.”

Example: How strong is the coupling ? Surprising discovery: heavy flavor

(charm, perhaps bottom) 4 Loses energy in medium4 Flows with the medium

despite MHF >> TQGP

The Si Vertex upgrades+ “RHIC II” luminositieswill separate the contributions of b and c quarks to this result

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QCD Condensed Matter “Perfect Liquid” – a new state of matter

(energy)4 One that emerges from a fundamental Lagrangian

The ultimate condensed matter physicsNo (?) dependence on ‘accidental’ scales like me/mp .

“RHIC II” goal: to measure medium properties Examples:

4 Debye screening length4 Equation of state4 Jet quenching ( dE/dx )4 Shear viscosity4 Bulk viscosity

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mm MFFDiL aa

ˆ~41

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The ultimate “outreach” of the ultimate condensed matter physics

Conjectured quantum bound of 1 / 4p

We need to firmlyestablish RHIC point(s)

Shear Viscosity

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Current Status of h/s Extraction To do: Vary

4 s4 Mass4 Probe

(c, b)4 Shape

( 238U ) All

enabled by upgraded RHIC

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Chaudhuri, arXiv:010.0979

Luzum and Romatschke, arXiv:0804:4015

Chaudhuri, arXiv:0909.0391

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The Phases of QCD

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Transition to QGP at highest RHIC energy is “infinite order”

First-order phase transition expected at lower energy.

WHERE ?

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The QCD Critical Point

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The landscape’skey feature .

RHIC uniquely bridges GSI LHC

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The QCD Critical Point

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The landscape’skey feature .

RHIC uniquely bridges GSI LHC

Requires RHIC to be run as low energy collider

Search via non-monotonic trends in fluctuations

Search underway Precision may

await further luminosity upgrades

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A RHIC Mission

02-Jul-10

The RHIC Discovery

W.A. Zajc

A RHIC Mission

02-Jul-10

The RHIC Discovery

RHIC’s Bounty

Potential to study even more than what has been presented here.

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Gluon Saturation

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Glue dominates the low-x structure of nucleons: In nuclei,

saturation scale Qs

2 ~ A1/3 Q02 .

Naturally studied in4 p+A and/or d+A collisions4 Upgrades to STAR and PHENIX enable

“3rd ” RHIC program dedicated to saturation physics Natural connection to

4 Initial state in A+A at RHIC (and LHC)4 Electron Ion Collider (see talk by A. Deshpande)

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QCD Surprises Local strong parity violation ?

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STAR PRL 103:251601,2009

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Local Strong Parity Violation? Requires

Strong magnetic field (~1017 G)Deconfined quarks (plausible)4 QCD topological charge (TBD)

Discovery requires4 Elimination of all

mundane effects4 Excitation function4 Study in

Isobaric pairs (e.g., 9644Ru and 96

40Zr) Asymmetric collisions (e.g., Cu+Au)

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The Big Picture The strongly-coupled fluid at RHIC has created

unique ties to other fields:

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AdS/QCDPerfect liquid

AdS/CFTPrediction of

h/s bound

AdS/CMTCold atomic gases

Strongly correlated electrons

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The Bigger Picture The AdS/CFT correspondence forges a fascinating

link between4 Semi-classical gravity4 Strongly-coupled gauge theories

In some sense, it ‘works best’ when4 Coupling is as strong as possible4 System is thermal

RHIC !02-Jul-10

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Summary RHIC’s unparalleled versatility

4 Has led to major discoveries4 Provides a dedicated environment for study of

Thermal QCD Spin structure of proton Saturation physics

Recent advances in 4 Luminosity and accelerator capability4 Detector upgrades

establish a future program of extraordinary promise.

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Thank You !

With my explicit thanks to E. Aschenauer, A. Deshpande, J. Dunlop, W. Fischer, J. Nagle,

E. O’Brien, K. Rajagopal, T. Roser, S. Vigdor ;

and implicit thanks to all my colleagues at RHIC02-Jul-10