Hot Quarks 2004, Taos Ski Valley, New Mexico
Di-Hadron Correlations at High pt
Kirill Filimonov
Lawrence Berkeley National Laboratory
-Di-hadron correlations in pp,dAu,AuAu at 200 GeV -What should we expect in AuAu at 62 GeV?
Kirill Filimonov, Hot quarks 2004
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How it all started…
Reconstructing jets in Au+Au on a statistical basis:
C 2 ( ) 1 1
N trigger efficiency
d ( ) N ( , )
STAR, PRL 90:082302,2003 Au+Au @ 200 GeV/c 0-5% most central 4 < pT(trig) < 6 GeV/c 2 < pT(assoc.) < pT(trig)
STAR, PRL 90:03201,2003 Au+Au @ 130 GeV/c 0-10% most central 4 < pT(trig) < 6 GeV/c 2 < pT(assoc.) < pT(trig)
Kirill Filimonov, Hot quarks 2004
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Suppression of back-to-back jets
Peripheral Au + Au
C 2 ( Au Au ) C 2 ( p p) A * (1 2v 2 cos( 2 ))
2
• Near-side well-described • Away-side suppression in central collisions
STAR, PRL 90:082302,2003
STAR
Central Au + Au
near side
away side
Away side jets are suppressed!
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Back-to-back jet suppression is a final state effect
STAR, Phys.Rev.Lett.91:072304,2003
Back-to-back jets are strongly suppressed in central Au+Au collisions but not in d+Au collisions
Kirill Filimonov, Hot quarks 2004
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Di-hadron correlations wrt reaction plane
STAR, nucl-ex/0404007
pTtrigger=4-6 GeV/c, 2
=11.4 GeV/c = 9.2 GeV/c
AWAY
AWAY: = 9.2 GeV/c = 7.0 GeV/c
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“Suppression” of near-side from parton spectra
Pythia 6.131 pp 200 GeV pp 62 GeV IS=0,FS=0,KT=0
Yield ratio: /~0.3 @200 GeV ~0.1 @62 GeV Factor of ~3!
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KT- effect on the di-hadron distribution
Pythia 6.131 pp 200 GeV pp 62 GeV IS=0,FS=0,KT=0
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KT- effect on the di-hadron distribution
Pythia 6.131 pp 200 GeV pp 62 GeV IS=0,FS=0,KT=1
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Final State radiation effect
Pythia 6.131 pp 200 GeV pp 62 GeV IS=0,FS=1,KT=0
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Initial State radiation effect
Pythia 6.131 pp 200 GeV pp 62 GeV IS=1,FS=0,KT=0
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All effects combined
Pythia 6.131 pp 200 GeV pp 62 GeV IS=1,FS=1,KT=1
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pp-reference at 62 GeV
pt trigger>2.5 GeV/c, pt associated>1.0 GeV/c
pt trig, asso may be too low for comparison with Au+Au
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What to expect in Au-Au at 62 GeV? • Much weaker near-side correlations than for Au-Au at 200 GeV • “Similar” strength of away-side correlations in peripheral collisions at both energies • Away-side peak should still be suppressed in central Au-Au collisions at 62 GeV • Measurements are much more statistics hungry… but you’ll see it very soon ;-)
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