Z0/?*(?l l-) jet Made in LANL

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Z0/?(?ll-)jet

Made in LANL
Dilepton Tagged JetsviaAngular Correlations

• Camelia Mironov

Paul Constantin, Gerd Kunde, Camelia
Mironov
Made in LANL (with P. Constantin G.J. Kunde)

• Signal
• Background
• Miscellaneous
• NEXT

• Introduction
• Signal
• Background
• Conclusions, applause, flowers etc.

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Azimuthal Correlations hh
hPt hadorn tagged (triggered) jet

• pp zpTassociated/pTtrigger? Fragmentation
  function
• AA distribution of particles associated with
  a trigger after medium modification
• ? have to disentangle the jet
  component from the global flow

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Azimuthal Correlations Z0/?jet
The DILEPTON is the tag
BKG B(12v2(pTasso)v2(pTtrig)cos(2??))

• ? no flow for dilepton ? flat global background
• pTjet pTZ0/? ? jet energy
  determined
• no ambiguities (p0-gt2?, ? etc) like in ?jet

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Theory ?jet
? Wang, Huang, Sarcevic PRL 77, 231 (1996) ?
Wang, Huang PRC 55, 3047 (1997)

• ? measure D(z) in pp and AA
• ?a (parton inelastic scattering mean free path)
• ? dEa/dx (parton energy loss)

? Arleo et al (hep-ph/0410088),
Arleo(hep-ph/0601075) ?-p0 and ?-? correlations
? medium modified fragmentation functions
Energy loss models (GLV, BDMS etc) connect
partonic energy loss to fundamental properties of
the medium gluon density, system size etc
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PYTHIA Signal at LHC 5.5TeV
PYTHIA v6.326
Mass_? gt12GeV (default) ? lt3.0
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PYTHIA Signal at LHC 5.5TeV
NUMBERS
Luminosity 0.5 (mbs)-1 Run time 106 (s) (2
weeks)
Z(pTgt50 GeV/c) 790
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Cross-check for the PYTHIA number
Campbell and Maltoni cross sections at NLO
MCFM (http//mcfm.fnal.gov)
BRLumirunTimeA2 720 Z0 with pTgt50GeV/c
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PYTHIA Z0 Signal
?F vs pTdilepton
zpThadron/pTdilepton
z vs pTdilepton
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Background
Heavy quarks and their semi-leptonic decay
channels
BR(B --gt lxy) 10.2
BR(D --gt lxy) 6.7
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Signal Background Theory
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Understanding background theory
CERN yellow report on heavy flavor production
hep-ph/0311048
NLO (HVQMNR) (Mangano, Nason, Ridolfi
hep-th/xxxxx) PYTHIA total
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My MNR ?F(ccbar) Distribution
ccbar independent trend in ?F with increasing
the momentum
pT(ccbar)gt20GeV/c
Pt(ccbar)gt150GeV/c
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My MNR ?F(bbbar) Distribution
bbbar change in ?F when increasing the momentum
cut
pT(bbbar)gt20GeV/c
pT(bbbar)gt150GeV/c
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Reduce Background
understand background first!!
? comon sense DCA cut on displaced lepton track
Profile histogram (valuemean, barsrms)
3ltpleptonlt5 GeV/c 5ltpleptonlt7 GeV/c 7ltpleptonlt10
GeV/c 10ltpleptonlt13 GeV/c
Dca(mm)
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Reduce background DCA
? If we assume a dca resolution in srf20µm and
sz50µm
Statistical error bars

• can identify (reject) 80 of the heavy
  background
• pT dependent trend?

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Before the end

• Use a weakly interacting probe (Z0/?(ll-)jet)
  to tackle the properties of a strong interacting
  medium
• ? weak is good (this
  time)
• Advantages over traditional h-h, ?-h analyses
  no flow, no high pT limit etc.
• Smallish rates
• ? you cant have
  everything (rates, high pT reach and purity) in
  life
• La vita seems to be bella nevertheless

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• The End

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Z0/? - jet
Initial state radiation S(pT_incomingPartons)!0
? pTjet !pTdilepton
pT lt100 lt200 lt300 lt400 lt500
() 0.00216774 4.23512e-05 2.35157e-06 3.25855e-07 5.0463e-08

• Final state radiation
• It will broden the jet
• distribution