Conical Correlations in Heavy-Ion Collisions

Conical Correlations inHeavy-Ion Collisions

Barbara Betz

Thanks to: Miklos Gyulassy, Jorge Noronha, Dirk Rischke, Giorgio Torrieri

Phys. Rev. C 79, 034902 (2009), Phys. Lett. B 675, 340 (2009), Nucl. Phys. A 830, 777c (2009), arXiv:1005.5461

2 09/13/10 MIT Seminar, Boston Barbara Betz

Conical Correlations in HICWhat are „conical correlations in heavy-ion collisions“?

Correlations revealing the creation of Mach cones???

Experiment:Review on experimental studies

Conclusions and Outlook

Theoretical approaches:Jets & hydrodynamicsDifferent energy-loss mechanisms

What could they tell us about the medium created?

Fluctuating initial conditions, v3(carrying coals to Newcastle)

Why we need to study heavy-flavor tagged jetsDeflection of wakes due to transverse flow „Conical“

signal

3

HIC Facilities

initial state

pre-equilibrium

expanding fireball

hadronization

hadronic phaseand freeze-out

S. Bass, Talk Quark Matter 2001

RHIC

FAIR

LHC

09/13/10 MIT Seminar, Boston Barbara Betz

RHIC, BNL: 2000 – … p+p, d+Au, Cu+Cu,

Au+Au LHC, CERN: 2008/9 - … p+p, Pb+Pb FAIR, GSI: ~2016 - … accelerates ions from p

to U

4

2 Major RHIC Results


5

Reproducing the elliptic flow v2

P. Romatschke and U. Romatschke, Phys. Rev. Lett. 99,172301 (2007)

Medium behaves like an almostideal fluid

/s

BNL press release, April 18 2005.


Particles don‘t interact,

expansion independent

of initial shape

Particles interact,expansion

determined by density gradient

„dust“ fluid

Data can be described by hydrodynamics

with small

Fluid-like Medium

6

Jet Quenching• Like in medicine, hard probes can be

used to investigate the medium properties

• If created matter is opaque, a jet depositing its energy should eventually disappear jet suppression

STAR, Phys. Rev. Lett. 91 (2003) 072304

4 < pTtrigger < 6 GeV/c

pTassoc > 2 GeV/c

What can the energy lost tell us about the medium properties?

Trigger particle

University Wuppertal, “Schul-Vorlesungen zur Physik”



Jets in HIC I

By observation: Confirm fast

thermalization Study EoS of the fluid

Mach cone angle sensitive to EoS

Can energy lost by jets tell us something about medium properties?

IF the medium behaves like a fluid: Mach cones have to occur because

offluid dynamics

4 < pTtrigger < 6 GeV/c

0.15 < pTassoc < 4 GeV/cAu+Au / p+p

= 200 GeVs

PHENIX, Phys. Rev. C 77, 011901 (2008)

8

Jets in HIC II

STAR, Nucl. Phys. A 774, 129 (2006)

Reflect interaction of jet with medium

• Redistribution of energy to lower pT-particles

• Re-appearance of the away-side for low and intermediate pT

assoc

H. Stöcker, Nucl. Phys. A 750, 121 (2005), J. Casalderrey-Solana et al. Nucl. Phys. A 774, 577 (2006)


9

Experimental Studies


10

STAR, Phys. Rev. C 82, 024912 (2010)see also PHENIX, Phys. Rev. C 77, 011901 (2008)

Position of away-side

peaks does not change

strongly with pTassocNot due to

Cherenkov gluonradiation

What happens to larger pT

trigger?

Jet - Studies in HIC I


11

Investigation of path length dependence:Double-peaked structure becomes

morepronounced out-of-plane

A. Sickeles [PHENIX], Eur. Phys. J. C 61, 583 (2009)

Jet - Studies in HIC II


Could be due to deflection

12

Centrality dependence:

double-peaked structure for central collisions

one peak structure for very peripheral collisions

PHENIX, Phys. Rev. Lett. 97, 052301 (2006)

J. Jia, Eur. Phys. J. C 62, 255 (2009)

Jet - Studies in HIC III

Energy Scan:

double-peaked structure occurs at about the same angle for different collision energies Mach cone???09/13/10 MIT Seminar, Boston Barbara Betz

13

Some caveats


14

Background Subtraction

How can one proof/disproof

the two-source model?J. Ulery [STAR], PoS LHC07, 036 (2007)

D. d’Enterria and BB., Springer Lecture Notes (2008)


Assumption (Two-source model) :

No correlations between flow anisotropy

and jets ZYAM (Zero Yield At Minimum) Subtraction of:estimated elliptic flow modulatedbackground can leads to:double peaked structure

Background:Particle

correlation from elliptic flow

15

3-Particle Correlations

J. Ulery [STAR], Int. J. Mod. Phys. E 16, 2005 (2007)

ptrigT=3 – 4 GeV, passoc

T=1 – 2 GeV Three-particle correlations

seem to corroborate Mach cone idea

- What’s the effect of ZYAM?- No agreement with 3-particle

cumulant methodC. Pruneau, Phys. Rev. C 79, 044907 (2009)


Deflected jet

Mach Cone

ptrigT>3 GeV, passoc

T=1 – 2 GeV

C. Pruneau, Talk at the Workshop on ‘Critical Asessment of Theory and Experiment on Correlations at RHIC’, BNL, February 2009

16

Theoretical Approach


17

Modelling of Jets

STAR, Phys. Rev. Lett. 95, 152301 (2005)

residue of energy and momentum given by the jet

• Assumption of isochronous/isothermal freeze-

out • No interaction afterwards

mainly flow driven

Conversion into particles Freeze-out:

Jets can be modelled using (ideal) hydrodynamics:

e+p v.

Medium created in a HIC can be described using hydrodynamics


18

The Static Medium


19

Stopped Jet IApplying a static medium and an ideal Gas EoS for massless

gluons Assume: Near-side jet is not modified by medium

Maximal fluid response

Jet decelerating from v=0.999according to Bethe-Bloch

formalism a=-1.36

GeV/fm

Simplest back-reaction from the medium

Bragg Peak

adjusts path length

BB et al., Phys. Rev. C 79, 034902 (2009)


20

Stopped Jet II

Mach cone forsound waves Diffusion

wake

dE dM GeV(0) v (0) 1.5dt dt fm= = t=4.5/v

fmdE GeV dM GeV(0) 1.5 (0) 0dt fm dt fm= =

BB et al., Phys. Rev. C 79, 034902 (2009)


21

Stopped Jet III

Diffusion wake causes peak in jet direction

Normalized, background-subtracted isochronous Cooper-Frye at mid-rapidity

Energy Flow Distribution

Assuming: Particles in subvolume will be emitted into the same direction

pT = 5 GeV

BB et al., Phys. Rev. C 79, 034902 (2009)

Any conclusions about deposition mechanism???09/13/10 MIT Seminar, Boston Barbara Betz

22

Stopped Jet IV• Jet stops after t=4.5/v

fm

dE GeV(0) 1.5dt fmdM GeV(0) 0dt fm

=

=

dE GeV(0) 1.5dt fmdM GeVv (0) 1.5dt fm

=

=

Vorticity conservation

tFO=4.5/v fm

tFO=6.5/v fm

tFO=8.5/v fmDiffusion wake still

present

BB et al., Phys. Rev. C 79, 034902 (2009)


23

Stopped Jet V

tFO=4.5/v fm

tFO=6.5/v fm

tFO=8.5/v fm

Diffusion wake causes peak in jet direction

Larger impact of thermal smearing

BB et al., Phys. Rev. C 79, 034902 (2009)


24

A Comparison


25

BAMPS: Boltzmann Approach of MultiParton ScatteringsA transport algorithm solving the Boltzmann equations for

on-shellpartons with pQCD interactions

C. Greiner, Talk at the Opening Symposium of the JET Collaboration, Berkeley, June 2010

Box scenario, no expansion, massless Boltzmann gas interactions, 2 -> 2

The shock front (Mach front) gets broader and vanish with more dissipation09/13/10 MIT Seminar, Boston Barbara Betz

Mach Cones in Transport


Different Jet-Energy Loss Modells


Modelling Jets using …

Conclusion about Mach cones?

pQCD

AdS/CFT

P. Chesler and L. Yaffe, Phys. Rev. D 78, 045013 (2008)

R. Neufeld et al, Phys. Rev. C 78, 041901 (2008)

Strongly-coupled theory

Pointing vector perturbation

Momentum density perturbation

Energy density perturbation

Energy density perturbation

Weakly-coupled theory

v=0.75

v=0.99955


Non-Mach correlations caused by Neck region

Jets in AdS/CFT

J. Noronha et al., Phys. Rev. Lett. 102, 102301 (2009)


Heavy Quark Jets


Heavy Quark JetsCompare weakly and strongly coupled models using heavy punch-

through jetpQCD: Neufeld et al. source for a heavy quark

AdS/CFT: Stress tables with/s=1/(4 ) R. Neufeld et al, Phys. Rev. C 78, 041901 (2008)

pT = 3.14 GeV

BB et al., Phys. Lett. B 675, 340 (2009)

No Mach-like peaks:AdS/CFT: Strong influence of the Neck region

Static medium and isochronous freeze-out needed for comparison

t=4.5/v fmS. Gubser et al, Phys. Rev. Lett. 100, 012301 (2008)

BB et al., Phys. Lett. B 675, 340 (2009)

J. Noronha et al., Phys. Rev. Lett. 102, 102301 (2009)


The Expanding Medium

32

Expanding Medium I

Consider different jet paths

b=0

• Apply Glauber initial conditions and an ideal Gas EoS for massless gluons• Focus on radial flow contribution

Experimental results based

on many eventsA. K. Chaudhuri, Phys. Rev. C 75, 057902

(2007) ,A. K. Chaudhuri, Phys. Rev. C 77, 027901

(2008)

• Two-particle correlation (Tfreeze-out < Tcrit = 130

MeV):

near-side jet

dE/dt = 1 GeV/fm

Jet 150

Etot = 5 GeV


33

Expanding Medium IIEtot = 5 GeV

broad away-side peak double peaked structure

due to non-central jets

pTtrig = 3.5

GeV

PHENIX, Phys. Rev. C 77, 011901 (2008)

vjet =0.999

BB et al., arXiv: 1005.5461


34

Expanding Medium IIIEtot = 10

GeV

Strong impact of the Diffusion wake

broad away-side peak double peaked structure

Causes smaller dip for pT=2 GeV

pTtrig = 7.5

GeV

6 < pTtrigger < 10

1.5 < pTassoc < 2.5

f

Yiel

dPath length dependence Centrality

dependence09/13/10 MIT Seminar, Boston Barbara Betz

STAR, Phys. Rev. C 82, 024912 (2010)

35

Expanding Medium IVComparing different deposition scenarios, one

sees that„cone“ angle approximately the same for different deposition scenarios

pTassoc = 2.0 GeV: No double-peaked structure for pure energy

deposition scenario due to thermal smearking

pTtrig = 3.5

GeV pTassoc = 3.0

GeVpT

assoc = 2.0 GeV

vjet =0.999



36

Expanding Medium V

Conical emission angle also appears for subsonic jets

Not a Mach cone

Considering a bottom quark (M=4.5 GeV), propagating at vjet < cs

(on-shell energy-momentum deposition scenario) pTassoc = 2.0

GeV

Cu+Cu: Similar away-side shoulder width, double-peak structure reappars for pT

assoc = 3 GeV


PHENIX, PRL98, 232302 (2007)


37

Some more caveats


38

Hot Spots ICan fluctuating initial condition explain the 2+3-particle

correlations?Takahashi et al, PRL 103, 242301 (2009)

F. Grassi, Talk at the Glasma Workshop, BNL, May 2010

R. Andrade et al., arXiv: 0912.0803


39

Hot Spots IICheck with one single hot

spot

Heavy quark jets are not affected 09/13/10 MIT Seminar, Boston Barbara Betz

Au, De/e0=0.2

40

Fluctuating Initial Conditions


41

Initial Fluctuations IP. Sorensen J. Phys. G 37, 094011 (2010), B. Alver et al., Phys. Rev. C 81, 054905 (2010)

Glauber initial conditions:

due to symmetry, odd Fourier components vanish

higher Fourier components may occur

Fluctuating initial conditions: B. Alver, Talk at the Glasma Workshop, BNL, May 2010


42

Initial Fluctuations II

B. Alver et al., arXiv: 1007.5469

B. Alver et al., Phys. Rev. C 81, 054905 (2010), B. Alver et al., arXiv: 1007.5469H. Petersen et al., arXiv: 1008.0625

v3 not negligable small

• v3 is extensively studied

Calculating v3 using a viscous hydro model with initial conditions deformed

according to the eccentricities from a Glauber and a KLM (CGC) model


43

Why v3 deformations cannot be the whole story

ptrigT=3 – 4 GeV, passoc

T=1 – 2 GeV

What are the consequences of triangular flow?

Do we only see fluctuating initial conditions?What is the difference of v3 and the impact of hot spots?

Study of heavy quark jets needed

120°


- Correlation in Df1-Df2

Df1/2 120°- No correlation in D1-

D2B. Alver et al., Phys. Rev. C 81, 054905 (2010)

Shock front??

~ 120J. Ulery [STAR], Int. J. Mod. Phys. E 16, 2005 (2007)

Summary „Conical“ signal can be created (general effect):

by averaging over wakes created by jets in different events.There is a deflection of particles emitted due to collective

transverse flow.

Structure cannot directly be related to EoS, but is a measure for the flow

Quite insensitive to deposition mechanism, jet velocity (even

for subsonic jets), and system size

Necessary to study heavy-flavor tagged jets.

44

„Conical“ correlations could arise from multiple non-Mach sourcesMach cones have to occur in heavy-ion collisions if there is a

fluid


Conical Correlations in Heavy-Ion Collisions

Documents

Transcript of Conical Correlations in Heavy-Ion Collisions