# Presentation: 479684

## Conical Emission in Heavy-Ion Collisions

- Jason Glyndwr Ulery
- Purdue University
- 8 February 2008
- Quark Matter 2008

## Outline

- Motivation
- Theory
- Mach-cone shock waves
- Čerenkov gluon radiation
- Experiment
- PHENIX
- STAR
- CERES
- Summary
- Future

- Jason Glyndwr Ulery - Purdue University                            Quark Matter 2008

- 8 February 2008

## Motivation

- Mach-cone in HIC first introduced in 1970s by Hofmann, Stöcker, Heinz, Scheid and Greiner.
- Away-side structure in 2-particle correlations renewed interest.
**Conical emission** is a possible explanation for shape:
**Mach-cone** shock waves
**Čerenkov** gluon radiation
- Other explanations suggested:
- Large angle gluon radiation
- Defected jets
- deflected by radial flow
- path-length dependent energy loss

- STAR
- PRL **95 **152301
- Ulery QM05

- PHENIX
- PRL **97 **052301

- Au+Au

- CERES
- Kniege QM06

- Pb+Au 0-5%

- 0

- 

- 

- 

- /2

- Jason Glyndwr Ulery - Purdue University                            Quark Matter 2008

- 8 February 2008

## Conical Emission

**Mach-cone**:
- Shock waves excited by a supersonic parton.
- Can be produced in different theories:
**Hydrodynamics**
- H. Stöcker et al. (Nucl.Phys.A750:121,2005)
- J. Casalderra-Solana et. al. (Nucl.Phys.A774:577,2006)
- T. Renk & J. Ruppert (Phys.Rev.C73:011901,(2006))
**Colored plasma**
- J. Ruppert & B. Müller (Phys.Lett.B618:123,2005)
**AdS/CFT**
- S. Gubser, S. Pufu, A. Yarom.  (arXiv:0706.4307v1, 2007)
**Čerenkov Gluon Radiation**:
- Radiation of gluons by a superluminal parton.
- I.M. Dremin (Nucl. Phys. A750: 233, 2006)
- V. Koch et. al. (Phys. ReV. Lett. 96, 172302, 2006)
- Parton Cascade
- G. L. Ma et. al. (Phys. Lett. B647, 122, 2007)

- References are only a small subset of those existing.
- Apologies to those not included.

- Jason Glyndwr Ulery - Purdue University                            Quark Matter 2008

- 8 February 2008

**Notes:**
add references

## Čerenkov Gluon Radiation

- Gluons radiated by superluminal partons.
- Angle is dependent on emitted momentum.

- Koch, Majumder, Wang
- PRL **96** 172302 (2006)

- Čerenkov angle vs
- emitted particle momentum

- p (GeV/c)

- Jason Glyndwr Ulery - Purdue University                            Quark Matter 2008

- 8 February 2008

## Mach-Cone

- Mach angle depends on speed of sound in medium
- T dependent
- Angle independent of associated pT.

- Trigger

- Away-side

- PNJL Model

- Mikherjee, Mustafa, Ray
- Phys. Rev. D75 (2007) 094015

- Jason Glyndwr Ulery - Purdue University                            Quark Matter 2008

- 8 February 2008

## Hydrodynamic Mach-Cone

- Energy radiated from the parton is deposited in collective hydrodynamic modes.
- Strength of the correlation dependent on source term which is not fundamentally derived.
- Similar to jet creating a sonic boom in air.

- Cloud formed by a plane
-  breaking the sound barrier.

- Talks by B. Betz and B. Müller Session XIII

- Betz QM08

- Jason Glyndwr Ulery - Purdue University                            Quark Matter 2008

- 8 February 2008

## Colored Modes

- QCD analog of charged particle in plasma from QED.
- Mach-cone is longitudinal modes excited in quantum plasma by a supersonic parton.
- Colored sound.
- Černkov gluon radiation is the transverse mode excited by superluminal parton in the plasma.

- J. Ruppert & B. Müller,
- Phys. Lett. **B618** (2005) 123

- Parallel

- Perpendicular

- Current Density

- Jason Glyndwr Ulery - Purdue University                            Quark Matter 2008

- 8 February 2008

## Ads/CFT

- Mach cone with strong diffusion wake from heavy quarks.
- Mach cone with no diffusion wake for quarkonium.
- No need to add a source term.
- Done is infinitely massive limit.

- Poynting Vector

- shock-wave

- diffusion wake

- Bullet at 2.45cs

- Gubser, Pufu, Yarom
- arXiv:0706.4307v1 (2007)

- Talk by Noronha Session IV

- Jason Glyndwr Ulery - Purdue University                            Quark Matter 2008

- 8 February 2008

## Azimuthal 3-Particle Correlations

- Jason Glyndwr Ulery - Purdue University                            Quark Matter 2008

- 8 February 2008

## Parton Cascade

- Simulated data analyzed from AMPT parton cascade model.
- Backgrounds subtracted through event mixing in similar method to real data.
- Conical emission signal seen.
- What is the mechanism that produces the signal?

- G.L.Ma QM06

- Jason Glyndwr Ulery - Purdue University                            Quark Matter 2008

- 8 February 2008

## Mach-Cone and Flow

- Rapidity distribution and longitudinal flow affects the observed angle and width.
- Transverse flow affects shape of 3-particle correlation.
- signal at ~1 GeV/c ~9x larger if flow and shockwave aligned than if perpendicular.

- Renk, Ruppert,
- Phys. Lett. **B646** 19 (2007)

- Renk, Ruppert,
- Phys. Rev. **C76**, 014908 (2007)

- Jason Glyndwr Ulery - Purdue University                            Quark Matter 2008

- 8 February 2008

## Detectors

- PHENIX has 2 900 wedges in azimuth.
- STAR and CERES have full 3600 azimuthal acceptance.

- STAR at RHIC

- CERES at SPS

- PHENIX at RHIC

- Jason Glyndwr Ulery - Purdue University                            Quark Matter 2008

- 8 February 2008

**Notes:**
maybe just remove this slide

## PHENIX Analysis

- Polar coordinate system relative to trigger particle direction.
- Natural coordinate system if jets are back-to-back in both  and .
- * is angle from trigger.
- * the angle between the two associated particles projected onto plane defined by trigger.
- 2.5<pTTrig<4 GeV/c
- 1<pTAssoc<2.5 GeV/c

- Near Side

- Away Side

- Au+Au 10-20 %

- Ajitanand HP06, IWCF’06

- Poster 243 Ajitanand

- Jason Glyndwr Ulery - Purdue University                            Quark Matter 2008

- 8 February 2008

## PHENIX Simulations

-     Simulations with  PHENIX acceptance.

- Simulated
- Deflected jet

- Ajitanand HP06, IWCF’06

- Poster 243 Ajitanand

- *

- *

- Jason Glyndwr Ulery - Purdue University                            Quark Matter 2008

- 8 February 2008

## PHENIX Results

- 3-particle/2-particle ~ 1/3, very large
- Residual background?

- v2 subtracted     Au+Au 10-20%

- Shape consistent with simulated mach-cone.

- Ajitanand HP06, IWCF’06

- Poster 243 Ajitanand

- Jason Glyndwr Ulery - Purdue University                            Quark Matter 2008

- 8 February 2008

## STAR

- In - space.
- 3<pTTrig<4 GeV/c and 1<pTAssoc<2 GeV/c (except as noted)
- 2-Particle background normalized such that background subtracted 3-particle signal is ZYAM.
- Hard-soft background removes instances where                 1 associated particle is correlated with trigger.

- Raw

- 2-Particle

- Hard-Soft

- Ulery QM05, QM06 (poster)

- Poster: 36 Ma

- Jason Glyndwr Ulery - Purdue University                            Quark Matter 2008

- 8 February 2008

## STAR

- Soft-soft is the background from both associated particles independent of the trigger.
-  Background from the correlations of trigger and associated particles to reaction-plane are added from flow measurements.

- Soft-Soft

- v2(T) v2(1,2)

- v4(T) v4(1,2) +v2(T,1,2)v2(1,2,T) v4(2,T,1)

- Ulery QM05, QM06 (poster)

- Poster: 36 Ma

- Jason Glyndwr Ulery - Purdue University                            Quark Matter 2008

- 8 February 2008

## STAR Results

*pp*

- d+Au

- Cu+Cu 0-10%

- Au+Au 50-80%

- Au+Au 10-30%

- Au+Au 0-12%

- Ulery QM05, QM06 (poster)

- Poster: 36 Ma

- Jason Glyndwr Ulery - Purdue University                            Quark Matter 2008

- 8 February 2008

## STAR Projections and Angle

-     ZDC 0-12% Au+Au shows significant peaks in off-diagonal projection at:
- 	**1.38 ± 0.02 (stat.) ± 0.06 (sys.)** radians

- Ulery QM05, QM06 (poster)

- Talk: Mohanty

- Jason Glyndwr Ulery - Purdue University                            Quark Matter 2008

- 8 February 2008

## STAR Associated PT Dependence

- No significant pT dependence of observed emission angle.
- Consistent with Mach-cone
- Inconsistent with simple Čerenkov radiation

- 0.5<pTAssoc<0.75

- 1<pTAssoc<1.5

- 2<pTAssoc<3

- Ulery QM05, QM06 (poster)

- Poster: P36 Ma

- Poster: 36 Ma

- Jason Glyndwr Ulery - Purdue University                            Quark Matter 2008

- 8 February 2008

## CERES

- 2.5<pTTrig<4.0 GeV/c
- 1.0<pTAssoc<2.5 GeV/c
- Background subtraction method similar to STAR.
- axis ranges are different from STAR

- Kniege QM06, ISMD07

-              Raw                               Hard-Soft                        Soft-Soft                 Trigger Flow (v2v2)

**preliminary**

**preliminary**

**preliminary**

- Poster 251 Appelshaeuser, Kniege, Plokson

- Jason Glyndwr Ulery - Purdue University                            Quark Matter 2008

- 8 February 2008

## CERES Results

- Conical emission peaks are seen.

- hhh

- h+- and h-+

- h++ and h--

**preliminary**

**preliminary**

- Poster 251 Appelshaeuser, Kniege, Plokson

- Kniege QM06, ISMD07

- Jason Glyndwr Ulery - Purdue University                            Quark Matter 2008

- 8 February 2008

## Summary

- Broadened and double-peaked away-side structure in 2-particle correlations.
- Can be explained by conical emission or other physics mechanisms.
- Mach-cone
- Čerenkov gluon radion
- PHENIX
- shape consistent with Mach-cone simulation.
- residual background?
- STAR
- Evidence of conical emission of correlated hadrons at an observed angle of 1.38 radians
- pT independence of the angle suggests Mach-cone emission
- CERES
- peaks consistent with conical emission
- With the aid of theoretical models the extracted angle my provide information on the speed of sound of the medium and the equation of state.

- Jason Glyndwr Ulery - Purdue University                            Quark Matter 2008

- 8 February 2008

## Future Prospects

- New data and detectors will allow for:
- Higher statistics will allow for systematic studies of both trigger and associated pT.
- Helped by increased jet production at LHC
- Identified particle results:
- Mach-cone emission should have a mass dependence in correlation strength
- Full azimuthal TOF detectors ALICE and STAR (upgrade) will provide good PID for these analyses.
- Possible change in angle between SPS, RHIC, and LHC.
- Different initial temperatures
- Many theoretical investigations have been carried out.
- More work is needed to understand what the data tells us about cs and EOS.

- Jason Glyndwr Ulery - Purdue University                            Quark Matter 2008

- 8 February 2008

## Parallel Session xiii

- Medium Response to Jets & Mach Cone

- Jason Glyndwr Ulery - Purdue University                            Quark Matter 2008

- 8 February 2008

- Jason Glyndwr Ulery - Purdue University                            Quark Matter 2008

- 8 February 2008

## Backup

- Jason Glyndwr Ulery - Purdue University                            Quark Matter 2008

- 8 February 2008

## Centrality Dependence

- Jason Glyndwr Ulery - Purdue University                            Quark Matter 2008

- 8 February 2008

## STAR Cumulant

- Done in - space where =Trigger-Associated
- Trigger particles of 3<pT<4 GeV/c.
- Associated particles of 1<pT<2 GeV/c.
- Mathematically Defined.
- Measures all three-particle correlations.

- Pruneau (STAR) QM’06

- C3(12,13) = 3(12,13) - 2(12)1(3) – 2(13)1(2) - 2(12- 13)1(1)
-                        - 2 1(1)1(2)1(3)

- Jason Glyndwr Ulery - Purdue University                            Quark Matter 2008

- 8 February 2008

## STAR Cumulant Results

- Non-zero 3-particle correlation.
- Results contain all possible 3-particle correlations; jet, flow and jet  flow.
- Further interpretation requires model assumptions.
- Non-Poisson fluctuations can leave residual 2-particle correlations.

- Pruneau (STAR) QM’06

- Au+Au 50-80%

- Au+Au 10-30%

- Au+Au 0-10%

- Jason Glyndwr Ulery - Purdue University                            Quark Matter 2008

- 8 February 2008

## STAR With Identified Associated

- Comparison of correlation with identified proton and pion associated.
- Hint of wider peaks for h-pp.

- 2.5<pTTrig<10 GeV/c
- 0.7<pTAssoc<1.4 GeV/c

- Poster: 36 Ma

- Jason Glyndwr Ulery - Purdue University                            Quark Matter 2008

- 8 February 2008

## Cone Signal

- 1.2 pairs/trigger in 3-particle off-diagonal strength ~0.6 (off-diagonal)x4 (peaks)x(0.7x0.7)
- 0.7 particles/trigger ~0.5 (away-side)x2(peaks)x0.7
- (0.7)2=1.2 (assume Poison distribution)
- ~40% (% of triggers with a cone in the acceptance).
- ~2~(0.7/0.4) cone particles per event with cone in acceptance.

- Jason Glyndwr Ulery - Purdue University                            Quark Matter 2008

- 8 February 2008