ATLAS???????Fake Lepton???? Higgs

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ATLAS???????Fake Lepton????HiggsSUSY????????????
?

• ????????????
• ????????????
• (ICEPP and KEK)

2
Motivation

• SUSY??1 leptonjets???channel????????LHC ?
• ?QCD multi-jet event?????????????(µb)?
• jet?lepton?missID??????background????????
• ??????
• Higgs????VBF H?tt???channel????
• ???????QCD multi-jet?t?lepton?missID??????
• background??????????????
• ????background????????

3
Contents

• Fake Lepton???
• Fake Lepton??????
• Lepton?Efficiency???
• Background???

Full Simulation
Fast Simulation
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Fake Lepton ???
Electron
p?p0???? ????p??????E/p1
????pair production ???electron?soft
e-
p


?
?
p0
?
e
heavy flavor ? semi-leptonic decay
HCAL
EM
TRT
HCAL
EM
TRT
ATLAS EMCAL?segmentation??? ???????????
soft?hadronjet
Muon
B?D
Pion decay in flight P???????
Pion punch-through HCAL?minimum ionization
?

µ

p
p
l
???jet??? fake lepton?????
?
HCAL
EM
TRT
HCAL
EM
TRT
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Fake lepton??

• B?Dµ? ??

EMCAL
HCAL
Muon System
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Efficiency and Rejection

• Fake rate 1/Rejection Factor
• miss ID lepton/reconstructed Jets
• Fake rate?reconstructed jets????missID???lepton???
  ????
• ????????Reconstructed jet???light flavor???heavy
  flavor??
• ??miss ID lepton??????????
• light flavor punch-through??
• heavy flavor ( b?c ) semi-leptonic
  decay??
• ??????2????????????fake rate??????

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Fake rate
Heavy flavor
Light flavor
fake rate
fake rate
muon electron
muon electron
Pt(GeV)
Pt(GeV)
fake rate 10-3 10-4 Jet?lepton?Pt??????????fake
rate???????????? Muon????????????????? Heavy
flavor??????fake rate?????
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Efficiency vs Fake rate (Electron)
Isolation5GeV ??
e-
fake rate
? 2GeV ? 10GeV ? 5GeV ? 20GeV
?R0.45 Etlt5GeV
electron cluster??????R0.45 ??Et deposit?5GeV??

• Electron?isolation???
• 2,5,10,20GeV??????
• plot?
• isolation????????
• efficiency?????????
• ?fake rate???????
• isolation?????????
• efficiency???????
• 510GeV????isolation cut

efficiency
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Efficiency vs Fake rate (Muon)

• Muon?isolation???
• 5,10,20,30GeV??????
• plot?
• ?????????????
• 1020GeV????isolation
• ?????????

fake rate
? 5GeV ? 20GeV ? 10GeV ? 30GeV
efficiency
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Fake rate ???
10-4
Pt(GeV) jet?e jet?µ bjet?e bjet?µ bjet?t
15-35 6.70.8 2.30.5 197.7 03.2 259.0
35-50 6.01.3 0.60.4 107.2 05.1 107.2
50-80 3.81.0 2.20.7 3.70.4 7.55.2 3.73.7
80-130 3.81.0 0.30.3 04.2 04.2 04.2
130-200 3.41.0 0.60.4 05.2 5.25.2 05.2
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Determination of fake rate by Experiment

• Nreco leptons eNL rj(e)NJ rb(e)NB
• fake rate (rj(e)NJ rb(e)NB) / Nreco leptons
• rj(e) fake rate by light flavor jets
• rb(e) fake rate by heavy flavor jets
• ???process??fake rate????????????
• N???????????
• r?MC???????
• Drell-Yan, top, SUSY(SU3) sample ????????????????
• ?????

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DY, top and SUSY sample
Expected range for the 5GeV isolation condition
rj 4x10-4 rB 5x10-4 assumed
20GeV
10GeV
5GeV
isolation Etlt 2GeV

• DY?top??????fake rate????????_at_isolation 5GeV
• DY?????control?????efficiency, fake rate???????
• ????????SUSY?efficiency, fake rate????????????????
  ??????

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Background ???

• Full Simulation????Fake rate? 10-310-4???????
• ????
• Fast Simulation??????QCD multi-jets? fake
  lepton???????Background??????

QCD multi-jet event
SUSY 1lepton mode? Background???
l
missID lepton
soft?jet
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SUSY QCD multi-jets

• QCD multi-jets
• s190nb(4jet??,ptgt50GeV)
• L10fb-1
• Background?QCD multi-jet?
• ?????Fake rate?lepton?
• ????????
• low Meff??(1TeV)?
• background????????
• ????????
• (MeffmissEtSpt)

signal background
events/400GeV
m( ),m( )1TeV
Meff(GeV)
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VBF H?tt ?h?l??
mH120GeV
events/5GeV
signal BG average
QCD multi-jet?miss ID bbjj?ltaujj jjjj?
ltaujj ?background????
Mtt(GeV)
L30fb-1??Mtt distribution ?????????background???
???? 110135GeV? signal12 events
background6events Background??????????
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Summary

• Fake Rate?10-310-4?????????
• Electron?isolation???510GeV???????Muon?????1020G
  eV??????????????????????????
• ??????Fake Rate?????Muon, Electron?Fake?SUSY
  1lepton mode????background??????????????
• ????VBF process??Fake lepton????background????????
  ?????????????????Lepton ID??????????

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Lepton ID
electron
TRT hit
?R0.45 Etlt5GeV

tracker
e-
HCAL
EM
Inner
Ptgt15GeV,?lt2.5
0.7ltE/plt1.4
Electron?EMCAL????????????????????deposit???
muon
?R0.45 Etlt10GeV

tracker
µ-
HCAL
EM
Inner
Ptgt15GeV,?lt2.5
Muon?minimum ionization???????Muon Chamber ?hit???
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Efficiency vs Fake rate
electoron
muon
15-35GeV 80-130GeV 35-50GeV
130-200GeV 50-80GeV
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Atlas detector

• Inner
• Si strip,pixel , TRT ,solenoid
• s(pt)/pt0.4pt
• EMCAL
• LAr, Accordion
• s(E)/E10/vE200MeV/E0.7
• HCAL
• LAr, Tile
• Muon detector
• Troidal magnet
• s(pt)2.5_at_100GeV

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VBF H?tt ?h?l??
mH120GeV
events/5GeV
signal background bg average
QCD multi-jet bbjj?ltaujj jjjj?
ltaujj ?background????
Mtt(GeV)
30fb-1??Mtt distribution 110135GeV?estimated
cross section signal0.4fb
background0.2fb Ba
ckground??????????