Unveiling Jet Topology via Multi-Particle Correlations

1

Unveiling Jet Topology via Multi-Unveiling Jet Topology via Multi-Particle CorrelationsParticle Correlations

N. N. Ajitanand

Nuclear Chemistry, SUNY, Stony Brook

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

Brief historical perspective : Brief historical perspective : Brief historical perspective : Brief historical perspective :

For phase transition to occur necessary to create For phase transition to occur necessary to create energy density > 0.6 – 1.0 GeV/fmenergy density > 0.6 – 1.0 GeV/fm3 3

For phase transition to occur necessary to create For phase transition to occur necessary to create energy density > 0.6 – 1.0 GeV/fmenergy density > 0.6 – 1.0 GeV/fm3 3

N. N. Ajitanand Jyvaskyla 2007 3

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


lambdas and cascades also show strong v2 according to the expected scaling pattern further supporting the view that flow sets in at the partonic stage

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. Strongly coupled liquid ?

Charm Diffusion


Although a part of this effect may be trivially related to the contribution of resonances, the possibility of medium modification contributions is an interesting area of investigation.

PHENIX Data to be published in PRL

One way to do this would be to look at the source function at different orientations with respect to a high pt particle

Imaging Studies

Source functions extracted for charged pions produced in Au+Au collisions show non-Gaussian tails.


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 ~0.1 is found 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

12

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

Following hard collisions, scattered partons propagate through the medium radiating gluons and interacting with partons of the medium

Finally partons fragment, (possibly) outside the medium

13

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

nucl-ex/0501025 Ajitanand et. al.


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

16

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

17

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

18

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

19

J. Friess, S. Gubser, G. Michalogiorgakis, S. Pufu

hep-th/0607022

Graviton perturbations of AdS_5-Schwarzschild generated by a string trailing behind an external quark moving with constant velocity are studied. Mach cone signals are generated in the medium

Components of the stress tensor exhibit directional structures in Fourier space at both large and small momentum. The Mach cone angle seen is similar to that in the experiment

ADS-CFT duality


Dip

Sh

ould

er

Sh

ould

er

Identify “Mach Cone ” region with shoulder and normal jet region with dip

Analysing two-particle Jet correlations from Mach cone perspective


Dip to Shoulder ratio vs pT for different trigger pT ranges

Behaviour for Au+Au is quite different from p+p indicating medium modification


Shoulder does not quench rapidly medium dominanceDip quenches rapidly jet dominance

The away side Icp

( )

( )cent

peripheralCP

PerTrigYield

PerTrigYieldI

Ratio of per-trigger yield: Icp

23

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)

24

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)

25

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)

26

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

28

3-particle Correlations without harmonic removalPHENIX Preliminary

Data

Most central shows jet dominated landscape with strong away side modification

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

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


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

30

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


Simulated LHC Event

Phi Eta

Et

Phi

Et

Eta

(PYTHIA + HIJING) PYTHIA JetsJetfinder algorithms

32

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


Conclusions

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

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

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

3-particle Jet correlations show strong away side modification

True 3-particle jet correlations validate presence of Mach Cone jets but do not rule out contributions from other topologies.

Method a potential tool for jet study at the LHC


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

Documents

Unveiling Jet Topology via Multi-Particle Correlations