conical emission in heavy-ion collisions

Conical Emission in Heavy-Ion

Collisions

Jason Glyndwr UleryPurdue University8 February 2008

Quark Matter 2008

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

2

Outline

• Motivation• Theory

• Mach-cone shock waves• Čerenkov gluon radiation

• Experiment• PHENIX• STAR• CERES

• Summary• Future


3

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 152301Ulery QM05

PHENIX PRL 97 052301

Au+Au

CERESKniege QM06

Pb+Au 0-5%

0

/2


4

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.


5

Čerenkov Gluon Radiation

• Gluons radiated by superluminal partons.

• Angle is dependent on emitted momentum.

)(

1

)(cos

pnvpn

c

v

c

partonc

parton

n

Koch, Majumder, WangPRL 96 172302 (2006)

Čerenkov angle vs emitted particle momentum

p (GeV/c)


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Mach-Cone

Mparton

s

v

c cos

• Mach angle depends on speed of sound in medium • T dependent

• Angle independent of associated pT.

cvp

c partons

;2

Trigger

Away-side

PNJL Model

Mikherjee, Mustafa, Ray

Phys. Rev. D75 (2007) 094015

MM


7

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


8

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 D

ensity


9

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


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Azimuthal 3-Particle Correlations

Mediumaway

near

deflected jets

away

near

Medium

Conical Emission

Medium

away

near

di-jets


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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?

background subtracted3-particle correlation signal

G.L.Ma QM06


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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)


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Detectors

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

acceptance.

STAR at RHIC CERES at SPSPHENIX at RHIC


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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<pT

Trig<4 GeV/c• 1<pT

Assoc<2.5 GeV/c

**

Trigger

Plane Normal to Trigger

Near Side

Away Side**

Near-Side

*=

Au+Au 10-20 %

Ajitanand HP06, IWCF’06

Poster 243 Ajitanand


15

PHENIX Simulations

Simulations with PHENIX acceptance.

Simulated Deflected jet

Simulated Mach Cone

*=0



* *


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PHENIX Results

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

v2 subtracted Au+Au 10-20%

v2 and 2-particle subtracted

* Projections

v2 subtracted

2-particle dominated2-particle dominated

Mach-cone

Deflected

• Shape consistent with simulated mach-cone.

PRL 97, 052301 (2006)

PHENIX




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STAR

• In - space.• 3<pT

Trig<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


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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)


Poster: 36 Ma


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STAR Resultspp 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


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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

Conical emission peaks


Talk: Mohanty


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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<pT

Assoc<1.5 2<pTAssoc<3


Poster: P36 Ma

Poster: 36 Ma


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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)

prel

imin

ary

prel

imin

ary

prel

imin

ary

Poster 251 Appelshaeuser, Kniege, Plokson


23

CERES Results

• Conical emission peaks are seen.

hhh h+- and h-+ h++ and h--

prel

imin

ary

prel

imin

ary

Poster 251 Appelshaeuser, Kniege, Plokson

Kniege QM06, ISMD07


24

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.


25

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.


26

Parallel Session xiii

•Medium Response to Jets & Mach Cone


27


28

Backup


29

Centrality Dependence


30

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.

3(12 ,13)

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)

2 (12)1(3)2 (13)1(2) 2 (23)1(1)


31

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%


32

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


33

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.

conical emission in heavy-ion collisions

Documents

ulery qm05phenix prl

adscftmach cone

supersonic parton

conical emissionmachcone

parton cascadeg

mller phys

ruppert phys

erenkov gluon radiationgluons