Jet Studies in STAR via Di-jet Triggered (2+1) Multi-hadron Correlations Kolja Kauder for the STAR collaboration Kolja Kauder for the STAR collaboration,

Jet Studies in STAR via Di-jet Jet Studies in STAR via Di-jet Triggered (2+1) Multi-hadron Triggered (2+1) Multi-hadron

CorrelationsCorrelationsKolja Kauder for the STAR collaborationKolja Kauder for the STAR collaboration

Kolja Kauder for the STAR Kolja Kauder for the STAR collaboration, QM2009collaboration, QM2009

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Jet quenching in heavy ion collisionsJet quenching in heavy ion collisions

Statistical studies of di-jets: 2+1 Statistical studies of di-jets: 2+1 correlation techniquecorrelation technique

Analysis techniqueAnalysis techniqueJet shapes, Spectra, and Fragmentation Jet shapes, Spectra, and Fragmentation functionsfunctions

Symmetric trigger resultsSymmetric trigger resultsAsymmetric trigger resultsAsymmetric trigger results

OutlookOutlook

OutlineOutline

Jet-medium Jet-medium interactioninteraction


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3<pT,trig<4 GeV/c 1.3<pT,assoc<1.8 GeV/c

M. Horner QM ‘06

3 < pT,trig < 4 GeV/c J. Putschke QM ‘06

Double-hump Double-hump structure structure

Near-side ridgeNear-side ridge

Di-hadron (1+1) correlation analysis: Di-hadron (1+1) correlation analysis: a high-pa high-pTT trigger particle associated with trigger particle associated with lower plower pTT particles particles


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Au+Au Au+Au

centralcentral

STAR, PRL102.052302

Away side: ΔAway side: Δϕϕ-Δ-Δϕϕ correlation correlation

P. Netrakanti QM’08

Near-side: Δη-Δη correlationsNear-side: Δη-Δη correlations

3-particle 3-particle correlationscorrelations

Experimental indication of Experimental indication of conical emissionconical emission

No apparent No apparent substructuresubstructure

200 GeV3<pT

Trig<10 GeV/c 1<pT

Asso<3 GeV/c

2+1 correlation 2+1 correlation techniquetechnique


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Use ‘di-jets’ to study jet-Use ‘di-jets’ to study jet-medium effectsmedium effects

““pin” the ‘jet axis’ pin” the ‘jet axis’ selecting back-to-back selecting back-to-back triggerstriggers

study correlation w.r.t. study correlation w.r.t. this axisthis axis

Courtesy of

R .Hollis

“jet-axis”

trigger (T2)

primary

trigger (T1)

associates

associates

| Δ| Δϕ-πϕ-π| < α (=0.2)| < α (=0.2)| Δ| Δϕ-πϕ-π| < α (=0.2)| < α (=0.2)

Trigger-trigger correlationTrigger-trigger correlation

T1: 5 GeV/c < pT < 10 GeV/c

T2: 4 GeV/c < pT < pTT1

Au+Au Central (12%)

Capitalize on PRL 97 (2006) 162301

Signal constructionSignal constructionOne trigger, Au+Au Central (12%)One trigger, Au+Au Central (12%)


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Mixed-event backgroundRaw 2D signal


A1: 1.5 GeV/c <pT < 4GeV/cAu+Au Central (12%)

Background Background contributionscontributions


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Correlated Correlated BackgroundBackground

Accounting for Accounting for correlated background correlated background on T1 and T2 sideon T1 and T2 side

Correlated background Correlated background approximated by di-approximated by di-hadron correlationshadron correlations

Uncorrelated Uncorrelated BackgroundBackground

Elliptic flow termElliptic flow term

Normalization: ZYAM Normalization: ZYAM vs. Absolutevs. Absolute



A1: 1.5 GeV/c < pT < 4 GeV/c

Au+Au Central (12%)

T2A1T2A1T1A1T1A1

Symmetric TriggersSymmetric Triggers

Results: 2+1 Results: 2+1 correlationcorrelation


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Kinematic constraints:



A1: 1.5 GeV/c < pT < 4 GeV/c

d+Aud+Au√√SSNNNN=200 =200 GeVGeV

Errors are statistical Errors are statistical


Results: 2+1 Results: 2+1 correlationcorrelation


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A1: 1.5 GeV/c < pT < 4 GeV/c

Au+AuAu+Au12% 12% CentralCentral√√SSNNNN=200 =200 GeVGeV



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Associated hadron Associated hadron spectraspectra

Jet region: | Δη | < 0.5

Au+Au Au+Au 12% Central, 12% Central, √S√SNNNN=200 GeV=200 GeV

d+Au d+Au √S√SNNNN=200 GeV=200 GeV

Significantly harder than uncorrelated Significantly harder than uncorrelated backgroundbackground

No appreciable difference betweenNo appreciable difference between same side and away sidesame side and away side


|| Δϕ | < 0.5 Δϕ | < 0.5

- - - - Background- - - - Background





A1: 1.5 GeV/c < pT < 4 GeV/c


1010Symmetric TriggersSymmetric Triggers

<p<pTT> and yield> and yield

No appreciable change in <pNo appreciable change in <pTT> >

Yield modification not significant Yield modification not significant within systematic errorswithin systematic errors

No difference same <-> awayNo difference same <-> away




A1: 1.5 GeV/c < pT < 4 GeV/c


|| Δϕ | < 0.5 Δϕ | < 0.5

d+Au Au+Au T1>5,T2>4 T1>5,T2>4

d+Au Au+Au T1>5,T2>4 T1>5,T2>4


- - - - Background- - - - Background


1111Symmetric TriggersSymmetric Triggers

Fragmentation function Fragmentation function estimatesestimates

Approximate fragmentation functions via

Away/SameAway/Same

Au+Au Central Au+Au Central 12%12%

Au+Au Central Au+Au Central 12%12%

d+Aud+Aud+Aud+Au

No significant modification of fragmentation functions

STAR Preliminary

Errors are statistical



Same side: pT,T1

Away side: pT,T2

Asymmetric TriggersAsymmetric Triggers

2+1 correlation2+1 correlation


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Au+AuAu+AuHT-triggeredHT-triggered√√SSNNNN=200 GeV=200 GeV

STAR Preliminary

STAR Preliminary STAR Preliminary



T1: 8 GeV < ET < 15 GeV

T2: 4 GeV/c < pT < min{pTT1,10 GeV/c}

A1: 1.5 GeV/c < pT < 10 GeV/c


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Associated hadron Associated hadron spectraspectra


T1: 8 GeV < ET < 15 GeV

T2: 4 GeV/c < pT < min{pTT1,10 GeV/c}

A1: 1.5 GeV/c < pT < 10 GeV/c

Au+AuAu+AuHT-triggeredHT-triggered√√SSNNNN=200 GeV=200 GeV

d+Au Au+Au Au+Au T1>5,T2>4 T1>5,T2>4 T1>8,T2>4

d+Au Au+Au Au+Au T1>5,T2>4 T1>5,T2>4 T1>8,T2>4





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<E> deposition for back-to-back jets

Model PredictionsModel Predictions

T. Renk

PRC78, 014903 (2008)

Charged hadron Sum-pCharged hadron Sum-pTT in correlation in correlation peaks:peaks:

Σ pΣ pTT= Σ p= Σ pT,assocT,assoc + p + pT,trigT,trigΣ pΣ pTT= Σ p= Σ pT,assocT,assoc + p + pT,trigT,trig

d + Au)= 1.64 ± 0.35 [GeV/± 0.35 [GeV/cc]]

Au + Au)= 1.50 .50 ± 0.31 [GeV/± 0.31 [GeV/cc]]

Au + Au)= 4.3 .3 ± 0.1 ± 0.1 [GeV/[GeV/cc]]

Symmetric

Asymmetric

= = Σ pΣ pTT (same)-Σ p (same)-Σ pTT (away) (away)= = Σ pΣ pTT (same)-Σ p (same)-Σ pTT (away) (away)


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SummarySummaryStudied dijet properties using 2+1 Studied dijet properties using 2+1 correlation techniquecorrelation technique

Symmetric trigger pairs:Symmetric trigger pairs:

Similar spectra for central Au+Au and Similar spectra for central Au+Au and d+Au collisionsd+Au collisions

No measurable modifications in No measurable modifications in correlations, fragmentations correlations, fragmentations functions, Σpfunctions, ΣpTT

Asymmetric trigger pairs:Asymmetric trigger pairs:

Similar peaks on same side and away Similar peaks on same side and away sideside

Softer away side spectrumSofter away side spectrum

ΣpΣpT T Estimate for energy loss Estimate for energy loss

Back-UpBack-Up


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Fragmentation Fragmentation functionfunction

Documents

Jet Studies in STAR via Di-jet Triggered (2+1) Multi-hadron Correlations Kolja Kauder for the STAR collaboration Kolja Kauder for the STAR collaboration,