Background introduction Model introduction Analysis method Results and discussions Conclusions

Collaborators: S. Zhang, Y. G. Ma, H. Z. Huang, X. Z, Cai, J. H. Chen, Z. J. He, J. L. Long, W. Q. Shen, X. H. Shi, J. X. Zuo.

Shanghai Institute of Applied Physics   

Two- and Three-particle Correlations in a Partonic Transport Model

Guo-Liang Ma   

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Di-hadron correlations

Soft associated Soft associated particlesparticles →→ enhancementenhancement

Hard associated Hard associated particles particles →→ suppressionsuppression

Associated particlesOn away side:

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pT(assoc) > 2 GeV/c

pT(assoc) > 0.15 GeV/c

4 <

p T(t

rig)

< 6

GeV

/c

Mach-like Structures

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Mach cone shock waves Mach cone shock waves

NPA 750, 121 (2005) Stöeckerhep-ph/0411315, hep-ph/0602183 Casalderrey-SolanaPLB 618, 123 (2005) J. RuppertPRC 73, 011901(R) (2006) T. RenkPRL 97, 062301(2006) A. K. Chaudhuri

PRC 72, 064910 (2005) Armesto

Correlation of Jet with flowing medium Correlation of Jet with flowing medium

Gluon radiations (Cherenkov or Bremsstrahlung)

Gluon radiations (Cherenkov or Bremsstrahlung)

PRL 96, 172302 (2006) Koch, Majumder, X.-N. WangPLB 630, 78 (2005) I. VitevNPA 767, 233 (2006) I.M. Dremin

Possible interpretations of Mach-like structuresΘemission= arccos (cs/c)

Θemission= arccos (1/n(p))

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AMPT model

(1) Default AMPT Model (2) Melting AMPT Model

a multi-phase transport model (by C. M. Ko and Z. W. Lin et al.)

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(1) Get raw correlation signal in same event.

(2)Get corresponding background by mixing events in same centrality.

(3)Get correlation by removing background with ZYAM method

(PHENIX Collaboration PRL 97, 052301

(2006)).

Mixing-event Technique

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Background Subtracted signal

AMPT model

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

▲ melting version with hadronic rescattering (10mb)

● melting version without hadronic rescattering (10mb)

■ STAR data 0-5% (4-6)x(0.15-4)GeV/c

Mach-like structure is born in strong parton cascade process, and furthermore developed in hadronic rescattering process.

The problem of excessive correlation magnitude.

correlationscorrelations from AMPT from AMPT((3<pT

trigger<6GeV/c ,0.15<pTassoc<3GeV/c)

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

■ STAR data 0-5% (4-6)x(0.15-4)GeV/c

◆ default version with hadronic rescattering

★ default version without hadronic rescattering

No splitting is seen on away side under the soft pT cut in default version (only with hadronic resacttering )!

correlationscorrelations from AMPT from AMPT((3<pT

trigger<6GeV/c ,0.15<pTassoc<3GeV/c)

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

More information from 3-particle correlation --- deflected jets or Mach cone shock waves?

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① deflected-jets

Mediumaway

near

② Mach cone shock waves:

away

near

Medium

Δ2

Δ1π

π

0

0

Δ2

Δ1π

π

0

0

Three-particle correlations in AMPT

mix-event technique background subtracted

3-particle correlation signal

((2.5

<pTtri

gger <

4GeV

/c ,1

<

p Tas

soc <2

.5GeV

/c)

(10)nucl-th/0608050, G. L. Ma et al.

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2 4 6 8 10 120.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1.0

1.1

1.2

AMPT: PT

trig 2.5-4(GeV/c),PT

associated 1-3.(GeV/c)

PHENIX data: PT

trig 2.5-4(GeV/c),PT

associated 2-3(GeV/c)

split

ing p

ara

mete

r D

(ra

d)

impact parameter b (fm)

■ PHENIX data (nucl-ex/0510019 )□ parton cascade + hadronic rescattering○ hadronic rescattering

Parton cascade effect on 2- and 3- particle correlations

1) Hadronic rescattering mechanism alone can not give big enough splitting parameters and correlation areas.

2) Parton cascade mechanism is essential for describing the splitting amplitude of experimental Mach-like structure.

3) Large energy loss in dense partonic medium.

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parton cascade + hadronic rescattering hadronic rescattering alone

Au+Au 200GeV (0-10%)

Partonic Mach-like Shock Waves ?

(12)(12)nucl-th/0610088, G. L. Ma et al.

pT dependences of Mach-like structures

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ppTT-dependent Mach-like -dependent Mach-like

shock wavesshock waves

See S. Zhang’s poster, for the detail of pT and η dependences of Mach-like structures (49, section 2) .

Conclusions1) Partonic Mach-like shock waves are born in the str

ong dynamical parton cascade and further developed in hadronic rescattering process. The problem of excessive correlation magnitude is still not solved in current AMPT model.

2) Hadronic rescattering mechanism alone can produce similar correlations, but it can not give big enough splitting parameters and correlation areas.

3) The partonic Mach-like shock waves are centrality-dependent ,pT-dependent within the AMPT model.

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Thanks for your attentions!

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