Jet Reconstruction in d+Au Collisions at RHIC-PHENIXncgrau/physics/talks/...2009/10/17 · Jet...
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Jet Reconstruction in d+Au Collisions at RHIC-PHENIX Nathan Grau Columbia University, Nevis Laboratories for the PHENIX Collaboration
Transcript of Jet Reconstruction in d+Au Collisions at RHIC-PHENIXncgrau/physics/talks/...2009/10/17 · Jet...
Jet Reconstruction in d+AuCollisions at RHIC-PHENIX
Nathan GrauColumbia University, Nevis Laboratoriesfor the PHENIX Collaboration
10/17/2009Joint APS/JPS DNP
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Outline
Multitude of measurements with jets in d+Au Focus first on Di-jet correlations
Measuring jets in d+Au collisions withPHENIX
Di-jet Δφ correlations Future outlook
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Physics With Jets in d+Au: Cronin
Anti-shadowing of nPDF ==> multiplescattering
Multiple scattering would tend to broaden theback-to-back di-jet correlations
Important constraint on jet quenching in A+Asince any multiple scattering energy lossmodel must describe both the cold nuclearand hot nuclear matter effects.
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Physics With Jets in d+Au: Cronin No conclusive
evidence of di-jet broadeningat RHIC fromtwo-particlecorrelations
Di-jet resultsfrom STARmay indicateotherwise.Circle - π+/--h
Cross - π0-h
PHENIX PRC 73 (2006) 054903
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Jets in PHENIX Combine
DC-PC tracks with pT> 450 MeV
EMCal clusters withpT > 400 MeV
Reject electronconversions
Remove clustersassociated withtracks
Consider jets with Raw pT > 5 GeV # constituents > 2
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Anti-kT Jet Algorithm
Anti-kT recombination algorithm Collinear and infrared safe algorithm Combines nearest, hardest particles first and
works outwards from that jet Opposite approach to kT algorithm combination
makes jets essentially conical with radius R. Use FastJet package anti-kT algorithm with
R=0.3
Cacciari, Salam, and Soyez
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Anti-kT Jet Algorithm
Same event run with kT and anti-kT algorithms They find the same jets, but the shapes are different
p+p eventG. Soyez RHIC-AGS Users’ Meeting
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Jets in PHENIX
η
φ
Raw pT: 13.5 GeV3 clusters2 tracks
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Di-jets in PHENIX
η
φ
Raw pT: 7.47 GeV2 clusters2 tracks
Raw pT: 9.63 GeV2 clusters2 tracks
Δφ = 3.36 rad
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Δφ Di-jet Correlations Correlate the
highest pT jetsin the event
Define leadingjet withhighest rawreconstructedpT
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Δφ Di-jet Correlations
Back-to-back correlations
Correlate thehighest pT jetsin the event
Define leadingjet withhighest rawreconstructedpT
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Δφ Di-jet Correlations
Split jetsBack-to-back correlations
Correlate thehighest pT jetsin the event
Define leadingjet withhighest rawreconstructedpT
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Centrality Dependence
0-20% 20-40%
40-88%
Access tolength-dependence ofmultiplescattering
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Looking Forward
First measurements of fully reconstructed jets ind+Au using the PHENIX detector. Δφ correlations of di-jet signal is seen
A wealth of physics awaits Dijet broadening Data to constrain nPDFs Fragmentation photons Heavy flavor jets Correlations between forward/backward particles and mid-
rapidity jets Etc.
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Backup
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Physics With Jets in d+Au: nPDFs Jets can reach to higher x and Q2 than single particle observables? Jets possibly allow constraint of EMC region at RHIC
Constrain high-x == constrain low-x because of momentumconservation
JHEP04(2009)065
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Physics With Jets in d+Au: nPDFs Centrality-dependence == measure of impact parameter-
dependence of nPDFs. These are critical inputs not only at RHIC but at the LHC.
JHEP04(2009)065
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Higher Leading Jet pT Correlations
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Higher Leading Jet pT Correlations
