= The first !MadAnalysis 5 workshop on LHC recasting @ Korea =
= Analysis 8: ATL-PHYS-PROC-2O16-117 =

||= Students =|| ||  || || || || ||
||= Supervisor(s) =|| Eric Conte || Benjamin Fuks || || || || ||


== 1. Analysis summary ==

A measurement of the tt¯Z and tt¯W production cross sections in final states with:
*   two same-charge muons: one muon coming from Z/W and one from the top decay.
*   or three leptons (electrons or muons),
*   or four leptons (electrons or muons): only ttZ case where Z and the 2 top quarks are decaying leptonically.
The analysis uses a data sample of proton-proton collisions at s√=13 TeV recorded with the ATLAS detector at the Large Hadron Collider in 2015, corresponding to a total integrated luminosity of 3.2 fb−1. The inclusive cross sections are extracted using likelihood fits to signal and control regions, resulting in σtt¯Z=0.9±0.3 pb and σtt¯W=1.5±0.8 pb, in agreement with the Standard Model predictions.

== 2. Analysis global information ==

*  ATLAS contact person: nobody
*  Center of mass energy: 13 TeV
*  Integrated luminosity: 3.2 fb−1
*  Link to arXiv: https://arxiv.org/abs/1609.01599
*  Link to the collaboration page: https://atlas.web.cern.ch/Atlas/GROUPS/PHYSICS/PAPERS/TOPQ-2015-22/
*  Link to CDS: https://cds.cern.ch/record/2211022?ln=fr
*  Link to Inspire: http://inspirehep.net/record/1485353
*  Link to Rivet analyses: https://atlas.web.cern.ch/Atlas/GROUPS/PHYSICS/PUBNOTES/ATL-PHYS-PUB-2016-005/

== 3. Selection description ==

=== 3.1 Trigger selection ===

Only events using single-electron OR single-muon triggers are accepted:
- single-electron: one electron with pT > 24 GeV
- single-muon: one muon with pT > 20 GeV

PS: This part cannot usually be described by the fast-simulation of detector.

=== 3.2 Object definition ===

*   electron: 
      * pT > 7 GeV,
      * |eta|<2.47. Are excluded electrons in the end-cap, i.e. 1.37 < |eta| < 1.52.
      * 'medium' likelihood identification.
      * transverse impact parameter: |d0|/err(d0) < 5.
      * longitudinal impact parameter: |z_0 x sin\theta | < 0.5 mm
      * isolation criterion: 
         * sum PT of tracks in a cone around the electron (the electron track is subtracted) of size = min(10 GeV/PT,0.2) < 6% electron PT.
         * sum ET of clusters in a cone around the electron (the electron cluster is subtracted) of size DR=0.2 < 6% electron PT. 
       
 
*   muon: 
      * pT > 7 GeV
      * |eta|<2.4
      * 'medium' identification.
      * transverse impact parameter: |d0|/err(d0) < 3.
      * longitudinal impact parameter: |z_0 x sin\theta | < 0.5 mm
      * isolation criterion: sum PT of tracks in a cone around the muon (the muon track is subtracted) of size = min(10 GeV/PT,0.3) < 6% muon PT. 
 
*   jet:
      * clustering: anti-kT with =0.4
      * pT > 25 GeV
      * |eta|<2.5
      * Pile-up rejection: jets with pT < 60 GeV and |η| < 2.4 are required to satisfy pile-up rejection criteria (JVT)

*   b-jet: MV2c20 algorithm. In simulation, the tagging algorithm gives a rejection factor of about 130 against light-quark and gluon jets, and about 4.5 against jets containing charm quarks.
    
*   preventing double-counting:
      * the closest jet within DR=0.2 cone of an electron is removed.
      * if, after the previous selection cut, the nearest jet of an electron is in DR=0.4 cone, then the electron is removed.
      * muons in a DR=0.4 cone around a given jet are removed. BUT if the jet has fewer than three associated tracks, the muon is kept.


=== 3.3 Cut-flow chart ===

=== 3.4 Definition of exotic observables ===

Like SUSY transverse observable. Notice that classical MT2 & MT2W are encoded within the !MadAnalysis framework.

== 3. Detector simulation ==

Can we use the last release of the Delphes package with the CMS/ATLAS MA5tune-card? or do need to improve the simulation? 

== 4. Validation material ==

=== 4.1 Monte-Carlo samples ===

*   LO/NLO?
*   Model used:
*   MC generator program (name + version):
*   Shower program (name + version):
*   Tune of Pythia:
*   PDF set:
*   ME/PS merging????

=== 4.2 Reference plots / cut-flows ===

*   List of validation material

== 4. Validation results ==

== 5. Reinterpretation (optional) ==

== 6. Questions / issues ==