# Presentation: 465993

##       Probes of Jet Topolgy Using Two and Three Particle Azimuthal Correlations 

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

-       **Probes of Jet Topolgy Using Two and Three Particle Azimuthal Correlations **

## High Energy density matter

***High Energy density matter***
***is created at RHIC!***

***Energy Density is Well Above the***
*** ******Predicted Value for the Phase Transition***

***Pressure       Flow***

- N. N. Ajitanand  PANIC2005

## Jets are an ideal probe of the Medium

**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**

- N. N. Ajitanand  PANIC2005

## Possible Modification of Jet Topology

**hep-ph/0411341**
**Armesto,Salgado,Wiedemann**

**hep-ph/0411315**
**Casalderrey-Solana,Shuryak,Teaney**

**Possible Modification of Jet Topology**

**Wake Effect or  “sonic boom”**** **** **

**Correlations of jet fragments with flowing medium**

- N. N. Ajitanand  PANIC2005

## Correlation Functions used to study Jet function

- low pt  particles

- One High pt particle

**Correlation functions provide a robust **
**method for jet study but need removal of flow effects**

**Real : combinations within same event**
**Mix: combinations across different events**

## Removing Harmonic to obtain Jet Function

**i.e. Zero Yield At Minimum (****ZYAM****)**

**a****0**** is obtained  without putting any **
**constraint on the Jet shape by requiring**

**Two source model :  Flow (H) & Jet (J)**

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

**ZYAM**

**Harmonic Extinction**

**High pt particle constrained**
**Perpendicular to RP  **

- N. N. Ajitanand  PANIC2005

## Two Particle correlations

**nucl-ex/0507004**

***Strong centrality dependent modification ***
***of away-side jet in Au+Au***

***Away-side peak consistent***
***with mach-cone scenario***
***Not the only possibility !***

**Cherenkov gluon radiation: nucl-th/0507063 **
**Koch, Majumder, X.-N. Wang**

**Jets and Flow couple: hep-ph/0411341 **
**Armesto,Salgado,Wiedemann**

**Discerning techniques are required !**

**Away side Peak**

- N. N. Ajitanand  PANIC2005

## Trailing jet axis : 
a) Normal jet : aligned wrt leading axis with spread 
b) Deflected jet : 60 deg bent with spread 
c) Cherenkov jet : aligned , no spread 

Leading Jet fragmentation : In a cone  
Trailing Jet axis emission :
Normal jet : In a cone 
Deflected jet : In a cone 
Cherenkov jet : Along surface of cone with 60 deg semi-cone angle

**a) Normal jet : aligned wrt leading axis with spread **
**b) Deflected jet : 60 deg bent with spread **
**c) Cherenkov jet : aligned , no spread**
**Leading Jet fragmentation : In a cone  **
**Trailing Jet axis emission :**
**Normal jet : In a cone **
**Deflected jet : In a cone **
**Cherenkov jet : Along surface of cone with 60 deg semi-cone angle**

**3d Simulation brief **

- “Normal” Jet

- “Deflected” Jet

- Cher. cone

##          Simulated 3-particle jet functions 

- “Normal” Jet

- “Deflected” Jet

- Mach cone

_**         **__**Simulated**_** 3-particle jet functions **
**  ****(3 event mixing i.e.  ****2 + 1 processes not excluded)**

## Experimental 3-particle jet functions

- Flow+Jet

- Jet only

**Experimental 3-particle jet functions**

**Diagonal projection**

**Horizontal projections**

**Jet functions show strong away side modification & hints of “Mach cone”**

- extinction

- PHENIX Preliminary

- PHENIX Preliminary

- PHENIX Preliminary

## Flavor Dependence

**Hadron-Meson-Meson ****(HMM)**

**Hadron-Baryon-Baryon ****(HBB)**

**Flavor Dependence**

**Strong flavor Dependence **
**observed**

**Hadron-Hadron-Hadron (HHH)**

## Centrality Dependence(HHH)

- PHENIX Preliminary

- PHENIX Preliminary

- PHENIX Preliminary

-  20<cent<40

- 40<cent<60

**Centrality Dependence(HHH)**

## Two-particle jet-pair distributions  

**Therefore in the sim study we introduced  kT  and cone width smearing for Cherenkov jets so that  the two particle jet-pair distributions look alike.**

**Recent theoretical studies indicate Cherenkov jets can also suffer from  directional smearing**.

**Satarov et al:**
**Physics Letters B 627 (2005) 64â70**

## New View : Jet Associated Frame

**View associated particles in frame with  high pT direction as z-axis**

**Leading High pT particle**

**Associated **
**particles**

**Several simulation**
**Studies performed **

##  soft –soft -background

**Hi pt from one ev with 2 lo pts in 2nd ev**

**3 ev mix**

-  **soft –soft -background**

-  **hard –soft-background**** **

**3 ev mix**

** ****Hi pt and lo pt from one ev**
** ****with one lo pt in 2nd ev**

**Removal of 2+1 processes using 2 event mixing**

**2 ev mix**

**2 ev mix**

## Simulation results 

**Cherenkov PHENIX accpt****.**

**Deflected jet -  PHENIX Acceptance.**

**Cherenkov full acceptance**

**Simulations indicate  characteristic signatures**

**Deflecte jet  full acceptance**

- Analysis of the data in progress

## Summary

**Three-particle correlation studies underway**
**Initial results give firm indication for:**
**Significant modification of the away-side jet**
**Modifications which show sensitivity to Centrality and particle flavor permutations.**
**Simulation studies suggest that a distinction between deflected jets and Mach cones is possible via three-particle correlation studies.**
**Current results do not support a scenario which excludes Mach cones !**
**Stay tuned**

- N. N. Ajitanand  PANIC2005