ZZ 3e X and H 2 m 1e X Updates

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ZZ ? 3e X and H ? 2 m 1e X Updates

• Azeddine Kasmi
• Bob Kehoe
• Thanks to
• Julia, David, Daniel, Pavel, Hong

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OUTLINE

• Motivations
• Summary of previous
• Unfound electron in ZZ ? 3e sample
• Yields and kinematics for H ? 2m1e analysis
• Conclusions and Future Plans

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Motivations

• Similar to H ? 3e (a la Julia)
• Diboson decays (H ? ZZ()) have good sensitivity
  over a wide mass range.
• Four lepton ID costly in costly in efficiency in
  H ? 3l
• For the unfound electron.
• Want to use Trk/egamma
• but also try cluster-based (forward region)
• ZZ ? 3e X ( will be also extended to ZZ ? 2m1e
  )
• BG for high mass Higgs.
• Higher cross section than the Higgs, hence will
  be seen first
• Critical SM test case for 3lX selection

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Signal and Background after Pt cuts
ETmiss Isolation
ZZ ? 3e X Analysis
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Signal and Background after Pt cut and ETmiss
Isolation does not exist on Staco
H ? 2m1e X Analysis
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Use Z mass as a cut
e2
Z

• Find which combination of 2 electrons makes a Z
  for both samples ZZ and Zbb.
• Define a variable MZ_Best.
• Check the two combination M13 and M23
• The closest of them to the MZPDG is the
  MZ_Best.
• This Z_Best will be used to distinguish between
  ZZ and Zbb.
• besides the cuts mentioned above, we add
• MzPDG MZBest lt 10 GeV
• Sig_effi 40 BG_rejec 98
• SB 115
• Try to find the 4th candidate electron to use it
  to find the second Z peak

e4

e3
e1
e1
Z
Z
e2
b
b
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The 4th Electron might be seen as a jet
In the event of 3 Medium electrons are
reconstructed With Pt gt 10 GeV
Remove jets within dR lt 0.2 From any Medium
electron
ZZ sample
Does the jet candidate match The unfound
electron
Jet Candidate
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DR between Medium 3 electrons and jets in ZZ
sample
Most jets are electrons
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Jets vs Jet candidates in ZZ
Jets
Jet Candidates
Most events have at least 1 jet not matching a
medium electron
Looks like a Pt distribution of an electron from
Z
Higher number of jets per events is due to the
electrons seen as jets
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DR between 1medium electron and jets in the Higgs
sample.Jets and Jets candidates
jets
Jet candidate
Most events have at least 1 jet not matching a
medium electron
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Jets and Jet candidate in Zbb sample
Jets in Zbb sample
Jet candidate in Zbb sample
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dR between a jet candidate and the unfound truth
electron in ZZ
Most of jet candidate Match the unfound electron
There are 582 matches In dR lt 0.2

• e 582/653
• 89

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dR between a jet candidate and the unfound truth
electron in HiggsPt of the unfound truth
electronPt of the jet candidate which falls
within dR lt 0.2 from the unfound truth electron
Higgs

• 633/663
• 95

Similar shapes
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The Pt of unfound Electron(Left) in the jet
candidate(Middle) in the truth electron that do
not match the 3 medium
electron(Wright) its eta distribution
ZZ sample
Wide range in eta coverage
Similar shape
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Jet candidate Pt resolution in EMbarrel, EndCap
and FCAL
ZZ
?
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Summary table
close
The Track was also given a try but did not meet
the expectation. Need to understand !
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Pt Resolution in too case(left) Pt of the
unfound truth electron lt 20 GeV(right) Pt of the
unfound truth electron gt 20 GeV
Higgs
May use a Pt cut ( 20 GeV) on the jet candidate
to improve the resolution
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In case the jet candidate is within dR lt 0.2 from
the unfound truth electronif Z_Best is 13 so
Z_second 2first leading jet candidate if
Z_Best is 23 so Z_second 1first leading jet
candidate
ZZ Sample
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if Z_Best is 13 so Z_second 2first leading jet
candidate if Z_Best is 23 so Z_second 1first
leading jet candidate
Zbb Sample
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Apply all cuts and take the first leading jet.
Using jet candidate can improve S/B in two ways.
(ignore 4th lepton e or fake rate for now)

• Crude particle ID cuts e for e in ZZ should be
  much higher than fake rate in Zbb
• Cant distinguish jets until the use of Athena
  analysis (i.e. AOD)
• 4th lepton provides key kinematics constraints (a
  la Ryszard and Bob)
• In ZZ 2 Z masses
• In Higgs 1Z and 1 Higgs resonance
• For the moment, use the power of the latter

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MZ_Best vs. MZ_second in ZZ and Zbb
ZZ sample
Zbb sample
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Pt cuts 10 GeV, ETmiss lt 20 GeV, Isolation
etcone30/et ( lt 0.2 ) ) and MZ_Best within 15
GeV from the mean ( interval 70-100 GeV)
(MZ_second peak ( interval 80-120 GeV)
In ZZ sample 268 events out of 653 (653 medium
electron Pt gt 10 GeV) Efficiency 268/653 41
In Zbb sample No events passed
S/sqrt(SB) 268/sqrt(268) 16.37 If I say that
there was one event of Zbb x scaling factor
(188) s/sqrt(SB) 12 Does this make any sense ?
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Higgs mass with 2 reconstructed muons,
reconstructed Medium electron and the jet
candidate which falls within dR lt0.2 from the
unfound truth electron
MH 130 GeV Here it is shifted by 6 GeV
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Future Plans

• Need to do analysis on AODs to determine the jet
  candidate ID cuts
• Try the Track and egamma.
• Optimization of kinematic selections
• Use a Muon algorithm which provide isolation
• Try the ZZ analysis for 1 fb-1

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ETmiss in Signal and Background
Back up
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MZ_Best vs. MZ_second in ttbar and WZ
Back UP
ttbar
WZ