N. N. Ajitanand Nuclear Chemistry,SUNY, Stony Brook For the PHENIX Collaboration Three-Particle...

N. N. AjitanandNuclear Chemistry,SUNY, Stony Brook

For

the PHENIX Collaboration

Three-Particle Correlations From PHENIX to Investigate the Properties of the QGP

at RHIC

Three-Particle Correlations From PHENIX to Investigate the Properties of the QGP

at RHIC

The 20th International Conference on Ultra-Relativistic Nucleus-Nucleus Collisions (QM2008) Feb. 4 – 10, 2008 Jaipur

N. N. Ajitanand QM2008 2

A Cue from Lattice QCD:A Cue from Lattice QCD:

A Cue from Lattice QCD:A Cue from Lattice QCD:

Phase Transition

12 °

3

170 MeV 10 K

1 GeV/fm

T

Energy density required for QGP formation Energy density required for QGP formation Energy density required for QGP formation Energy density required for QGP formation

Necessary to create Necessary to create εε > 0.6 – 1.0 GeV/fm > 0.6 – 1.0 GeV/fm3 3 in heavy ion collisions in heavy ion collisions Necessary to create Necessary to create εε > 0.6 – 1.0 GeV/fm > 0.6 – 1.0 GeV/fm3 3 in heavy ion collisions in heavy ion collisions


PRL87, 052301 (2001)

Central collisionsperipheral collisions

time to thermalize the system (0 ~ 0.2 - 1 fm/c)Bjorken~ 5 - 15

GeV/fm3

~ 35 – 100 ε0

dy

dE

RT

Bj0

2

11

Extrapolation From EExtrapolation From ETT

DistributionsDistributions

Achieved Energy Density is Well Above theAchieved Energy Density is Well Above the Predicted Value for the Phase TransitionPredicted Value for the Phase Transition

Achieved Energy Density is Well Above theAchieved Energy Density is Well Above the Predicted Value for the Phase TransitionPredicted Value for the Phase Transition

200 GeV Au+Au Collisions 200 GeV Au+Au Collisions studies at RHIC!studies at RHIC!

200 GeV Au+Au Collisions 200 GeV Au+Au Collisions studies at RHIC!studies at RHIC!


Quark scaling of v2 indicates flow sets in at the partonic stage

Strong quenching observed for high pt hadrons

hydro-like flow observed

0.00

0.05

0.10

0.15

0.20

0.25

0.4

0.8

1.21.6

2.0

510

1520

2530

v 2

pT (GeV/c)

Centrality (%)

0.00 0.05 0.10 0.15 0.20 0.25

Au+Au

200 GeVNNs Baryons

s/

P ²

High Energy Density matter produced in 200 GeV Au + Au

High Energy Density matter produced in 200 GeV Au + Au

Initial anisotropy gives large pressure gradients

Initial anisotropy gives large pressure gradients


Even the phi which has a very low hadronic scattering cross-section develops a v2 which scales with the mesons. Strong indication of flow developing at the partonic stage

Phi meson Flow


The same applies to lambdas and cascades

Lambda & Cascade Flow


Observation of significant flow for the D meson which implies charm flow

D Meson Flow


G. D. Moore, D. Teaney hep-ph/0412346

Calculation of the charm spectrum and the elliptic flow as a function of the diffusion coefficient implies surprisingly strong rescattering behaviour for the heavy quark. An indication of the rather special attributes of the matter formed

Charm Diffusion


Such a low value is consistent with the observation of substantial elliptic flow and may provide the conditions for a special medium response to hard probes such as Mach flow

R. Lacey et al. Phys. Rev. Lett. 98,092301 (2007)

The shear viscosity to entropy ratio ( eta /s) is estimated for the hot and dense QCD matter created in 200 GeV Au+Au collisions at RHIC . A very low value is found; eta /s~0.1, which is close to the conjectured lower bound (1/4 pi )

Shear viscosity to Entropy ratio


There is strong evidence to support the view that the medium thermalizes rapidly during the partonic stage and

exhibits a high degree of collectivity.

Study of the medium response to high

pT probes is a natural next step

11

Jets are a natural probe of the Medium

coneRFragmentation:

z hadron

parton

p

p

In relatvistic heavy ion collisions hard parton-parton processes occur early

Scattered partons propagate through the medium radiating gluons and interacting with partons of the medium

Finally partons fragment, (possibly) outside the medium

12

Jet Study via AssortedJet Study via Assorted CorrelationsCorrelations

Associated low pT particle

1.0 2.5 GeV/cpT 1.0 2.5 GeV/cpT

pT

2 ( )P assor High pT Hadron

2.5 4.0 GeV/cpT 2.5 4.0 GeV/cpT

Re al

mix

NC

N

Correlation FunctionCorrelation Function

N(pT)


It is necessary to decompose the correlation function to obtain

the Jet Function!

H(v2)Obtain Obtain

using BBC Reaction PlaneLarge η gap

Two source model gives :

0

HarmoC Jet Functiorrelation Function onic n

C a H J

Correlation Flow Jet Correlation Jet

Sets a0

min 0J

Condition Zero Yield At Minimum

Evaluate a0

Ajitanand et.al. Phys. Rev. C 72, 011902 (2005)Phys. Rev. C 72, 011902 (2005)


Simulation Test of Jet Recovery

Di-jet faithfully recoveredDi-jet faithfully recovered

Normal Jet Shape abnormal Jet Shape

Line : Input Jet Correlation

Squares : Extracted Jet Correlation

15

200 GeV Au+Au : Hadron Jet Shapes

Jet-pair distributions resulting from decomposition showJet-pair distributions resulting from decomposition showsignificant modificationsignificant modification

Jet-pair distributions resulting from decomposition showJet-pair distributions resulting from decomposition showsignificant modificationsignificant modification

PRL 97, 052301 (2006)

200 GeV Au+Au

1<pT<2.5

vs

2.5<pT<4.0

16

MesonMeson vs. vs. BaryonBaryon associated partner (for fixed Hadron associated partner (for fixed Hadron trigger)trigger)

Associated mesons and baryons are similarly modified as would be expectedAssociated mesons and baryons are similarly modified as would be expectedIf in-medium modification is the cause of the away side bending If in-medium modification is the cause of the away side bending

PHENIX Preliminary

17

Armesto,Salgado,Wiedemann hep-ph/0411341

Possible Modifications of Jet Topology

Mach Cone,Wake Effect or “sonic boom” Mach Cone,Wake Effect or “sonic boom”

Stoecker nucl-th/0406018

Muller,Ruppert Hep-ph/0503158

Casalderrey-Solana, Shuryak, Teaney, arXiv hep ph/0411315 (2004)

Flow induced Deflection Flow induced Deflection

Cherenkov Cone Cherenkov Cone A. Majumdar Hard Probes 2006


Three Particle Correlations Used to Extract Jet TopologyThree Particle Correlations Used to Extract Jet Topology

One high pT hadron 2.5<pT<4.0 GeV/Cwith two low pT hadrons 1.0<pT<2.5 GeV/c

Real Triplets formed from one event Correlation FunctionCorrelation Function

Fake Triplets formed from 3 events

Total 3P jet = True 3P jet + (2+1) jet

True 3P jet : all 3 particles belong to the same di-jet

(2+1) jet : 2 particles belong to same di-jet, third one does not

19

along azimuth

Polar plot

3 Particle Correlations in High pT Framework (*)

Normal Jet

Same Side

Away Side

*

*

Assoc. pTs (2,3)

*12

* =

along radius

*12

*13

* _=

Hi pT(1)

Deflected jet sim

3-Particle di-jet correlations allow a distinction between different mechanistic scenarios !

Mach Cone sim

Deflected and Cone Jet Sims

2-particle Correlations matched

High pT(1) High pT(1)

21

PHENIX SIMTest of Harmonic removal

Jet+Harmonic

ZYAM gives good Jet Recovery

Input Jet Harmonic removed

Jet Correlation = Total Correlation – a0*(Harmonic Jet Correlation = Total Correlation – a0*(Harmonic Correlation)Correlation)

““ao” is adjusted till ao” is adjusted till Jet Correlation surfaceJet Correlation surface goes to zero at goes to zero at its minimum (ZYAM )its minimum (ZYAM )

Ajitanand et.al. Phys. Rev. C 72, 011902 (2005)Phys. Rev. C 72, 011902 (2005)

Blue : Input

Red : Recovered

True 3P correlations True 3P correlations successfully recovered successfully recovered

(2+1) correlations obtained taking 2P in event 1 and 1P from event 2

For data relative amounts of soft-soft and hard-soft correlations set by relative strengths of observed 2P correlations

True 3P Correlations absent True 3P Correlations present

Test of (2+1) removal

(2+1) processes (2+1) processes successfully removed successfully removed

Flat Correlation Surface

(offset added)


Pairs per trigger from Correlation

Pairs per trigger Input

Pairs/trigger can be calculated from correlation function knowing detected singles and detected triplets


0-5 % 5-10 % 10-20 %

20-40 % 40-60 % 60-90 %

200 GeV Au+Au Run 7 PHENIX Preliminary

3-particle Correlations without harmonic removal

Total 3-particle Jet Correlation

Strong away side modification in both total and true 3P Jet Correlations

Radial section

True 3-particle Jet Correlation

Jet Correlations

Data

Simulated Deflected jet

Simulated Mach Cone

The data validates the presence of a Mach Cone away-side jet but does not The data validates the presence of a Mach Cone away-side jet but does not rule out contributions from other topologies.rule out contributions from other topologies.

Total 3P jet correlations

True 3P jet correlations

Azimuthal Sections

27

trigger 10 deg in-plane

Jet+flow

Input Jet

flow

(Jet+flow) – flow

(ZYAM)

Radial Projection Radial Projection

SIM Studies of trigger oriented with respect to Reaction Plane

Reaction Plane Dispersion 0.8 (obtained in Run 7)


trigger out-of-plane

Jet+flow

Input Jet

flow

(Jet+flow) – flow

(ZYAM)

Radial Projection Radial Projection


Simulated LHC Event

Phi Eta

Et

Phi

Et

Eta

(PYTHIA + HIJING) PYTHIA JetsJetfinder algorithms

30

Start Step 1

Step 8 Step 20

PYTHIA Jet

A novel method of jet location in an event has been developed which utilizes successive filtering of soft background

using other events

Soft background


Expected triplet jet correlation function for Mach flow signal in LHC events

Once hard jet candidates have been identified in a large number of events, the three-particle correlation method can be applied to look for medium modification


Tsunami : Nature’s awesome medium response to a hard event !!

ConclusionsConclusions

The high pt frame is a suitable choice for the study of jet The high pt frame is a suitable choice for the study of jet topology via topology via 3-3-particle correlationsparticle correlations

3-3-particle jet correlations obtained for 200 GeV Au+Auparticle jet correlations obtained for 200 GeV Au+Au

3-particle 3-particle ccorrelation without harmonic removal for most orrelation without harmonic removal for most central case shows abnormal jet topology central case shows abnormal jet topology

3-3-particle Jet correlationparticle Jet correlationss show strong away side modification show strong away side modification

True 3-particle jet correlations True 3-particle jet correlations validate presence of Mach Cone validate presence of Mach Cone jets but do not rule out smalljets but do not rule out small contributions from other contributions from other topologies. Major implication on limiting viscosity of sQGPtopologies. Major implication on limiting viscosity of sQGP

Method a potential tool for jet study at LHCMethod a potential tool for jet study at LHC

The much improved Reaction Plane resolution achieved in the The much improved Reaction Plane resolution achieved in the high statistics run 7 will allow RP associated cuts on the high pT high statistics run 7 will allow RP associated cuts on the high pT particleparticle

N. N. Ajitanand Nuclear Chemistry,SUNY, Stony Brook For the PHENIX Collaboration Three-Particle...

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