Changes between Version 7 and Version 8 of Korea2017-07-ATLAS-EXOT-2016-32


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Timestamp:
Aug 16, 2017, 2:12:57 PM (8 years ago)
Author:
Chalons
Comment:

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  • Korea2017-07-ATLAS-EXOT-2016-32

    v7 v8  
    88== 1. Analysis summary ==
    99
    10 monophoton
     10Search for physics beyond the Standard Model in events containing an energetic photon and large missing transverse momentum. Exclusion limits are also placed in models where dark-matter candidates are pair-produced. Models investigated are simplified DM models, an EFT and a high mass scalar resonance.
    1111
    1212== 2. Analysis global information ==
    … …  
    2525=== 3.1 Trigger selection ===
    2626
    27 PS: This part cannot usually be described by the fast-simulation of detector.
     27The events for the analysis were recorded using a trigger requiring at least one photon candidate above a ET_gamma threshold of 140 GeV to pass "loose" identification requirements. For events in the signal regions defined below, the efficiency of the trigger is more than 98.5%. Events are removed if they contain a bad-quality photon or jet. Events in the signal regions (SRs) are required to have the leading photon satisfying the criteria defined
     28in Section 4 and having ET_gamma > 150 GeV.
    2829
    2930=== 3.2 Object definition ===
     31* Photons: The photon identification is based on the profile of the energy deposits in the first and second layers of the electromagnetic calorimeter. Candidate photons are required tohave ET_gamma >10GeV,to satisfy the "loose" identification criteria and to be within |η| < 2.37. Photons used in the event must satisfy additionally the "tight" selection criteria, have |η| < 1.37 or 1.52 < |η| < 2.37. They must be isolated by requiring the energy in the calorimeter
     32in a cone of size  Delta R = sqrt((Delta η)^2 + (Delta Phi)^2) = 0.4 around the cluster barycentre, excluding the energy associated with the photon cluster, to be less than 2.45 GeV + 0.022 x ET_gamma.
    3033
    31 Explained here how the objects are defined.
     34* Electrons: They must fulfil the "medium" identification requirement. Electrons are required to have pT > 7 GeV and |η| < 2.47.
    3235
     36* Muons: Muon candidates must pass the "medium" identification requirement. Muons are required to have pT > 6 GeV and |η| < 2.7.   
     37
     38* Taus: The tau leptons decaying to hadrons and tau neutrinos are considered as jets.
     39
     40* Jets: Jets are reconstructed with the anti-kt algorithm with a radius parameter R = 0.4. Candidate jets are required to have pT > 20 GeV. Jets used in the event selection are required to have pT > 30 GeV and |η| < 4.5.
     41
     42* Overlap removal: If any selected electron shares its ID track with a selected muon, the electron is removed and the muon is kept, in order to remove electron candidates originating from muon bremsstrahlung followed by photon conversion. If an electron lies a distance  Delta R < 0.2 of a candidate jet, the jet is removed from the event, while if an electron lies a distance 0.2 <  Delta R < 0.4 of a jet, the electron is removed. Muons lying a distance  Delta R < 0.4 with respect to the remaining candidate jets are removed, except if the number of tracks with pT > 0.5 GeV associated with the jet is less than three. In the latter case, the muon is kept and the jet is discarded. Finally, if a jet lies a distance  Delta R < 0.4 of a candidate photon, the jet is removed.
     43
     44* ETmiss: The missing transverse momentum vector Emiss is obtained from the negative vector sum of the momenta T of the candidate physics objects. Calorimeter energy deposits and tracks are matched with candidate high-pT objects in a specific order: electrons with pT > 7 GeV, photons with ET  > 10 GeV, muons with pT > 6 GeV and jets with pT > 20 GeV.
    3345=== 3.3 Cut-flow chart ===
    3446
    … …  
    6274
    6375== 6. Questions / issues ==
    64