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

26 Mar. 2012 物理学会年次大会 2/10

• 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

26 Mar. 2012 物理学会年次大会 3/10

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

物理学会年次大会 4/10

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

物理学会年次大会

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

物理学会年次大会

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)

物理学会年次大会

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

26 Mar. 2012

out-

of-p

lane

In-p

lane

▪▫: C2(data)--: vn backgrounds

物理学会年次大会 9/10

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

Back Up Slides

26 Mar. 2012 物理学会年次大会 11/10

• 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}

26 Mar. 2012

charged particle vn : ||<0.35event plane n : ||=1.0~2.8

PRL.107.252301 (ppg132)

Charged hadron vn Centrality and pT dependences

物理学会年次大会 12/10

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)

物理学会年次大会 13/10

26 Mar. 2012 物理学会年次大会 14/10

QM2011, ATLAS

Fourier decomposition of flow subtracted correlations

26 Mar. 2012 物理学会年次大会 15/10

dependence with v2 & v4 subtraction

26 Mar. 2012

➊➇ ➋➆ ➌➅ ➍➄

物理学会年次大会 16/10

Trigger dependence relative to event plane

26 Mar. 2012

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)

物理学会年次大会

RHIC-PHENIXFlow plenaryS.E.

17/10

26 Mar. 2012

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

26 Mar. 2012 物理学会年次大会 19/10