Identified particle elliptic anisotropy in 200 GeV Au+Au collision

at RHIC-PHENIX

Shingo Sakai

　 Univ. of Tsukuba

for the PHENIX Collaboration

Introduction

ｘ

ｙ

p

ｘ

p ｙ

Initial spatial anisotropyMomentum space anisotropy

of particle emission

) ) 2( cos 2 ) cos( 2 1(2 1 0... φ v φ v Ndφ

dN

The azimuthal anisotropy of particle emission is sensitive

to the early stages of system evolution

Motivation

pK vvv 222 ・ 　　 at low pT

(<1.5GeV/c)pvv 22

How about heavier particle ?

Measure of deuteron + anti-deuteron in 200 GeV Au+Au collision at RHIC-PHENIX

2v

・　　　　　　 at pT 　 >2.5GeV/c 　　

Coalescence model

deuteron and anti-deuteron produce the coalescence of the individual nucleons

-Coalescence model-

2

23

3

23

3

)

p

pp

d

dd dp

NdEB

dp

NdE

pn

d

)2( pd pp

Quark Matter 2002

Anuj K. Purwar and Rickard du Rietz

Au+Au collision at sqrt(SNN)=200GeV

)2/(2)( 22 tp

td pvpv

Method

/22obsvv

)]) ( 2 cos[ 2 1() (

2 0obs obs

obsv Nd

dN

σ=<cos(2(m-real))> = {<cos(2(A-B))>}1/2

particle emission

2)2cos(

)2sin(tan 1

iii

iii

w

w

-Reaction plane method-Measure azimuthal angle of each particle respect to the reaction plane

Reaction

Plane

X

Y

Less non-flow contribution

HBT 、 jet 、 resonance decay

64 pmts in each BBC

PHENIX detector

Beam Beam Counter (BBC)||=3-4

3 units of rapidity away

from the mid-rapidity

DCPC1

PC3

TOF

Tracking

DC+PC1+PC3p,φ

PID ・・・ TOF

m2 = p2 {(TOF/L)2 -1}

BBC

Reaction plane distribution

BB

CN

[rad]

[rad]

2obs

20

BBCS [rad]

obs+

0 = (Ancos(2nobs) + Bnsin(2nobs)) An = -2/n*<sin(2nobs)> Bn = 2/n*<cos(2nobs)>

PID

π

K

mass^2 [(GeV/c^2)^2] mass^2 [(GeV/c^2)^2]

Momentum [GeV/C]d

P

Including background

dN/dφ distribution

dn/dφ of

background

(normalize N )

dn/dφ of

subtracted

background

2d+dbar v

Φ-Ψ

32 2 m 54 2 m

b

)))(2cos(21(: 20 fitvNfit

2.0<p<3.0 dn/dφ

Compare with theory

P(PHENIX preliminary)

d-coalescence model

d+dbar

systematic error

)(

)(0

22

2

lowvv

upvprotonb

b

assuming

2vＰＨＥＮＩＸ　Ｐｒｅｌｉｍｉｎａｒｙ

PID v 2v

dpK vvvv 2222 ・

　　 at low momentum

　　　　 (<1.5GeV/c)

deuteron (estimate)

p pi

ＰＨＥＮＩＸ　Ｐｒｅｌｉｍｉｎａｒｙ2

(*) P.Huovinen, P.F.Kolb, U.W.Heinz, P.V.Ruuskanen and S.A.Voloshin, Phys. Lett. B503, 58 (2001)

Summary

・ deuteron + anti-deuteron (d+dbar)elliptic anisotropy are measured respect to the reaction plane

・ of d+dbar is estimated taking into account background

・　　　　　　　　　　　　 at low momentum (<1.5 GeV/c)　　　　　　　　・ Coalescence model & hydro model is comparable within error bar (sys.+stat.)

2v

dv2

dpK vvvv 2222

Coalescence model(2)

))cos()2(21(

))cos(21())cos(21(

)()(

2

2

nv

nvnv

d

dN

d

dN

pn

pn

dn

pd

)2/(2)( 22 tproton

tdeuteron pvpv

(1.0<p(GeV/c)<2.0) (2.0<p(GeV/c)<3.0)

(3.0<p(GeV/c)<4.0)

d+dbar

Gaussian+exp fit

< selection>

Quality 31 || 63

TOF-Track matching cut < 2 σ

PC3-Track matching cut < 2 σ

TOF E loss > 0.0014Β^(-5/3)

|Mass^2|<1.5σ(p)

32 2 m 54 2 m

dn/dφ of

background

(normalize N )

dn/dφ of

subtracted

background

2d,dbar v

dn/dφ

Φ-Ψ

b

)))(2cos(21(: 20 fitvNfit

1.0<p<2.0

dN/dφ distribution(1)

dn/dφ of

background

(normalize N )

dn/dφ of

subtracted

background

2d+dbar v

Φ-Ψ

dn/dφ

32 2 m 54 2 m

b)))(2cos(21(: 20 fitvNfit

3.0<p<4.0

dN/dφ distribution(2)

0-5%

5-10%

10-20%

BBC

Central arm

beam

Resolution

))(cos( truemeasurednCan’t measure

2))(cos(

))(cos())(cos(

))()((cos

))(cos(

trueA

trueBtrueA

trueBtrueA

BA

n

nn

n

n

Reaction plane resolutionReaction plane sub-event

(divide one event)

B2

Quark Matter 2002

Anuj K. Purwar and Rickard du Rietz

PID v2

Lambda

dpK vvvvv 22222 )( ・

　　 at low momentum

　　　　 (<1.5GeV/c)

dv2・ doesn’t saturate

(p<3.0 GeV/c)

π+&K+ (PHENIX preliminary)

p (PHENIX preliminary)

d+dbar

ＰＨＥＮＩＸ　Ｐｒｅｌｉｍｉｎａｒｙ

(C. Adler et al. Phys. Rev. Lett. 89, 132301 (2002))

PID v 2

dpK vvvv 2222 ・

　　 at low momentum

　　　　 (<1.5GeV/c)

dv2・ doesn’t saturate

(p<3.0 GeV/c)

2v

ＰＨＥＮＩＸ　Ｐｒｅｌｉｍｉｎａｒｙ