Two particle correlations with respect to higher harmonic plane in Au+Au 200 GeVcollisions at RHIC-PHENIX
Takahito Todoroki for the PHENIX Collaboration
Univ. of Tsukuba, RIKEN Nishina Center
JPS Annual Meeting 2012, Mar. 24-27th
@Kwansei Gakuin
26 Mar. 2012 物理学会年次大会 1/10
Outline
1. IntroductionHigher harmonic event plane(n) & flow(vn)
Backgrounds from vn in correlations
vn subtracted correlations
2. Physics Motivation
3. Analysis Overview
4. Resultsdependence
• Summary
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• Previous picture; Assumed a “reaction plane” defined by impact parameter vector and beam axis vector
• Recent picture; Higher harmonic deformation due to fluctuations of collision geometryDeformation transferred to momentum space by
collective expansion → higher harmonic flow(vn)
Higher harmonic event plane & flow
Azimuth. distribution
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Backgrounds from vn in 2 particle correlations
• Backgrounds from vn
vn (especially v3) subtraction reduce “Ridge” and “Shoulder”
vn subtractions help to see more “real” correlation shape
26 Mar. 2012
Ridge
2< pTasso < pT
trig GeV/C
Phys. Rev. C 80, 064912 (2009)
Ridge : near side long range correlations
Shoulder: double hump at away side of correlations (also long in )
Phys. Rev. C 78, 014901 (2008)○:p+p●: Au+Au
Shoulder
v2 subtracted
n=3 n=3
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vn subtracted correlations
• Shoulder is described by vn in central collisions
• Shoulder is still seen in mid-central collisions
26 Mar. 2012
work in progress
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V2 & V4() subtractedV2 & V4() ZYAM subtracted
V2, V3 & V4() ZYAM subtracted
5/10
Physics Motivations
• vn subtracted correlations still show double-hump structure in ways side in mid-central collisionsAverage of jets flying to various direction in bulk
• Detailed survey of away side peaksTwo particle correlations with trigger selection relative
to &
- Modification of away side w.r.t. &
- Difference between &
26 Mar. 2012 物理学会年次大会
➊➋
➌
➍
➄
➅➆
➇
➊➋
➌
➍
➄
➅
➆➇
6/10
Analysis Overview
• vn measurements Forward Event Plane(RXN) - Charged Hadrons in mid-rapidity
- To exclude autocorrelations by jet
• Selection of Trigger Directions Forward Event Plane(RXN)-Charged Hadron Trigger in mid-rapidity
• 2 particle charged hadron correlations in azimuth Mid-rapidity Trigger – Mid-rapidity Associate, pT : 2-4 & 1-2 [GeV/c]
• Subtract vn modulated backgrounds by ZYAM Method
26 Mar. 2012
0 5-5
ZDC/SMD
dN/d
RXN in: 1.5<||<2.8 & out: 1.0<||<1.5
MPC: 3.1<||<3.7
BBC: 3.0<||<3.9
CNT: ||<0.35
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PHENIX
7/10
dependent correlations
• Two competitive effectsAway-side peak shift to in/out of plane with in/out
of plane trigger26 Mar. 2012
2 R.P.
shift to in-planeshift to out-of-plane
2 R.P.
Trig.
Trig.
Trig.
Trig.
in-plane trigger case
out-of-plane trigger case
Flow subtracted yield is shown radially with base line.
Trigger angle selection w.r.t. 2 for left(up) / right(down)
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200GeV Au+Au -> h-h, 20-50% (pT
Trig=2~4, pTAsso=1~2GeV/c)
v2, v3 & v4{4} subtractionPHENIX work in progress
8/10
dependence before vn subtractions
• Subtraction shows no evident dependence
• Difference b/w &
dominated by almond shape
dominated by fluctuations
Would be related to differences
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out-
of-p
lane
In-p
lane
▪▫: C2(data)--: vn backgrounds
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Corr
elati
on F
uncti
ons
Summary• Measured two particle correlations with trigger
selection relative to &
• dependent correlations show two competitive effectsAway-side peak shift to in/out of plane with in/out of
plane trigger
• harmonic plane dependence wouldn’t be seen
dominated by almond shape
dominated by fluctuations
26 Mar. 2012 物理学会年次大会 10/10
• v3 is comparable to v2 at 0~10%
• v2 rises up when centrality goes up, but v3 hardly does
• v4{4} ~ 2 x v4{2}
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charged particle vn : ||<0.35event plane n : ||=1.0~2.8
PRL.107.252301 (ppg132)
Charged hadron vn Centrality and pT dependences
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Degeneracy among models disentangled by v3
• v3 seems to prefer low viscosity Glauber+s works better CGC-KLN+s failed
• vn provides more constraints to hydrodynamics calculations
26 Mar. 2012
V2
V3
PRL.107.252301 (ppg132)B. Alver et. al., PRC82, 034913(2010).B. Schenke et. al., PRL106, 042301(2011).H. Petersen et. al., PRC82, 041901(2010).
(Event Plane Method)
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Trigger dependence relative to event plane
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2 R.P.
penetration dominancesurface dominance
2 R.P.
Trig.
Trig.
Trig.
Trig.
Trigger angle selected 2-part. corr. data are plotted in polar coordinate by rotating 2 R.P. angle as X-axis.
in-plane trigger case
out-of-plane trigger case
Flow subtracted yield is shown radially with base line.
200GeV Au+Au -> h-h, 20-50% (pT
Trig=2~4, pTAsso=1~2GeV/c)
v2,v4{2} only subtractionPHENIX preliminary
Two competing processes seen
Trigger angle selection w.r.t. 2 separately for left(up) / right(down)
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RHIC-PHENIXFlow plenaryS.E.
17/10
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1/N
trigdN
pair/
d ➊➇ ➋➆ ➌➅ ➍➄
[rad]
out-of-plane In-plane
PHENIX Work in progress
200GeV Au+Au -> h-h, 20-50% (pT
Trig=2~4, pTAsso=1~2GeV/c)
v2,v3,v4{4} subtraction
dependence with v2 & v3 & v4subtraction
物理学会年次大会 18/10