1. Shengli Huang Vanderbilt University for the PHENIX Collaboration
Measurements of , K and proton v2 and v4 in 200GeV Au+Au collisions by the PHENIX experiment
Shengli Huang
Vanderbilt University
for the PHENIX Collaboration

2. Observables and Motivation Analysis methods Results and Discussion
Outline:
Observables and Motivation
Analysis methods
Results and Discussion
Conclusions
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S.L. Huang SQM08

3. Anisotropic flow v2 and v4x y
beam
reaction plane
Peter Kolb, PRC 68,
Spatial space asymmetry
momentum space asymmetry
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
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4. NCQ Scaling
PHENIX, PRL. 99, (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: [nucl-th]
SL Huang SQM08
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5. L <q> C E a  D Color Charge dependence2 L
<q> C E s a  D ^
1.Gluon will lose more energy by gluon
radiation in medium
2.The contribution from gluon jet fragmentation
is 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: ,2007
S. Albino, B.A. Kniehl, G. Kramer, NPB 725 (2005) 181
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6. V4/(v2)2 ratio v4 /v22 is a probe of ideal
Star Preliminary
v4 /v22 is a probe of ideal
hydro behavior and related to
the degree of thermalization!
Peter Kolb, PRC 68, (2003);
R.S.Bhalerao et.al PLB 627,49(2005);
Borghini and Ollitrault,PLB642,227
(2006)
The identified particles
v4/v22 ratio should provide more
detailed information than
that of charged hadron
Y.T. Bai QM06
S.L. Huang SQM08
2019/4/27

7. TOFw and Aerogel Detectors
M2 unit need change
TOFw intrinsic timing resolution is ~ 75ps
/K can be separated to 2.8 GeV/c and K/p can be separated
to 4.5 GeV/c
3. 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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8. Reaction plane Measurements
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
Sqrt(2*cos(2*(N-S)))
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9. Identified particles elliptic flow
The proton’s v2 approaches to pion’s v2 as pT increases. It indicates the baryron production smoothly transits from TTT->TTS->TSS->SSS
The kaon’s v2 is similar to the pion’s v2 as a function of KET.
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
SL Huang QM08
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10. NCQ Scaling
The NCQ scaling is broken as KET/nq>1GeV. It is consistent with theory
calculation by assuming that the pion is from TS recombination but
the proton is from TTS or TSS recombination at intermediate pT
SL Huang QM08
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11. KET Scaling of v4
A.Taranenko
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
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12. 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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13. How to Coalesce?
Simple co-mover model at low pT
baryon(TTS)
Recombination at Intermediate pT
Meson
Baryon
Meson
Baryon
thermal
L.W. Chen, C.M. Ko nucl-th
shower
Not only at intermediate pT region, even at low pT region, the particle is coalesced by the partons with different momentum
SL Huang QM08
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14. Conclusions
1. The number of constituent quark scaling has been observed
for 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
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