Meetings (weekly)

*Thursday, 7:00 am (CA) / 10:00 am (FL) / 4:00 pm (CERN)

Meetings are held in Philip's Zoom room

Indico agenda

Presentations

People

Claudio Campagnari (UCSB)
Philip Chang (UF)
Keegan Downham (UCSB)
Matthew Dittrich (UF)

Data and MC Samples

A google spreadsheet containing the list of short names for all samples used in the analysis can be found here

The full list of samples (will full sample names) can be found here.

Skimming

There will be 2 sets of skims for 2016-2018 data/MC: an inclusive 4-lepton skim and a 3-lepton skim. For a first skim, the selected leptons will satisfy the following criteria

• Muons
  • looseId = 1
  • |η| < 2.4
  • p_T > 10 GeV
  • pfIsoId >= 1
• Electrons
  • mvaFall17V2noIso_WPL = 1
  • |η| < 2.5
  • p_T > 10 GeV
  • pfRelIso03_all < 0.4

Skims for signal and background MC can be found in Keegan's ceph area on UAF: /ceph/cms/store/user/kdownham/skimOutput/WWZ_4L/

A new set of skims, made for the purposes of testing the new lepton ID (see pre-selection for details), has been made. This is an inclusive 4-lepton selection that requires

• Muons
  • miniPFRelIso_all < 0.4
  • mediumId = true
  • |η| < 2.4
  • p_T > 10 GeV
• Electrons
  • miniPFRelIso_all < 0.4
  • |η| < 2.5
  • p_T > 10 GeV

Skims for testing the new lepton ID can be found in Keegan's ceph area on UAF: /ceph/cms/store/user/kdownham/skimOutput/WWZ_newLepID/

Most recent version

The most up-to-date version of the skims is an inclusive 3-lepton skim that is used for both the 3-lepton+tau and 4-lepton analyses. It can be found in Keegan's storage area on ceph in the following directory:

/ceph/cms/store/user/kdownham/skimOutput/3LepTau_4Lep/

This set of skims is compatible with the new lepton ID (TOP-UL MVA ID) and utilizes the following selection criteria for leptons:

• 3 or more leptons (electrons or muons) satisfying

Pre-Selection (Old Lepton ID)

This analysis targets the 4-lepton final state. The pre-selection criteria is as follows:

• Preselection: exactly 4 leptons satisfying the Common veto ID (see section "Skimming" for the definition)
• Lepton IDs: Leptons are categorized as a Z-candidate or a W-candidate. The criteria for electron and muon IDs for W and Z candidates are
  • Electrons
    • Z candidate (ZID)
      • ID: MVA POG Loose NoIso
      • |IP_3D/σ_IP3D| < 4
      • I_{rel,R=0.3,EA,Lep} < 0.2 (Not used)
    • W candidate (WID)
      • ID: MVA 90% Iso
      • |IP_3D/σ_IP3D| < 4
      • I_{rel,R=0.3,EA,Lep} < 0.2 (Not used)
  • Muons
    • Z candidate (ZID)
      • ID: Medium
      • |IP_3D/σ_IP3D| < 4
      • I_{rel,R=0.4,Δβ} < 0.25
    • W candidate (WID)
      • ID: Medium
      • |IP_3D/σ_IP3D| < 4
      • I_{rel,R=0.4,Δβ} < 0.15
• Z Candidate Selection: The pair of leptons passing the ZID requirement with same flavor, opposite charge, that have an invariant mass closest to the Z boson mass. Both leptons are also subject to the following p_T and m_ll requirements:
  • leading Z candidate lepton: p_T > 25 GeV
  • subleading Z candidate lepton: p_T > 15 GeV
  • |m_ll - m_Z| < 10 GeV
• W Candidate Selection: The remaining two leptons (the non-Z candidates) passing the WID requirements are then chosen as the W lepton candidates. We require the W lepton candidates to have opposite charge. Both leptons are subject to the following p_T requirements:
  • leading W candidate lepton: p_T > 25 GeV
  • subleading W candidate lepton: p_T > 15 GeV
• QCD low mass resonance veto: Any opposite charge pair of leptons must have an invariant mass > 12 GeV
• b-tagged jet veto: selected events must have no b-tagged jets

Pre-Selection (New Lepton ID)

This analysis targets the 4-lepton final state. The selection for leptons is as follows:

• Preselection: exactly 4 leptons satisfying the following criteria
  • Muons:
    • p_T > 10 GeV
    • |η| < 2.4
    • |d_xy| < 0.05 cm
    • |d_z| < 0.1 cm
    • |IP_3D/σ_IP3D| < = 8
    • miniPFRelIso_all < 0.4
    • mediumId = true
    • MVA score > 0.64
  • Electrons:
    • p_T > 10 GeV
    • |η| < 2.5
    • |d_xy| < 0.05 cm
    • |d_z| < 0.1 cm
    • |IP_3D/σ_IP3D| < = 8
    • miniPFRelIso_all < 0.4
    • lostHits < = 1
    • convVeto = true
    • tightCharge = 2
    • MVA score > 0.81
• Lepton p_T : We require the leading (subleading) lepton in the event to have p_T > 25 (15) GeV . The third and fourth leptons in the event are both required to have p_T > 10 GeV .
• Z Candidate Selection: The pair of leptons passing the above Preselection requirement with same flavor, opposite charge, that have an invariant mass closest to the Z boson mass. Both leptons are also subject to the following requirements:
  • |m_ll - m_Z| < 10 GeV
  • both leptons: |IP_3D/σ_IP3D| < 4
  • for electrons: relIso03_all < 0.2
• W Candidate Selection: The remaining two leptons (the non-Z candidates) passing the above Preselection requirements are then chosen as the W lepton candidates. We require the W lepton candidates to have opposite charge. Both leptons are subject to the following additional requirements:
  • both leptons: |IP_3D/σ_IP3D| < 4
  • for electrons: relIso03_all < 0.2
• QCD low mass resonance veto: Any opposite charge pair of leptons must have an invariant mass > 12 GeV
• b-tagged jet veto: selected events must have no b-tagged jets
  • b-tagged jets: jets passing loose WP of btagDeepB algorithm

Event Categorization

Events passing the pre-selection are categorized according to the flavors of the W candidate leptons. Two categories are defined: the opposite flavor category (eμ) and the same flavor category (ee/μμ). Below is a brief description of the dominant backgrounds in each category and the selections made to address said backgrounds:

• eμ: The main backgrounds in this category are ZZ--> ττ --> eμ (for m_ll,Wcands < 100 GeV ) and ttZ (for m_ll,Wcands > 100 GeV ). The ZZ background is reduced heavily by cutting on the m_T2 variable, while the ttZ background is largely unaffected by cutting on m_T2 due to the similar kinematics as the signal. Because of this, events with m_ll,Wcands < 100 GeV are required to have m_T2 > 25 GeV , while events with m_ll,Wcands > 100 GeV are not subject to any cut on m_T2.
• ee/μμ: The main background in this category is ZZ--> 4l. No additional selection is applied to this category prior to binning (see sec. "Binning").

Signal Regions

Events in the eμ (ee/μμ) category are further separated into four (three) signal regions (SRs) based on m_ll,Wcands (p_T,miss, p_T,4l). The signal regions for both categories are given below:

• ee/μμ:
  • Bin A: p_T,miss > 120 GeV
  • Bin B: 70 GeV < p_T,miss < 120 GeV , 40 GeV < p_T,4l < 70 GeV
  • Bin C: 70 GeV < p_T,miss < 120 GeV , 70 GeV < p_T,4l
• eμ:
  • Bin 1: 0 GeV < m_ll,Wcands < 40 GeV
  • Bin 2: 40 GeV < m_ll,Wcands < 60 GeV
  • Bin 3: 60 GeV < m_ll,Wcands < 100 GeV
  • Bin 4: 100 GeV < m_ll,Wcands

Preliminary (Baseline) Results

Cut Based Analysis (4-lepton channel)

All plots for the baseline selection are stored here on Keegan's public UAF area

The vvvtrees used to get these numbers are in the following area of Keegan's UAF directory:

/ceph/cms/store/user/kdownham/VVVAnalysis/070623_masterSync/

The baseline yields in the 4-lepton signal regions are as follows:

Combined Significance: using signal+background MC in the 4-lepton SRs, we obtain a combined significance of 4.46σ (via Higgs Combine Tool)

BDT Analysis

BDT Training Information:

To provide better rejection against the major backgrounds (ZZ and ttZ), a total of 4 different BDTs are trained (2 per signal process, and 2 per channel). Enumerating this, we have:

• WWZ vs Backgrounds (ZZ,ttZ) in the opposite-flavor channel
• ZH vs Backgrounds (ZZ,ttZ) in the opposite-flavor channel
• WWZ vs Backgrounds (ZZ,ttZ) in the same-flavor channel
• ZH vs Backgrounds (ZZ,ttZ) in the same-flavor channel

For the first version of the BDT (v1), the important information is listed below:

• List of input variables that were trained on is here
• xml files containing the weights for the opposite flavor and same flavor BDTs
• Plots will be shown here (WIP)

Training Region (TR) Selection

Events passed to the BDT for training and testing are subject to the so-called "training region" selection, which is a subset of the full cut-based selection. A slide showing the training region selection can be found below:

• Training region selection (v1): here (slide 3)