Soft sector: promises, promises...

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June 2005 mike lisa - Cracow School of Theoretical Physics, XLV - Z akopane Poland 1 Soft sector: promises, promises... ~ 10 GeV/fm 3 >> C (Bjorken / hydro) Early thermalization (v2 / hydro) T chem ~ T H ~ T c ~ 170 MeV b ~ 30-40 MeV -- near baryon free connection to lattice? further evolution (PdV work?) & expansion leading to... cooling and bulk collective motion (pT spectra, v2, HBT, K-) Can we use an external probe to explore further?

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Soft sector: promises, promises.  ~ 10 GeV/fm 3 >>  C (Bjorken / hydro) Early thermalization (v2 / hydro) T chem ~ T H ~ T c ~ 170 MeV  b ~ 30-40 MeV -- near baryon free  connection to lattice? further evolution (PdV work?) & expansion leading to... - PowerPoint PPT Presentation

Transcript of Soft sector: promises, promises...

Page 1: Soft sector: promises, promises...

June 2005 mike lisa - Cracow School of Theoretical Physics, XLV - Zakopane Poland 1

Soft sector: promises, promises...

~ 10 GeV/fm3 >> C (Bjorken / hydro)

• Early thermalization (v2 / hydro)

• Tchem ~ TH ~ Tc ~ 170 MeV

b ~ 30-40 MeV -- near baryon free connection to lattice?

• further evolution (PdV work?) & expansion leading to...

• cooling and bulk collective motion (pT spectra, v2, HBT, K-)

Can we use an external probe to explore further?

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June 2005 mike lisa - Cracow School of Theoretical Physics, XLV - Zakopane Poland 2

Discovery and Properties: The Ideal Experiment

The first exploration of subatomic structure was undertaken by Rutherford at Manchester in 1909 using Au atoms as targets and particles as probes.

incoming electron(controlled probe)

scatteredelectron

Can we do the same at RHIC?

QGPNOBut we can get close ………

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Fast Partons (Quarks & Gluons) Traversing Matter

• Jets:

– high-pT parton produced in a hard (high-Q) scattering process

– Calculable in QCD (at high-pT)

– partons fragment into many correlated white hadrons

• emitted in a cone

– created early in the collision quark

quark

hadrons

hadrons

leading particle(highest-p particle)

p+p sNN=200 GeV

PHENIX PRL 91 241803 (2003)

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June 2005 mike lisa - Cracow School of Theoretical Physics, XLV - Zakopane Poland 4

Fate of jets in heavy ion collisions?

p

p

?

Au+Au

idea: p+p collisions @ same sNN = 200 GeV as reference

?: what happens in Au+Au to jets which pass through medium?

QuickTime™ and aTIFF (LZW) decompressor

are needed to see this picture.The tail probes the bulk

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The Ubiquitous RAA…

Nuclear overlap model to calculate # incoherent NN collisions (no shadowing etc)

RAA = (# seen in nuclear collision) / (# expected)

(PHENIX notation: f=centrality cut)

5x fewer high pT particles than “expected” in AuAu

Required checks:• saturation (initial-state) effect?

20

0 G

eV

0 R

AA

PHENIX (and all others) PRL2003

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The control experiment: d+Au, 2003

?

Au+Au

Aud

AuAu

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Centrality Dependence

• Dramatically different and opposite centrality evolution of Au+Au experiment from d+Au control.

• Jet Suppression is clearly a final state effect.

Au + Au Experiment d + Au Control Experiment

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June 2005 mike lisa - Cracow School of Theoretical Physics, XLV - Zakopane Poland 8

The Ubiquitous RAA…

Nuclear overlap model to calculate # incoherent NN collisions (no shadowing etc)

RAA = (# seen in nuclear collision) / (# expected)

(PHENIX notation: f=centrality cut)

5x fewer high pT particles than “expected” in AuAu

Required checks:• saturation (initial-state) effect?

• d-Au null result• hard scattering rates understood?

• measure “robust” hard processes

20

0 G

eV

0 R

AA

PHENIX (and all others) PRL2003

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June 2005 mike lisa - Cracow School of Theoretical Physics, XLV - Zakopane Poland 9

Hard non-mesonic (“direct”) photons & non-photonic (“charming”) electrons

NB: pT-integrated

PHENIX QM04

PHENIX 2004

• Created in earliest, hardest parton scatterings & conserved thereafter

• binary scaling √• (probably some Cronin inside errors)

• probe-once-created and creation itself in AA are “calibrated” (better than d-Au)

PHENIX

Direct photons visiblebecause 0 is suppressed!!

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June 2005 mike lisa - Cracow School of Theoretical Physics, XLV - Zakopane Poland 10

The Ubiquitous RAA…5x fewer high pT particles than

“expected” in AuAu

Required checks:• saturation (initial-state) effect?

• d-Au null result• hard scattering rates understood?

• measure “robust” hard processes• charm / direct follow Nbinary

20

0 G

eV

0 R

AA

PHENIX (& all others): PRL 2003

Accepted view• final state effect is partonic energy loss

in color-charge-dense(not necc. deconfined) medium

= 15 GeV/fm3 @ = 0.2 fm• ~ consistent w/ BJ and hydro…

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June 2005 mike lisa - Cracow School of Theoretical Physics, XLV - Zakopane Poland 11

The Ubiquitous RAA…5x fewer high pT particles than

“expected” in AuAu

Required checks:• saturation (initial-state) effect?

• d-Au null result• hard scattering rates understood?

• measure “robust” hard processes• charm / direct follow Nbinary

20

0 G

eV

0 R

AA

PHENIX (& all others): PRL 2003

Accepted view• final state effect is partonic energy loss

in color-charge-dense(not necc. deconfined) medium

= 15 GeV/fm3 @ = 0.2 fm• ~ consistent w/ BJ and hydro…

is it “jet” quenching?Go beyond leading particles

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June 2005 mike lisa - Cracow School of Theoretical Physics, XLV - Zakopane Poland 12

Beyond leading particles

STAR p+p event

find this…

STAR Au+Au event

…in this

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June 2005 mike lisa - Cracow School of Theoretical Physics, XLV - Zakopane Poland 13

Jets via azimuthal correlations

STAR p+p event• trigger: highest pT track, pT>4 GeV/c

• distribution for 2<pT<pTtrigger

• normalize to number of triggers

trigger PRL 90, 082302

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June 2005 mike lisa - Cracow School of Theoretical Physics, XLV - Zakopane Poland 14

Jets via azimuthal correlations

STAR Au+Au event

Try the same in Au-Au(large combinatorics)…

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Azimuthal distributions in Au+Au

pedestal and flow subtracted

PRL 90, 082302

Central collisions:• strong suppressionof away-side jet

Peripheral collisions:• very similar to p+p

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Further geometric detail

midcentral (20-60%) collisions

nucl-ex/0407007

Suppression depends on pathlength thru medium

This analysis: cannot be initial state effect

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June 2005 mike lisa - Cracow School of Theoretical Physics, XLV - Zakopane Poland 17

anything new in-between?

?

Probes of the system (hard)• interesting results• important open questions

System itself (soft)• interesting/important results• important open questions

If we bridge the gap (“firm”)?

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June 2005 mike lisa - Cracow School of Theoretical Physics, XLV - Zakopane Poland 18

Connecting the sectors

• hydro breaks down above~ 2 GeV/c (expected)

• mass systematic meson/baryon systematic?

•definitely not hydro!

symmetry, thermal smearing

mass syste

matic

v2 generatedby anisotropicenergy loss?

soft-firm connection: v2

P. Sorensen, SQM04

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June 2005 mike lisa - Cracow School of Theoretical Physics, XLV - Zakopane Poland 19

soft-firm connection: v2

• hydro breaks down above~ 2 GeV/c (expected)

• mass systematic meson/baryon systematic?

•definitely not hydro!

v2 generatedby anisotropicenergy loss?

PID-differentialmeson/baryon systematic!

hard-firm connection: RAA

BUT!…

Connecting the sectors

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June 2005 mike lisa - Cracow School of Theoretical Physics, XLV - Zakopane Poland 20

PR

L 92

(20

04

) 05

23

02

Non-hydro / non-E origin of firm v2?

meson/baryon (i.e. constituent quark number) systematics suggest…

coalescence (“recombination”) of already-flowing (!!) partons (*)

* well, constituent quarks

v2hadron (pT

hadron ) ≈ nv2quark (pT

quark )

pThadron ≈ npT

quark

PR

L 92

(20

04

) 05

23

02

P. Sorensen, SQM04

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A growth industry...

Many model variantsLin, Molnar, Pratt,Fries, Bass, Mueller,Ko, Das, Levai, Hwa,Greco, Voloshin, Nonaka…

Many schemes, all describe “anomalous” B/M, RAA, v2

But, data themselves (IMHO) clearly indicate exciting, collective partonic behaviour

Hope for a “hadronization testbed”?

… for a thermal source

Baryons compete with mesons

Fragmentation wins out for a power law tail

B. Mueller TBS05

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June 2005 mike lisa - Cracow School of Theoretical Physics, XLV - Zakopane Poland 22

bulk, collective system ~ 10 0

Tch~ TC ~ 170 MeV; b~30 MeV

Tkin~100 MeV, flow~0.7c

hydro worksearly thermalization.sensitivity to early-stage EoS

“calibrated” probes:final state effectcolor-dense mediumnew at RHIC (?)sensible geometrical systematics ~ 10 0

baryon / meson systematicsunexpected!(constituent?) partonic collectivity?![possibility to test hadronization

mechanisms?]

high pT

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June 2005 mike lisa - Cracow School of Theoretical Physics, XLV - Zakopane Poland 23

Open Issues

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soft sector questions

• hydro and v2

– hydro “limits” ?

– EoS - does Lattice really work

• RHIC HBT “puzzle”

– puzzle #1: failure of (otherwise-successful) dynamical models

– puzzle #0: generic “failure” - no sign of P.T.

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June 2005 mike lisa - Cracow School of Theoretical Physics, XLV - Zakopane Poland 25

hydro “limit”?

we have a bad history in RHI

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Trends, soft sector, and RHI historyMotivation Formalism Experiment Trends Models

Art’s talk. Compiled byA. Wetzler (2005)

6 decades of E/A(2 decades of sNN)Gyulassy 1995

Just oneevent!

Finally, weunderstand it!

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June 2005 mike lisa - Cracow School of Theoretical Physics, XLV - Zakopane Poland 27

hydro “limit”?

Kolb, Sollfrank, Heinz, PRC62 054909 (2000)

dN/dy

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June 2005 mike lisa - Cracow School of Theoretical Physics, XLV - Zakopane Poland 28

Disintegration timescale

Relative momentum between pions is a vector can extract 3D shape information

p2

p1

q

12Kpp=+rrr

Rout

Rlong – along beam direction

Rout – along “line of sight”

Rside – “line of sight”

Rside

increases with emission timescale

rq =

r p 1 −

r p 2

rK =

r p 1 +

r p 2

↔ Rout

Rside

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June 2005 mike lisa - Cracow School of Theoretical Physics, XLV - Zakopane Poland 29

Disintegration timescale - expectation

3D 1-fluid Hydrodynamics Rischke & Gyulassy, NPA 608, 479 (1996)

withtransition

withtransition

“” “”

Long-standing favorite signature of QGP:

• increase in , ROUT/RSIDE due to deconfinement confinement transition

• expected to “turn on” as QGP energy threshold is reached

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June 2005 mike lisa - Cracow School of Theoretical Physics, XLV - Zakopane Poland 30

Disintegration timescale - observation

• no threshold effect seen

• RO/RS ~ 1

4

6

8

4

6

8

1.0

1.25

1.5R

O (

fm)

RS (

fm)

RO

/ R

S

increasing collision energy

RHIC

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Disintegration timescale - observation

• no threshold effect seen

• RO/RS ~ 1

• toy model calculations suggest very short timescales

F. Retiere & MAL, PRC 70 (2004)

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Disintegration timescale - observation

PCM & clust. hadronization

NFD

NFD & hadronic TM

PCM & hadronic TM

CYM & LGT

string & hadronic TM

N()

Heinz & Kolb, hep-ph/0204061

• no threshold effect seen

• RO/RS ~ 1

• toy model calculations suggest very short timescales• rapid, explosive evolution• too explosive for “real” models

which explain all other data

An important space-time“puzzle” at RHIC

- actively under study

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June 2005 mike lisa - Cracow School of Theoretical Physics, XLV - Zakopane Poland 33

STAR, PRL93 012301 (2004)

Measured final source shape

centralcollisions

mid-centralcollisions

peripheralcollisions

Expected evolution:

2x

2y

2x

2y

RR

RR

+−

20,S

22,S

FO R

R2≈

• estimate INIT from Glauber

• from asHBT:

Shape evolution: never goes in-plane?

STAR PRL93 (2004) 012301

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firm/hard sector questions

• firm

– entropy issue (I really don’t care - theorists will work it out)

– what is a “dynamical constituent quark”?

• hard

– no consistent energy loss scenario describing geometrical systematics of energy loss (Miodosewski/Tannenbaum)

– is charm quenched? What about dead cone?-- can it be gluon radiation?

– both issues do we really understand the energy loss mechanism?

– if not, how can we say we probe color density

– and, if so, what can we say besides color density (e.g. deconfined or not)

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20

0 G

eV

0 R

AA

PHENIX (& all others): PRL 2003

The Ubiquitous RAA…5x fewer high pT particles than

“expected” in AuAu

Common wisdom:• d-Au null effect final state effect

• so obvious that initialdAu = AuAu?

• look at other hard probes from same initial processes, but withno final state effects…

Common wisdom II:• final state effect is energy loss in

color-charge-dense(not necc. deconfined) medium

= 15 GeV/fm3 @ = 0.2 fm• ~ consistent w/ BJ and hydro…

Important result!Several complicated (& diff) ways to get suppression?Several canceling effects?

Look closer in a more natural way…

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June 2005 mike lisa - Cracow School of Theoretical Physics, XLV - Zakopane Poland 38

If we are looking at energy loss…

…why quantify downward shift of spectrum (as in RAA)?

PHENIX PRL 2003

It seems more natural to quantify leftward shift.[Tannenbaum/Mioduzewski]

NB: ignores• Cronin (see jets() coming up…)• mods in FF (logical to look at shift of

partons not their fragments)

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ÿ p-p 0 spectrum: power law:

dn

dpT

2=

A

pT

n with n = 8.1 ±0.1

ÿ p T shift , UTloss

UT

UT

ST pSpSpp )1()( −=−=

o pTU = pT with no energy loss

o pTS = pT with energy loss

o Sloss = (pTU- pT

S)/ pTU

= fraction of pT lost

)2/(11 −−= n

AAloss RS

…then let’s look at energy lossEmpirical energy loss

Tannenbaum/Mioduzewski

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June 2005 mike lisa - Cracow School of Theoretical Physics, XLV - Zakopane Poland 40

ÿ p-p 0 spectrum: power law:

dn

dpT

2=

A

pT

n with n = 8.1 ±0.1

ÿ p T shift , UTloss

UT

UT

ST pSpSpp )1()( −=−=

o pTU = pT with no energy loss

o pTS = pT with energy loss

o Sloss = (pTU- pT

S)/ pTU

= fraction of pT lost

)2/(11 −−= n

AAloss RS

Initial pathlength dependence seems to work

–Gyulassy, Vitev, Wang:

• 1D expansion, simple geometric scaling Well reproduced by experimental data.

3/2partNE ∝

PHENIX prelimAu+Au √sNN=200 GeV

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June 2005 mike lisa - Cracow School of Theoretical Physics, XLV - Zakopane Poland 41

Vary pathlength another way…

PHENIX prelimAu+Au √sNN=200 GeV

(deg)

qualitatively OK, now see about consistency…

PHENIX B. Cole, HardProbes 04

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No universal loss versus density path?

dncolor

dA∝

dnpart

dA

ρρ 0init

colorcolor )( =Txr

PHENIX preliminar

y

pT > 3 GeV/c

Overlapintegral:

1Dexpansion

ρpart(x,y) vs centrality10-20% 50-60%

• Quantitative consistency required to claim “jet tomography”

• Next level of precision needed to clarify underlying quenching mechanism

• also -tagging, charm/dead-cone, q/g jet selection, correlated quenching signal versus length

• (Role of dynamics in differential analysis may be significant)• cannot just put by-hand some energy loss & find consistency w/BJ

PHENIX B. Cole, HardProbes 04

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June 2005 mike lisa - Cracow School of Theoretical Physics, XLV - Zakopane Poland 43

PHENIX Preliminary

RAA (2.5<pT<5.0 GeV/c)

Nu

clea

r m

odif

icat

ion

fac

tor

Converter method

Cocktail subtraction method

pT (GeV/c)

HINT of charm suppression??

Too early to tell (May05)

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June 2005 mike lisa - Cracow School of Theoretical Physics, XLV - Zakopane Poland 44

Backup

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Parton Number Scaling of Elliptic Flow

In the recombination regime, meson and baryon v2 can be obtained from the parton v2 (using xi = 1/n):

( ) ( )

3

2

2 2

2

2

22

2

2

3v 32v2

v

1 2 v

v3 3

v

1 6 v32

and

p pt t

B

p t

Mt t

p tp t

p p

p

p

pp p

⎛ ⎞⎛ ⎞ ⎛ ⎞+⎜ ⎟ ⎜ ⎟⎜ ⎟

⎛ ⎞⎜ ⎟⎝ ⎠=

⎛ ⎞⎛ ⎞+ ⎜ ⎟⎜ ⎟

⎝ ⎠ ⎝ ⎠⎝ ⎠=⎛ ⎞⎛ ⎞

+ ⎜ ⎟⎜ ⎟⎝ ⎠⎝⎠ ⎠⎠⎝

Neglecting quadratic and cubic terms, a simple scaling law holds:

( ) ( )2 2 2 2an vv23

vd2

v 3M B ptt

tp tpp

pp

⎛ ⎞=

⎛ ⎞= ⎜ ⎟

⎝⎜⎝ ⎠ ⎠

Originally poposed by S. Voloshin

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June 2005 mike lisa - Cracow School of Theoretical Physics, XLV - Zakopane Poland 46

Suppression vs Collision Energy

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NO suppression in d+Au!

BRAHMS

Phobos

STAR

PHENIX

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Hadron dependence of high-pt suppression

• R+F model describes different RAA behavior of protons and pions

• Jet-quenching becomes universal in the fragmentation region

Mueller & Fries [Mueller TBS05]

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June 2005 mike lisa - Cracow School of Theoretical Physics, XLV - Zakopane Poland 49

Centrality dependence of open charm in Au+Au

Compare to (PYTHIA) an event generator tuned for pp collisions…

no largesuppression- unlike lightquarks!

Spectra of electrons from c e + anythingphotonic sources are subtracted

central

peripheral

Comparison to pp should be available this week.

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inclusive ee v2

charmed ee v2

If charm quarks also flow, charm quarks are thermalized and / or suppressed (interact with matter) similarly to the light quarks.

STAR SQM04

nucl-ex/0502009

•charmed electron v2 > 0•rule out an extreme case, charm does not interact with QGP and fragment in vacuum into D meson•get charm quark v2 with quark coalescence assumption

Flowing Charm? [F. Laue TBS05]

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June 2005 mike lisa - Cracow School of Theoretical Physics, XLV - Zakopane Poland 51

Inclusive Single

PHENIX Preliminary

Run2 AuAu 200 GeV

Direct photons are enhanced w.r.t. production, but it’s just because is suppressed, and the direct photons are in fact binary scaled.

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June 2005 mike lisa - Cracow School of Theoretical Physics, XLV - Zakopane Poland 52

STAR : nucl-ex/0409033 non-flow reduced

v2{2}

v2{RP}

PHENIX Preliminary

Different ways to reduce non-flow correlation, v2 w.r.t. SMD R.P.

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Sonic boom from quenched jets Casalderrey,ES,Teaney, hep-ph/0410067; H.Stocker…

• the energy deposited by jets into liquid-like strongly coupled QGP must go into conical shock waves, similar to the well known sonic boom from supersonic planes.

• We solved relativistic hydrodynamics and got the flow picture

• If there are start and end points, there are two spheres and a cone tangent to both

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away <pT> dependence on angle (STAR,preliminary)

Preliminary

<pT> (phi) has a dip structure in central AA.

Mach shock wave?

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June 2005 mike lisa - Cracow School of Theoretical Physics, XLV - Zakopane Poland 55

Viscosity of QGP

QGP at RHIC seem to be the most idealfluid known, viscosity/entropy =.1 or so water would not flow if only a drop with 1000 molecules be made

• viscous corrections1st order correction to dist. fn.:

:Sound attenuation length

Velocity gradients

Nearly ideal hydro !? D.Teaney(’03)

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Comparison Au+Au/p+p at Lower Energies

• Pb+Pb collisions at s ~ 20 GeV at CERN/SPS

Crossing at ~ 1.5 GeV/c

Transverse Momentum (GeV/c)

parton energy loss (if any) is overwhelmed by initial state soft multiple scattering(Cronin effect)

RA

A

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June 2005 mike lisa - Cracow School of Theoretical Physics, XLV - Zakopane Poland 57

Many measurements measure at high pT(!)

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What data can tell us / what (we think) it has told us /open issues

• Hard Sector:

–incoherence of initial state

• calibration of number of initial hard scatterings (binary), which themselves have calibrated spectrum [charm, gamma, d-Au]

–early system color charge density (not deconfinement!)

• if gluonic bremstrahlung: dNg/d ~ 1000 ~BJ

• BUT… energy loss mechanism unclear (consistent scaling?)

• relevant upcoming data:–charm quench (early results limited) / dead cone effect-tagged jets

–q/g jet selection

–higher stats correlated quenching signal versus length

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What data can tell us / what (we think) it has told us /open issues

• Soft sector:

–“threshold behaviour”

• no evidence: “evolution, not revolution”: too bad but not a killer

–degree to which it is system - real collectivity

• solid evidence from several observations - very important [perfect fluid?]

–global/thermodynamic properties: T, , P, • consistent with deconfinement - [but! may be P.S. dominance]

– dynamics - system response evolution and timescales

• 2x expansion, collective shape evolution

• timescales- correct dynamic signatures, wrong (x,t) evolution??

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What data can tell us / what (we think) it has told us /open issues

• Firm Sector:–“transition bulk to probe” (hadn’t really been considered…)

• clearly something new instead!• ?is there a transition? does all fit smoothly?

–first “calibration” of QGP p.s. structure• hope for well-defined ordered (x-p correlated) system of partons • can we get beyond simple models? entropy issues? connection

between constituent quarks and partons?…

My feeling: solution of open issues in hard & soft sectors willbe well worth it, if we can exploit apparent promise of firm.

Launchpad of next generation program: understanding hadronization