Two particle correlations with respect tohigher harmonic plane in Au+Au 200 GeV
collisions 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	

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Outline	
1. Introduction"
üHigher harmonic event plane(Φn) & flow(vn)"üBackgrounds from vn in correlations"üvn subtracted correlations"

2. Physics Motivation"
3. Analysis Overview"
4. Results"üΦ2 & Φ3 dependence "5. Summary	26	  Mar.	  2012	

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Higher harmonic event plane & flow	• Previous picture; Assumed a “reaction plane” definedby impact parameter vector and beam axis vector"• Recent picture; Higher harmonic deformation due tofluctuations of collision geometry"ü Deformation transferred to momentum space bycollective expansion → higher harmonic flow(vn)	
Φ3	
Φ2	
Φ4	dNAzimuth.
∝ 1 + 2v2 cos 2(φ − Φ2 ) + 2v3 cos 3(φ − Φ3 ) + 2v4 [Φ4 ] cos 4(φ − Φ4 )distribution	 dφ26	  Mar.	  2012	

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Backgrounds from vn in 2 particle correlations	Jet(∆φ) = CF (∆φ) − b0 F low(∆φ)
Phys. Rev. C 80, 064912 (2009)	

Phys. Rev. C 78, 014901 (2008)	

2< pTasso < pTtrig GeV/C	

trig asso
b0 2vRidge	
v3 cos 3∆φv2 subtracted	
3
n=3	

○:p+p
●: Au+Au	Jet(∆φ) = C2 (∆φ) − b0 F low(∆φ)
n=3	

trig asso∼ b0 2vn b v2v
trig cosasson∆φ Shoulder	nv
cos 3∆φ033

あああああああああああああRidge : near side long rangeΔη correlations	Shoulder: double hump at away sideof Δφ correlations (also long in Δη)	• Backgrounds from vn " ∼ b0 2vn

trig asso
vn cos n∆φü vn (especially v3) subtraction reduce “Ridge” and “Shoulder”"
あああああああああああああああああああü vn subtractions help to see more “real” correlation shape	
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vn subtracted correlations	work in progress	V2	  V	  &4(Φ	  V42(Φ)	  subtracted	
V2	  &)	  Z2YAM	  subtracted	

V2,	  V3	  &	  V4(Φ4)	  ZYAM	  subtracted	

• Shoulder is described by vn in central collisions	• Shoulder is still seen in mid-central collisions "26	  Mar.	  2012	

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Physics Motivations	• vn subtracted correlations still show doublehump structure in ways side in mid-centralcollisions"ü Average of jets flying to various direction in bulk "• Detailed survey of away side peaks"ü Two particle correlations with trigger selection relativeto Φ2 & Φ3	

- Modification of away side w.r.t. Φ2 & Φ3	

- Difference➇	between Φ2 & Φ3	➆	➅	➄	➄	➍	➍	➌	➊	➋	➇	➆	➅	➌	➋	➊	26	  Mar.	  2012	

物理学会年次大会	  6/10	Analysis Overview	
RXN in: 1.5<|η|<2.8& out: 1.0<|η|<1.5

CNT: |η|<0.35

PHENIXdN/dη	!3

MPC: 3.1<|η|<3.7
BBC: 3.0<|η|<3.9!2

ZDC/SMD!4
-5• vn measurements"05

ηü Forward Event Plane(RXN) - Charged Hadrons in mid-rapidity"- To exclude autocorrelations by jet"

• Selection of Trigger Directions"ü Forward Event Plane(RXN)-Charged Hadron Trigger in mid-rapidity"• 2 particle charged hadron correlations in azimuth"ü Mid-rapidity Trigger – Mid-rapidity Associate, pT : 2-4 & 1-2 [GeV/c] "• Subtract vn modulated backgrounds by ZYAM Method	
26	  Mar.	  2012	

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Φ2 dependent correlations 	out-­‐of-­‐plane	  	  trigger	  case	  Trig.	  

in-­‐plane	  	  trigger	  case	  200GeV	  Au+Au	  -­‐>	  h-­‐h,	  20-­‐50%	  (pTTrig=2~4,	  pTAsso=1~2GeV/c)	  v2,	  v3	  &	  v4{Φ4}	  subtrac=on	  PHENIX	  work	  in	  progress	  Trigger	  angle	  selec=on	  w.r.t.	  
Φ2	  for	  	  le?(up)	  /	  right(down)	  Trig.	  

Φ2	  R.P.	  

Φ2	  R.P.	  

Flow	  subtracted	  yield	  is	  shown	  radially	  with	  base	  line.	  

Trig.	  Trig.	  shi<	  to	  out-­‐of-­‐plane	  shi<	  to	  in-­‐plane	  • Two competitive effects"ü Away-side peak shift to in/out of plane with in/outof plane trigger"26	  Mar.	  2012	

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:	  C2(data)	  :	  vn	  backgrounds	In-­‐plane	ü Φ2 dominated by almond shape"ü Φ3 dominated by fluctuations"ü Would be related to differences "▪▫
-­‐-­‐
Correla=on	  Func=ons	

• Subtraction shows noevident dependence"• Difference b/w Φ2 & Φ3"out-­‐of-­‐plane	Φ3 dependence before vn subtractions	26	  Mar.	  2012	

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Summary	• Measured two particle correlations with trigger
selection relative to Φ2 & Φ3	• Φ2 dependent correlations show two competitiveeffects"ü Away-side peak shift to in/out of plane with in/out ofplane trigger"• Φ3 harmonic plane dependence wouldnʼt be seen"ü Φ2 dominated by almond shape"ü Φ3 dominated by fluctuations"26	  Mar.	  2012	

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Back Up Slides	

26	  Mar.	  2012	

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Charged hadron vn Centrality and pT dependences	PRL.107.252301	  (ppg132)	

charged	  par=cle	  vn	  :	  |η|<0.35	  event	  plane	  Φn	  :	  |η|=1.0~2.8	  • v3 is comparable to v2 at 0~10%"• v2 rises up when centrality goes up, but v3 hardly does"• v4{Φ4} ~ 2 x v4{Φ2}"26	  Mar.	  2012	

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v3v2

a much lower v3 than obtained with Glauber MC calcuwith pT for
Degeneracy
amongmodelslations. Consequently,
our measurementof vdisentangled
3 f!3 g helps tomore central
rom centralbyv	
3
xpected in0.3 (a) p = 0.75-1.0 GeV/c
PRL.107.252301	  (ppg132)	
(b) pT = 1.75-2.0 GeV/c
T
B. Alver et. al., PRC82, 034913(2010)."27,28]. ThePHENIX(Event	  Plane	  Method)	
B. Schenke et. al., PRL106, 042301(2011).
KLN + 4πη/s = 2ficance, also
H. Petersen et. al., PRC82, 041901(2010)."0.2
Glauber + 4πη/s = 1 (1)V2	dependent,
0.1
most central
ber calcula00100200300
0100200300ized ‘‘trian(c) pT = 0.75-1.0 GeV/c(d) pT = 1.75-2.0 GeV/c0.1s (b) and (d)UrQMD + 4πη/s = 0
Glauber + 4πη/s = 1 (2)results from
V3	0.05
rality trends
ent with thepT below
00100

200

300

0100200300

NpartNparte of v2 f!2 gons, demon• v3 seems
to preferviscosity"
FIG. 3 (coloronline).low
Comparisonof [(a) and (b)] v2 f!2 g vside and also(d)]v3 f!
Npart and [(c) and3 g vs Npart measurements andüGlauber+4πη/s=1works
better"of different
theoretical predictions (see text): ‘‘MC-KLN þ 4!"=s ¼ 2’’=2 failed"er et al. [27]ü CGC-KLN+4πη/sand ‘‘Glauber þ 4!"=s¼ 1 (1)’’ [27]; ‘‘Glauber þ 4!"=s ¼ 1
þ 1 dimen(2)’’ [32]; and‘‘UrQMD’’[29]. Shaded(magenta) around• vn provides
moreconstraints
toareashydrodynamics
erent initial
the data points indicate sizes of systematic uncertainties.

calculations"26	  Mar.	  2012	

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Fourier decomposition of flow subtracted
correlations	26	  Mar.	  2012	

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Φ2 dependence with v2 & v4(Φ2) subtraction	➊➇	➋➆	

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26	  Mar.	  2012	

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Trigger dependence relative to event plane	 200GeV	  Au+Au	  -­‐>	  h-­‐h,	  20-­‐50%	  	  	  (pTTrig=2~4,	  pTAsso=1~2GeV/c)	  v2,v4{Φ2}	  only	  subtracJon	  PHENIX	  preliminary	  Trigger	  angle	  selecJon	  w.r.t.	  
Φ2	  separately	  for	  le<(up)	  /	  right(down)	  out-­‐of-­‐plane	  	  trigger	  case	  Trig.	  

Trigger	  angle	  selected	  2-­‐part.	  
corr.	  data	  are	  ploLed	  in	  polar	  coordinate	  by	  rotaJng	  Φ2	  R.P.	  
angle	  as	  X-­‐axis.	  	  Flow	  subtracted	  yield	  is	  shown	  radially	  with	  base	  line.	  

RHIC-­‐PHENIX	  Flow	  plenary	  S.E.	  

Trig.	  in-­‐plane	  	  trigger	  case	  Φ2	  R.P.	  

Φ2	  R.P.	  

Trig.	  Trig.	  surface	  dominance	  penetraJon	  dominance	  Two	  compeJng	  processes	  seen	  26	  Mar.	  2012	

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Φ2 dependence with v2 & v3 & v4 subtraction	

200GeV	  Au+Au	  -­‐>	  h-­‐h,	  20-­‐50%	  	  	  (pTTrig=2~4,	  pTAsso=1~2GeV/c)	  v2,v3,v4{Φ4}	  subtracJon	  1/NtrigdNpair/dΔφ	PHENIX Work in progress	➊➇	➋➆	➌➅	

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out-­‐of-­‐plane	䚀In-­‐plane	Δφ [rad]	

26	  Mar.	  2012	

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