= 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 === '''Common:''' * 0. Trigger confirmation: at least one lepton (muon/electron) with PT > 25 GeV '''1. Analysis 1: SS-muons''' * 1.1. 2 muons of same charge, with PT > 25 GeV * 1.2. Events with additional leptons are vetoed * 1.3. MET > 40 GeV * 1.4. HT > 240 GeV * 1.5. At least 2 b-jets '''2. Analysis 2: trilepton analysis''' * 2.1. Exactly 3 leptons * 2.2. 2 opposite sign, same flavour leptons, and * 2.2. Leading lepton with PT > 25 GeV, the other leptons with PT > 20 GeV * 2.3. Defining 4 signal regions according the final states: * 3l-Z-1b4j * 3l-Z-2b3j * 3l-Z-2b4j * 3l-noZ-2b * 2.4. Compatibility with a Z: * [3l-Z-1b4j]+[3l-Z-2b3j]+[3l-Z-2b4j]: compatible with a Z i.e. (invM-MZ)<10 GeV * [3l-noZ-2b]: not compatible with a Z i.e. (invM-MZ)>10 GeV * 2.5. Number of light jets (no b-jet): * [3l-Z-2b3j]: #jets = 3 * [3l-Z-1b4j]+[3l-Z-3b4j]: #jets >= 4 * [3l-noZ-2b]: #jets = 2, 3 or 4 * 2.6. Number of b-jets: * [3l-Z-1b4j]: #b-jets = 1 * [3l-Z-2b3j]+[3l-Z-3b4j]+[3l-noZ-2b]: #b-jets >= 2 '''3. Analysis 3: tetralepton analysis''' * 3.1. Exactly 4 leptons * 3.2. 2 pairs of opposite sign * 3.3. At least one pair must have same flavour leptons * 3.4. We define Z1 = reconstructed Z from opposite-sign same-flavour pair the closest to the Z mass. We define Z2 = reconstructed Z from the other pair (same-flavour or not). * 3.5. Defining 4 signal regions according the final states: * 4l-DF-1b * 4l-DF-2b * 4l-SF-1b * 4l-SF-2b * 3.5. Cut on PT34 = scalar sum of the transverse momenta of the third and fourth leptons: * [4l-DF-1b]: PT34 > 35 GeV * [4l-SF-1b]: PT34 > 25 GeV * 3.6. MET: * [4l-SF-1b]: If |MZ2-MZ| > 10 GeV then imposing MET > 40 GeV else imposing MET > 80 GeV * [4l-SF-2b]: If |MZ2-MZ| < 10 GeV then imposing MET > 40 GeV * 3.7. Number of b-jets: * [4l-DF-1b]+[4l-SF-1b]: #b-jets = 1 * [4l-DF-2b]+[4l-SF-2b]: #b-jets >= 2 === 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 === * Final number of signal events after the selection in each signal region: https://atlas.web.cern.ch/Atlas/GROUPS/PHYSICS/PAPERS/TOPQ-2015-22/tabaux_06.pdf * Plots for Analysis 1: SS-muons * Plots for Analysis 2: trileptons * Plots for Analysis 3: tetraleptons * Rivet analyses == 4. Validation results == == 5. Reinterpretation (optional) == == 6. Questions / issues ==