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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
23/4/19 SL Huang QM08 4
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
23/4/19 S.L. Huang QM08 5
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
23/4/19 SL Huang QM08 6
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
23/4/19 SL Huang QM08 7
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
23/4/19 SL Huang QM08 8
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
23/4/19 SL Huang QM08 9
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)))
23/4/19 S.L. Huang QM08 10
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
23/4/19 S.L. Huang QM08 11
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
23/4/19 S.L. Huang QM08 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
What can we extract from this measurement?
23/4/19 S.L. Huang QM08 13
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
23/4/19 S.L. Huang QM08 14
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!
23/4/19 SL Huang QM08 15
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
23/4/19 SL Huang QM08 16
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)
23/4/19 SL Huang QM08 17
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