shengli huang vanderbilt university for the phenix collaboration
DESCRIPTION
Measurements of , K and proton v 2 and v 4 in 200GeV Au+Au collisions by the PHENIX experiment. Shengli Huang Vanderbilt University for the PHENIX Collaboration. Outline:. Observables and Motivation Analysis methods Results and Discussion Conclusions. reaction plane. beam. x. y. - PowerPoint PPT PresentationTRANSCRIPT
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
23/4/21 S.L. Huang SQM08 2
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