Measurements of , K and proton v2 and v4 in 200GeV Au+Au collisions

by the PHENIX experiment Shengli HuangShengli Huang

Vanderbilt University

for the PHENIX Collaborationfor the PHENIX Collaboration

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Observables and MotivationAnalysis methodsResults and DiscussionConclusions

Outline:

Anisotropic flow v2 and v4

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1

2

3

3

cos),(21dd

d

2

1

pd

d

nrTn

TT

nypvypp

NNE

rn nv cos

x

y

beam

reaction plane

Peter Kolb, PRC 68, 031902

Azimuthal correlation with the reaction plane Built up in the early stage and self-quenched, therefore supply the early information of matter generated in the collision

Spatial space asymmetry momentum space asymmetry

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NCQ ScalingPHENIX, PRL. 99, 052301 (2007)

Baryon and meson elliptic flow follow the number of constituent quark(NCQ) scaling as a function of KET at low KET.

NCQ scaling will break at intermediate pT if we assume that is mainly from the recombination of TS partons but proton is mainly from TTS and TSS .

NCQ scaling indicates the coalescence of the thermal parton

How about the higher order anisotropic flow such as v4?

Can we test this scaling break at high pT?

Hwa &&Yang arXiv:0801.2183[nucl-th]

04/21/23 SL Huang SQM08 5

Color Charge dependence

2 L<q>

CE s ^

4

9~

Eq

Eg

1.Gluon will lose more energy by gluonradiation in medium

2.The contribution from gluon jet fragmentationis different for pion, kaon(KS) and proton. The measurements of pion, kaon and proton and their anti-particles’ v2 will help us to study the color charge effect on energy loss

S. Wicks et al,Nucl.Phys.A784:426-442,2007S. Albino, B.A. Kniehl, G. Kramer, NPB 725 (2005) 181

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Star Preliminary

V4/(v2)2 ratio

v4 /v22 is a probe of ideal

hydro behavior and related to the degree of thermalization!

Peter Kolb, PRC 68, 031902(2003);R.S.Bhalerao et.al PLB 627,49(2005); Borghini and Ollitrault,PLB642,227(2006)

The identified particles v4/v2

2 ratio should provide more detailed information than that of charged hadron

Y.T. Bai QM06

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TOFw and Aerogel Detectors

1. TOFw intrinsic timing resolution is ~ 75ps2. /K can be separated to 2.8 GeV/c and K/p can be separated to 4.5 GeV/c3. Together with Aerogel detector(ACC), we can identify the K to pT~4 GeV/c and , p to 7 GeV/c

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RxNP:Two sets of plastic scintillators positioned on either side of the collision vertex 12 segments in 2 segments in 1.0 < || < 1.5 1.5 < || < 2.8

BBC: 3.1<||<3.9

Both detectors are away from mid-rapidity. Smaller non-flow effect on the reaction plane measurements

New RxNP detector resolution is around 74% at mid-centrality

Reaction plane Measurements

Sqr

t(2*

cos(

2*(

N-

S)))

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Identified particles elliptic flow

1. The proton’s v2 approaches to pion’s v2 as pT increases. It indicates the baryron production smoothly transits from TTT->TTS->TSS->SSS

2. The kaon’s v2 is similar to the pion’s v2 as a function of KET.

3. If particles production is dominated by jet fragmentation as pT~6GeV/c, the data indicates that the gluon will lose similar energy as light quark

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NCQ Scaling

The NCQ scaling is broken as KET/nq>1GeV. It is consistent with theorycalculation by assuming that the pion is from TS recombination but the proton is from TTS or TSS recombination at intermediate pT

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The v4 follows the KET scaling well for KET < 1 GeV

The number of constituent quark scaling holds for v4 when KET/nq < 1GeV. This confirms that matter with partonic degrees of freedom has been generated at RHIC

KET Scaling of v4

A.Taranenko

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V4/(v2)2 ratio

The ratio of v4/(v2)2 is close to 0.9 for the , K and p

Mesons and baryons have similar v4/(v2)2 ratio

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) (pv

) (pv

3

1

3

1

) (3pv

) (3pv

) (pv

) (pv

2

1

4

1

) (2pv

) (2pv

T2

q2,

Tq4,

T2

B2,

B4,

T2

q2,

Tq4,

T2

M2,

M4,

T

T

Meson

Baryon

How to Coalesce?Simple co-mover model at low pT

Meson

Baryon

L.W. Chen, C.M. Ko nucl-th 0602025

9.05.0) (3pv

) (3pv

) (2pv

) (2pv

T2

B2,

B4,

T2

M2,

M4, TT

Not only at intermediate pT region, even at low pT region, the particle is coalesced by the partons with different momentum

baryon(TTS)

Recombination at Intermediate pT

thermal

shower

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Conclusions

1. The number of constituent quark scaling has been observedfor v4 for KET/nq < 1 GeV. Mesons and baryons have similar v4/(v2)2 ratio which is close to 0.9

2. The proton’s v2 approaches to the pion’s v2 at pT~6GeV/c. And the kaon’s v2 is similar with pion’s v2 as a function of KET.

3. The NCQ scaling is broken at KET/nq~1GeV