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Study of Top Quark Properties and New Physics Effects in LHC Data Analysis

This thesis project involves the investigation of top quark properties and potential effects of new physics in high-energy particle collisions at the Large Hadron Collider (LHC). It includes a comprehensive study of top quark production, decay modes, and branching ratios, utilizing data analysis techniques to reconstruct top quark events in different channels. The work also focuses on the evaluation of trigger efficiency, event reconstruction, and signal-background separation, aiming to provide insights into the Standard Model and potential resonances in the top quark sector.

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Study of Top Quark Properties and New Physics Effects in LHC Data Analysis

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  1. My Thesis Project Study of the Top Quark Properties and Effect of New Physics Thesis Preparation LTPPM : January 2009 .... • Stage LPC 2009 : 2 months (LIA & ILCP) • Stage LPC 2010 : 4 months (LIA & ILCP) • Stage CERN : ....2 months

  2. + (90%) (10%) The Quark Top at LHC Production of tops pairs SM: Decay Full hadronic Channel semi-leptonic Channel di-leptonic Channel Branching Ratio

  3. Stage LPC:22 Mai-5 Aout 2009 • Familiarization with the ATLAS software environment : Athena, ROOT. • beginning of an analysis: - ttbar full hadronic channel (tt → Wb Wb → qqb qqb) - production of events • reconstruction of events with 0b-tag: study of jets combinations methods : Meth1:  select the two W light jets :   Min χ2 = Σ (Mjj-Mw) 2 / б2    to associate the to good top : choice Mt1-Mt2 minimum      Meth2: Meth1 + remove all jets combinations with Pb <Pj1 <PJ2 in CMtopResults: choosing the right combination for W1 and W2 = 27%                   Choosing the right combination for t1 and t2 = 41%

  4. …..2010work Study of the ttbar events in the Semi-leptonic Channel ttbarResonances Search • Study of the electron and muon trigger efficiency with simulation (10 TeV) • Resuming the analysis "10TeV" for the study at 7 TeV (simulation data)GOALS: • Learning a complete analysis • Production of signal & BGs • Selection and reconstruction •  report

  5. Study of the trigger Efficiency Avalables Simulations • SM, Z '(500,700,1000,2000,2500,3000 GeV) MC => No trigger Information.   =>Assumptions: All SM events with 1 lepton pT> 20GeV must pass the  lepton trigger: (EF_e15_medium (e); EF_m15 (μ)) • New MC with SM Trigger Info => plots for trigger selected eventswith cutlepton Pt> 20GeV (μ)EF_m15 + cut pT>20 GeV (e)EF_e15_medium + cut pT>20 GeV

  6. Reconstruction of Events : tt→ Wb Wb → blטbjj(2b-tag) • Tops Reconstruction T_had-> 3jet W_had = two light jets the closest in ΔR top_had = W_had and b-jet closest ΔR T_lept: W_lept = lepton + MET + pz constraint on MW_PDG Top_lept = W_lept+ bjet • Reconstruction improved for energetic tops (T_hadwith less than 3jet)               (M_jet_Max = the highest mass of the jet in the evt) •  if M_jet_Max <65 GeV T_had-> 3jetsstandard reconstruction • if 65 <M_jet_Max<130 GeV T_had-> 2jetsT_had isthe jet_max & jet the closest in ΔR • if M_jet_Max > 130 GeV T_had-> 1jetT_had is the jet with the highest mass

  7. SIGNAL Z’reconstructed Reconstruction Of Events : tt→ Wb Wb → blטbjj ttbar mass reconstructed from different samples of BGs.

  8. Stage CERN: Octobre…2010 study of Uniformity in Φ Of theTilecal QualificationWork

  9. Stage CERN: Octobre…2010 • First study of uniformity from an available Ntuple (isolated tracks)   (in progress)- Selection of isolated tracks (ΔR = 0.4)- Determination of the entry point of the track in the module- Calorimetric energy deposited (ΔR = 0.1 around the track direction)- Distribution of the energy deposited in function of Tile Module N°.

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