High pT identified charged hadron v2 and v4 in 200GeV AuAu collisions by

the PHENIX experiment Shengli HuangShengli Huang

Vanderbilt University

for the PHENIX Collaborationfor the PHENIX Collaboration

23/4/19 S.L. Huang QM08 2

Observables and MotivationAnalysis methodsResults and DiscussionConclusions

Outline:

Anisotropic flow v2 and v4

23/4/19 S.L. Huang QM08 3

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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Partonic FlowPHENIX, PRL. 99, 052301 (2007)

Baryon and meson elliptic flow follow the number of constituent quark scaling as a function of KET. This indicates that partonic flow builds up at RHIC

Where is the break point where the hydro interfaces with jet fragmentationThe medium density and strength of interactions The dynamic range of theglobal partonic flow

How about the higher order anisotropic flow such as v4?

baryon

meson

0mmKE TT

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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, 031902R.S.Bhalerao et.al PLB 627,49; Borghini and Ollitrault, PLB642,227

Hydro dynamics predicts v4 /v2

2 ~0.5

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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How to Coalesce?

) (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

a) Similar momentum space

)) (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

b) Different momentum space

Meson

Baryon

Meson

Baryon

The measurement of meson and baron v4 /v22 ratio

will allow us to extract the partonic v4,q /v2,q2 ratio

To test whether the partons in different momentum space also can recombine with each other

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

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PHENIX in Run 7

Run 7: ~4.5B events and around 50% have been used A new Time of Flight detector (TOFw) has been installed in the west arm of PHENIX A new reaction plane detector (RxNP) has been installed in the 38 cm < |z| < 42 cm alone the beam

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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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Mass ordering of v2 and v4

V4 has been measured as a function of pT in different centrality bins for the , K and p

Mass ordering has been observed for both v2 and v4

Consistent with the hydrodynamics

Poster 166 A.Taranenko

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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 < 1 GeV. This confirms that matter with partonic degrees of freedom has been generated at RHIC

KET Scaling of v4

P166 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

What can we extract from this measurement?

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Partonic Thermalization !

)) (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 2

1

) (pv

) (pv

T2

q2,

Tq4,

8.1

1. Parton v4,q/(v2,q)2~0.5 Perfect Partonic Liquid!2. Partons in different momentum space also can recombine with each other3. Interact more frequently and strongly with each other

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Charged v2

Charged v2 can be measured to6 GeV/c.

The results are consistent with 0 results in the overlap pT region.

All v2 start to drop at pT ~ 2.5 GeV/c in the different centrality bins!

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Kaon and Proton v2

Kaon v2 can be measured to 4 GeV/c and protons v2 can be measured to 6 GeV/c

Proton v2 starts to drop at pT ~ 4 GeV/c

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Break Point?

In the centrality of 20~60%, the , K and p KET scaling seemly begins to break at KET/nq ~ 1 GeVMore statistics are required for the further investigation

A factor 2 of Run 7 data will come after QM08

KET/nq(GeV) KET/nq(GeV)

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Conclusions

New time of flight detector(TOFw) of PHENIX runs successfullyin Run 7 with 75 ps intrinsic timing resolution. With new TOFw and RxNP detectors, we can measure the identified charged hadrons v2 to pT~6 GeV/c and v4 to 3 GeV/c

The number of constituent quark scaling has been observedfor v4 for KET/nq < 1 GeV. Mesons and bayrons have similar v4/(v2)2 ratio which is close to 0.9The parton v4,q/(v2,q)2 ~ 0.5 : perfect partonic liquid Partonic ThermalizationThe number of constituent quark scaling seemly begins to break for v2 as KET/nq~1GeV at 20~60% centrality:a)The interface between hydro and jet fragmentationb)Quantitative information about density and interaction strength