heavy ion caf é 1 st meeting ~experiment side~

Heavy Ion Café Heavy Ion Café 11stst meeting meeting

~Experiment side~~Experiment side~K. OzawaK. Ozawa

Univ. of TokyoUniv. of Tokyo

2006/12/9 Heavy Ion Cafe 2

Signatures of QGPSignatures of QGP

K. Yagi, T. Hatsuda, and Y. Miake, “Quark-Gluon Plasma”

(1) Average transverse momentum(2) Volume (3) Enhance of strangeness and charm(4) Enhance of anti-particles

(5) Elliptic flow (v2)

(6) Fluctuations conserved charges

(7) Suppression of high-pT hadrons

(8) Heavy quarkonium(9) Modification of light vector mesons(10) Thermal photons and dileptons

(1)

(2)

(3)

(4)

(5)

(6)

(7)

(8)

(9)

(10)


In RealityIn Reality

(1) Average transverse momentum(2) Volume (3) Enhance of strangeness and charm(4) Enhance of anti-particles

(5) Elliptic flow (v2)

(6) Fluctuations conserved charges

(7) Suppression of high-pT hadrons

(8) Heavy quarkonium(9) Modification of light vector mesons(10) Thermal photons and dileptons

pT spectrum

HBT Heavy flavorParticle ratio Elliptic flowEvent-by-Event fluctuation

Ratio to expectation (RAA)

J/and Ylight vector mesons ()Photons and electron pairsNear and away side Jet


Our activities and HI CafeOur activities and HI Cafe

pT spectrum

HBT Heavy flavorParticle ratio Elliptic flowEvent-by-Event fluctuation

Ratio to expectation (RAA)

J/and Ylight vector mesons ()Photons and electron pairsNear and away side Jet

T. Chujo (M. Konno)A. EnokizonoF. Kajihara and S. SakaiM. Konno (T. Chujo)H. Masui and S. ShimomuraT. NakamuraT. IsobeT. Gunji and S. OdaY. Nakamiya (and K. Ozawa)K. Ozawa

実際に解析をしている人に話してもらって、各回にテーマを決めて、議論していきたい


Focus on Jet quenchingFocus on Jet quenching

• At RHIC, we can use high pT particles to diagnose the medium.

• Measuring high pT particle yields:– Initial yields and pT distributions can be predi

cted from p+p measurements + pQCD + cold nuclear effects

– Deviations can be attributed to the medium formed in A+A collisions

• High pT particles (leading particles of jets) as 0, can be measured in large BGs (dNch/d ~ 700)

A+A

p+p


ObservablesObservables

• Yield suppression by medium effects– Comparison with p+p

• Nuclear modification factor (RAA)

.

2

2

/

/

/)(

inelcollAA

TNN

AA

TAA

TAA

NT

ddpNdT

ddpNdpR

– Light (and Heavy) mesons

• Two (or three) particle correlation

00, , measurementsmeasurements


T

The p+p ReferenceThe p+p Reference• Measurement at 200 GeV

•nucl-ex/0610036

0


nucl-ex/0610036

Initial State Effects?Initial State Effects?

• New PHENIX paper on centrality dependence of 0+ in d+Au at 200 GeV

• d+Au as collision system to look for initial state effects

=> no strong initial state effects

nucl-ex/0610036


Au+Au at 200 GeVAu+Au at 200 GeV• data from RHIC run 2004

p (GeV/c)

T

<Peripheral to Central Au+Au Collision>

•Stronger Suppression for more central collision.

0 RAA is flat for all centrality for pT>5 GeV/c.

•Difference between 0 and charged increases for pT < 5 GeV/c.

RRAAAA at 200 GeV at 200 GeV


Au+Au at 200 GeV (Au+Au at 200 GeV ())• data from RHIC run 2004


RRAAAA at 200 GeV ( at 200 GeV ())• in Au+Au

=> Suppression by a factor of 5 in central events


RRAAAA at 200 GeV at 200 GeV• Direct , 0 and in Au+Au

– Direct RAA with measured p+p reference!

=> RAA of and 0 consistent, both show suppression=> RAA of is smaller than 1 at very high pT

0-10% central events


RRAAAA at Different Energies at Different Energies

• Comparison of 0 in Cu+Cu at 200, 62.4, and 22.4 GeV– Measured the same c

ollision species over a broad energy range

• Suppression gets larger with higher energies


RRAAAA at Different system size at Different system size

Both behave same at mid central.


SPS and RHICSPS and RHIC

• Same behavior for similar Npart (63 at WA98, 67.8 at PHENIX)

Blattnig parameterization used for WA98 data (S. Blattnig et. al., Phys.Rev. D62 (2000) 094030 / D. D’Enterria, Phys. Lett. B 596 (2004) 32))


Summary ISummary I

• Strong suppression up to 20 GeV• suppression patternsof 0 and are simi

lar• Clear Collision Energy dependence• Consistent results for the same system siz

e and the same energy

Do these results mean jet energy loss in the medium?


Comparison with modelsComparison with models

C. Loizideshep-ph/0608133v2

I. Vitev

W. HorowitzUse RAA to extract medium density:

I. Vitev: 1000 < dNg/dy < 2000

W. Horowitz: 600 < dNg/dy < 1600

C. Loizides: 6 < < 24 GeV2/fmq̂

Statistical analysis to make optimal use of dataCaveat: RAA folds geometry, energy loss and fragmentation


What do we learn from RWhat do we learn from RAAAA??

~15 GeV

E=15 GeV

Energy loss distributions very different for BDMPS and GLV formalisms

But RAA similar!

Renk, Eskola, hep-ph/0610059

Wicks et al, nucl-th/0512076v2

BDMPS formalismGLV formalism

Need more differential probes


RRAAAA vs. Reaction Plane vs. Reaction PlaneAu+Au collisions at 200GeV nucl-ex/0611007

In Plane

Out of Plane

In plane emission shows no energy loss in peripheral bins.

3<pT<5 GeV/c

L


RRAAAA L L Dependence DependenceAu+Au collisions at 200GeV

L = matter thickness calculated in Glauber model

Little/no energy loss for L< 2 fm

0-10%

50-60%

nucl-ex/0611007


33

33

dpdT

dPNdpR

ppAA

AATAA

p+p reference:

Data (converter) for pT<1.6 [GeV/c]

1.71*FONLL for pT>1.6 [GeV/c]

Suppression level is the almost same as 0 and in high pT region

Heavy FlavorHeavy Flavor


Summary IISummary II

• Several theoretical models can reproduce the experimental data.

• To investigate the origin of yield suppression, need more probes

• Reaction plane dependence of RAA is measured. Clear dependence on matter thickness is shown.

• Measurements for Heavy flavor show the similar results in high-pT.

Two or Three Two or Three particle particle

correlationcorrelation


correlations at RHICcorrelations at RHIC– “Trigger-associated” technique valuable for

tagging jets in high-multiplicity environment (vs. jet-cone algorithms)

– Probes the jet’s interaction with the QCD medium

– Provides stringent test of energy-loss models

correlations

TriggerAssociated

Associated

Higher pT → Away-side suppression

Pedestal&flow subtracted

STAR, PRL 91 (2003) 072304 STAR, nucl-ex/0501016

Lower pT → Away-side enhancementpT(assoc) > 2 GeV/c pT(assoc) > 0.15 GeV/c

4 < pT(trig) < 6 GeV/c


Dijet assoc. yields (IDijet assoc. yields (IAAAA) vs. R) vs. RAAAASTAR, Phys. Rev. Lett. 91 (2003) 072304

• Near-side yields consistent with unity

• Away-side associated yields similar to RAA values

IAA = Yield(0-5% Au+Au) Yield(d+Au)

= Near-side IAA

= Away-side IAA

8 < pT(trig) < 15 GeV/c


Centrality dependenceCentrality dependence


ZZTT Distribution Distribution

• Yield in |Δφ|>0.9• ZT = pT assoc/pT

trig


IIAAAA

IAA = Yield(0-5% Au+Au) Yield(d+Au)


Shape analysisShape analysis

On this figure,

Shape

analysis is

done.


Away side peak shapeAway side peak shape

• 3 fitting functions are used.

• Shifted peak is at almost constant


Jet Functions (PHENIX)Jet Functions (PHENIX)

224

2

/

)(

kurtosis

rms

nn

nucl-ex/0611019

rms, kurtosis and D also independent of pT of associated hadrons - poses challenge to color Cerenkov models

D

)(

)()(

)(

DG

DGG

J


InterpretationsInterpretationsMach Cone/Shock wave

T. Renk, J. Ruppert

Stöcker, Casseldery-Solana et al

Cherenkov radiation Gluon rad+Sudakov

A. Polosa, C. Salgado

V. Koch, A. Majumder, X-N. Wang

Many explanations possible, need more input to conclude

Or large kT from radial flow or energy loss Fries, Armesto et al, Hwa

Also: Vitev, Phys. Lett. B630 (2005)


3-particle correlations3-particle correlations

1

3

12

0

13

12

0

Event by event deflection of jets

Cone like structure in each event

3-particle - probes away-side structure:Distinguish event-by-event deflection vs conical (Mercedes) emission pattern

1: 3 < pt < 4 GeV/c (Jet Tag)2,3: 1 < pt < 2 GeV/c,


Centrality 0-12%

12

1

3

Diagonal and Off-diagonal structures are suggestive of conical emission at an angle of about 1.45 radians in central Au+Au.

Deflected Jet + Cone

Cone

Near Side

Elongated Away Side Jet

Jet - Flow Subtraction ResultJet - Flow Subtraction Result


3-Particle Correlations3-Particle Correlations

*

High pT (1)

Assoc. pTs (2,3)

Same Side

Away Side

(3 particles from di-jet) + (2 from dijet + 1 other)

PHENIX Preliminary

*

*12

*13

* _=

*12

=

*=

*=


Correlation TopologiesCorrelation Topologies

*

Cone Jet

Deflected Jet

Normal Jet

* Azimuthal Section:

(medium excitation)

(scattered jet axis)

(unmodified)

PH

EN

IX S

imul

atio

n

*

*

trip

les/

trig

ger

(A.U

.)

PHENIX Preliminary

*=

*=

PHENIX Preliminary


Near-Side ModificationNear-Side Modification0-10% Central Cu+Cu

I AA =

CY

AA/C

YP

P

0-20% Central Au+AuTrigger pT


3<pt,trigger<4 GeV

pt,assoc.>2 GeVAu+Au 0-10%

preliminary

Near side Near side -- Correlations Correlations• Near-side long range

correlation in – STAR, nucl-ex/0509030– near side “ridge”

Phys. Rev. C73 (2006) 064907

mid-central AuAupt < 2 GeV

d+Au, 40-100% Au+Au, 0-5%

3 < pT(trig) < 6 GeV2 < pT(assoc) < pT(trig)

0.8< pt < 4 GeVnucl-ex/0607003See Poster by Ron Longacre

/√

ref


-Jet Correlations-Jet Correlations

decay

inclusivehdecayhinclusivehdirect RY

RY

RY

)1

(/11

1

Inclusive -h

Decay -h contribution(via 0-hadron)

Direct -h !

p+p collisions at 200 GeV

hdirectinclusive

directhdecay

inclusive

decayhinclusive YYY


Comparison to PythiaComparison to Pythia


-Jet Correlations in AuAu-Jet Correlations in AuAu

Poster: M. Nguyen, N. GrauTalk: J. Jin (2.2.07)


Summary IIISummary III

• We can see a clear away side suppression in two particle correlation.

• In addition, away side broadening exists.

• Analysis for three particle correlation is done. It suggests conical emission.

heavy ion caf é 1 st meeting ~experiment side~

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