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Dilepton Tagged Jets via Angular Correlations. Z0/ γ *( l + l - )+jet Made in LANL. Paul Constantin, Gerd Kunde, Camelia Mironov. Made in LANL (with P. Constantin & G.J. Kunde). Camelia Mironov. S ignal B ackground M iscellaneous NEXT. Introduction Signal Background

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Z0 l l jet made in lanl

Dilepton Tagged JetsviaAngular Correlations

Z0/γ*(l+l-)+jetMade in LANL

Paul Constantin, Gerd Kunde, Camelia Mironov

Made in LANL

(with P. Constantin & G.J. Kunde)

Camelia Mironov

  • Signal

  • Background

  • Miscellaneous

  • NEXT

  • Introduction

  • Signal

  • Background

  • Conclusions, applause, flowers etc.


Azimuthal correlations h h
Azimuthal Correlations: h+h

TriggerParticle

Back side

C(ΔΦ)

Sameside

Associated

Particles

BKG = B(1+2v2(pTasso)v2(pTtrig)cos(2))

CARTOON

flow+jet

A+A

flow

jet

p+p

hPt hadorn tagged (triggered) jet

  • p+p : z=pTassociated/pTtrigger Fragmentation function:

  • A+A: distribution of particles associated with a trigger aftermedium modification

     have to disentangle the ‘jet’ component from the global ‘flow’


Azimuthal correlations z0 jet
Azimuthal Correlations: Z0/γ*+jet

The DILEPTON is the tag

BKG = B(1+2v2(pTasso)v2(pTtrig)cos(2))

no flow for dilepton flat global background

  • pTjet ~ pTZ0/γ* jet energy determined

  • no ambiguities (π0->2γ, η etc) like in γ+jet


Theory jet
Theory: γ+jet

z = pT/pjet

 Wang, Huang, Sarcevic PRL 77, 231 (1996)

 Wang, Huang PRC 55, 3047 (1997)

  •  measure D(z) in pp and AA

  • λa (parton inelastic scattering mean free path)

     dEa/dx (parton energy loss)

 Arleo et al (hep-ph/0410088), Arleo(hep-ph/0601075): γ-π0 and γ-γ 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


Pythia signal at lhc 5 5tev
PYTHIA Signal at LHC =5.5TeV

PYTHIA v6.326

Mass_γ* >12GeV (default)

|η| <3.0


Pythia signal at lhc 5 5tev1
PYTHIA Signal at LHC =5.5TeV

~NUMBERS:

Luminosity = 0.5 (mbs)-1

Run time = 106 (s) (2 weeks)

Z(pT>50 GeV/c) ~790


Cross check for the pythia number
Cross-check for the PYTHIA number …

Campbell and Maltoni: cross sections at NLO == MCFM (http://mcfm.fnal.gov)

BR*Lumi*runTime*A^2 ~720 Z0 with pT>50GeV/c


Pythia z0 signal
PYTHIA Z0 Signal

ΔΦ vs pTdilepton

z=pThadron/pTdilepton

z vs pTdilepton


Background
Background

| | | | | | | |

| | | |__| | | |__

____ | |_____

Heavy quarks and their semi-leptonic decay channels

BR(B --> lxy) ≈ 10.2%

BR(D --> lxy) ≈ 6.7%


Signal background theory
Signal & Background : Theory

Gale, Srivastava,Awes nucle-th/0212081


Understanding background theory
Understanding background: theory

CERN yellow report on heavy flavor production: hep-ph/0311048

NLO (HVQMNR) (Mangano, Nason, Ridolfi hep-th/xxxxx)

PYTHIA total


My mnr ccbar distribution
My MNR: ΔΦ(ccbar) Distribution

ccbar: independent trend in ΔΦ with increasing the momentum

pT(ccbar)>20GeV/c

Pt(ccbar)>150GeV/c


My mnr bbbar distribution
My MNR: ΔΦ(bbbar) Distribution

bbbar: change in ΔΦ when increasing the momentum cut

pT(bbbar)>20GeV/c

pT(bbbar)>150GeV/c


Reduce background
Reduce Background

plepton

pmeson

vtx

(0,0,0)

lepton = e±, μ±

meson = D±, B±

dca

…understand background first!!

 comon sense: DCA cut on displaced lepton track

Profile histogram

(value=mean, bars=rms)

3<plepton<5 GeV/c

5<plepton<7 GeV/c

7<plepton<10 GeV/c

10<plepton<13 GeV/c

Dca(mm)


Reduce background dca
Reduce background: DCA

 If we assume a dca resolution in σrφ~20μm and σz~50μm

Statistical error bars

  • can identify (reject) ~80% of the heavy background

  • pT dependent trend?


Before the end
Before the end …

  • Use a weakly interacting probe (Z0/γ*(l+l-)+jet) to tackle the properties of a strong interacting medium

     weak is good (this time)

  • Advantages over ‘traditional’ h-h, γ-h analyses: no flow, no high pT limit etc.

  • ‘Smallish’ rates

     you can’t have everything (rates, high pT reach and purity) in life

    La vita seems to be bella nevertheless …



Z0 jet
Z0/γ* - jet

γ*/Z0

γ*/Z0

γ*/Z0

γ*/Z0

Initial state radiation

· Σ(pT_incomingPartons)!=0 

pTjet !=pTdilepton

  • Final state radiation

  • It will broden the jet

    distribution


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