three particle correlation study using run 4 data (auau 200 gev)

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Three Particle Correlation Study using Run 4 data (AuAu

200 GeV)

Vasily Dzhordzhadze, Jim Thomas

CP Group Teleconference, BNL

September 16, 2008

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Jim’s code : a fast analysis of large statistics using STAR

farm -> results within a day, plus ability to write in a

format for next step analysis used by Vasily’s programs

Vasily’s code : 3 particle correlation study using

Jim’soutput files : ~2-3 hours + few minutes for

correlationplots -> ability in 24 hours have a new result !

Statistics analysed: 14 M AuAu 200 GeV, Run 4

|Zvertex| <30. dca<3.0 0.15<Pt<2.0 15<Nhits<45 nHitPoints/nHitsPossible>0.52

Introduction

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Outut structure written by Jim’s program:

xM[ncharge][nharmonic][nsubgroup][nEta]yM[ncharge][nharmonic][nsubgroup][nEta]Ncharge = 2 nharmonics = 3nsubgroups = 2 nEta = 11 -1.1 <

< 1.1

Event number, CentralityxM[i][0][j][k] – statistic xM[i][1][j][k] – cos() xM[i][2][j][k] - cos(2)

yM[i][0][j][k] – Pt yM[i][1][j][k] – sin() yM[i][2][j][k] - sin(2)

Vectors Used in the Analysis

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Three particle correlations -> Correlations between

different bins of .

aiaj = -<cos(i+ j – 2*EP)>/<cos2(aEP - b

EP)>

i = (n n )/n j = (m m)/m n, m number of tracks

in bins of i and j.

1.Particles ordered by angle (as comes from dst)

2.Particles ordered by random generator (Ilya)3.Particles ordered by random generator (Jim)

Three Particle Correlations

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Run 4, AuAu 200 GeV, 9.5 M (Ilya)

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Run 4, AuAu 200 GeV, 14M (Jim, no Rndm case (1))

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Run 4, AuAu 200 GeV, 14M (track rndm, case(2 Ilya))

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a-a- and a+a+ parameters for centrality bin 9

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Run 4, AuAu 200 GeV, ~10M (track rndm, case(2 Ilya))

10 x

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Run 4, AuAu 200 GeV, ~10M (track rndm, case(3 Jim))

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Correlation parameter behaviour depends on a way how particles

are grouped in subgroups !

Intermediate Result

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STAR Particle Identification (NIM A499, 2003, 659-678)

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STAR Particle Identification (Yuri Fisyak)

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Run 4, AuAu 200 GeV, ~14M (ID)

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Run 4, AuAu 200 GeV, ~14M (no e+/e-)

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Run 4, AuAu 200 GeV, ~14M (no e+/e-)

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Run 4, AuAu 200 GeV, ~14M (no e+/e-)

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Run 4, AuAu 200 GeV, ~14M

nHitDedxMin = 15

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Run 4, AuAu 200 GeV, ~14M

nHitDedxMin = 10

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Run 4, AuAu 200 GeV, ~14M

nHitDedxMin = 5

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• Run 4 AuAu 200 GeV data analysis shows that correlation parameter behaviour versus centrality depends on a way how particles are grouped in the subgroups

• Particle identification and related to that number of dedx hits used in PID, nHitDedxMin = 15, which assumes better quality of the tracks creates such a correlation parameter dependences on a centrality that the signal is not unique indication of the CP violation

• We are continuing analysis to check different ideas

Summary