Multi-particle correlation in a
multi-phase transport model

Shanghai Institute of Applied Physics, CAS
Ma Guo-Liang (馬國亮)
Collaborators: S. Zhang,Y. G. Ma, H. Z. Huang, X. Z, Cai, J. H. Chen,Outline• Introduction (Motivation and Model)• Result and discussion:• Mach-like structure• Ridge phenomenon• Conclusion2Jet production and di-hadroncorrelation
pTtrig>4 GeV/c, 2<pTassoc<4 GeV/c

Au+Au

hadronsqq3

Jet production and di-hadroncorrelation
pTtrig>4 GeV/c, 2<pTassoc<4 GeV/c

Au+Au

hadronsqq3

Jet production and di-hadroncorrelation
pTtrig>4 GeV/c, 2<pTassoc<4 GeV/c

Au+Au

hadronsqq3

Mach-like and ridge structures
Au+Au

Dd+Au

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Theoretical interpretations of Mach-like structure (1)Mach cone shock wave:

Casalderrey-Solana, Shuryak, Teaney, hep-ph/0411315
Chesler & Yaffe arXiv:0712.0050

Gubser, Pufu, Yarom
arXiv:0706.4307

Neufeld, arXiv: 0807.2996

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Theoretical interpretations of Mach-like structure (2)Cherenkov radiation:
Θemission= arccos (1/n(p))
PRL 96, 172302 (2006)
Koch, Majumder, X.-N. Wang
NPA 767, 233 (2006) I.M. Dremin

Correlation of Jet with flowing medium:
PRC 72, 064910 (2005) Armesto

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AMPT modela multi-phase transport model (by C. M. Ko and Z. W. Lin et al.)
PRC 72, 064901 (2005)(1) Default AMPT Model(2) Melting AMPT Model(1) initialcondition(2) partoncascade(3) hadronization(4) hadronic
rescattering
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Mixing-event Technique
Au+Au 200 GeV

Au+Au 200 GeV

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Δφ correlations from AMPT
(3<pTtrigger<6GeV/c ,0.15<pTassoc<3GeV/c)▲ melting version withhadronic rescattering (10mb)● melting version without
hadronic rescattering (10mb)■ STAR data
0-5% (4-6)x(0.15-4)GeV/c

PLB
641,362(2006)
PLB
641,362(2006)
G.G.
L. L.
MaMa
et etal.al.

 Mach-like structure is born instrong parton cascade
process, and furthermore
developed in hadronicrescattering process.
 The problem of excessive
correlation magnitude.
9Δφ correlations from AMPT
(3<pTtrigger<6GeV/c ,0.15<pTassoc<3GeV/c)
 No obvious splitting isseen on away side under
the soft pT cut in defaultversion (only withhadronic resacttering )!

■ STAR data
0-5% (4-6)x(0.15-4)GeV/c◆ default version withhadronic rescattering★ default version without
hadronic rescattering

PLB 641, 362 (2006) G. L. Ma et al.

10More information from 3-particle correlation--- deflected jet or Mach cone shock wave?

1. deflected-jet

2.Mach cone shock wave

near

near

MediumMediumaway

away

Δφ2Δφ2ππ000πΔφ10πΔφ111Three-particle correlations in AMPTPLB 647, 122 (2007) G. L. Ma et al.

(21< .5<p a pT t

T srigsogec< r

2. <4G5G eeV V//c c ,)mix-event techniquebackground subtracted
3-particle correlation signal

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Partonic Mach-like Shock Waves
t=0.5 fm/c

t=1.0 fm/c

t=1.5 fm/c

t=2.0 fm/c

t=4.0 fm/c

t=5.0 fm/c

exp. data

Au+Au 200GeV (0-10%)evolution-timeη/s ≈T

5nσ

Strong-coupling

nucl-th/0610088, G. L. Ma et al.
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“Ridge” observation
Additional near-side longrange corrl. in Δη (“ridgelike” corrl.) observed.
Dan Magestro, Hard Probes 2004,
STAR, nucl-ex/0509030 and P. Jacobs,nucl-ex/0503022

Au+Au, 0-5%

d+Au, 40-100%

3 < pT(trig) < 6 GeV
2 < pT(assoc) < pT(trig)

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Theoretical interpretations of ridge
1. Recombination model
Chiu and Hwa, PRC 72, 034903 (2005)

2. Longitudinal expansion of QGP
L.M. Satarov, H. Stöcker et al., PLB 627 (2005) 64

3. Collisional energy loss of heavy Q
Paul Romatschke, PRC 75, 014901 (2007)

4. Turbulent color field
A. Majumder, B. Muller et al., PRL 99, 042301 (2007)

5. Momentum kick model
C.Y. Wong Phys. Rev. C 76, 054908 (2007)15

Ridge correlation @ AMPT
2.5<pTtrig<6GeV/c,1.5<pTasso<2.5GeV/c, |η|<1.0

Au+Au 200GeV(0-10%)from Melting AMPT model:
the projected Δϕ distribution
in Au+Au 200 GeV(0-10%)

the projected Δη distribution
in Au+Au 200 GeV(0-10%)

p+p 200GeV
from Default AMPT model:
the projected Δϕ distribution
in p+p 200 GeV

the projected Δη distribution
in p+p 200 GeV
G. L. Ma et al., arXiv:0807.3987

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How the ‘ridge’ grows up?
t=0.5 fm/c

t=1.0 fm/c

t=1.5 fm/c

t=2.5 fm/c

slope = 0.085 ± 0.002 fm−1

t=3.0 fm/c

t=4.0 fm/c

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Longitudinal flow from parton cascade
NUFM Fit (PRC, 63, 014901(2000)) :(a nonuniform longitudinal flow model)

slope = 0.093 ± 0.003 fm−1

evolution-time (fm/c)

evolution-time (fm/c)

The ridge is attributed to the longitudinal flow due tostrong parton cascade.

(1)

(2)

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Conclusions• Mach-like shock wave is born in the strong parton••cascade and developed in hadronic rescattering.
Splitting amplitude of Mach-like structure can be
reproduced by a partonic cross section 10 mb
instead of 3 mb, which indicates a strongly coupling
matter at RHIC.
The longitudinal broadening of near side is due tothe longitudinal flow produced by strong partoncascade.
19Thank you!

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Back up21

Parton cascade effect on 2- and 3particle correlations
BRAHMS data (PRL 91 (2003) 072305 )□ parton cascade(10 mb) + hadronic rescattering○ hadronic rescattering■■ PHENIX data (nucl-ex/0510019 )□ parton cascade(10 mb) + hadronic rescattering○ hadronic rescattering

parton cascade(10 mb)+ hadronic rescattering

hadronic rescattering alone Hadronic rescattering mechanism
alone can not give big enoughsplitting parameters and correlation
areas.
 Parton cascade mechanism isessential for describing the splitting
amplitude of experimental Mach-likestructure.
 large energy loss in dense partonicmedium.

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