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Theses

Forward-Backward asymmetry in top pair production at the ILC

Abstract : This thesis is done in the framework of the ILC. The determination of the electroweak couplings of the top quark, is one of the tasks at the ILC. The thesis is dedicated to the measurement of the Forward-backward asymmetry in top quark pairs, at 500 GeV, using two beam polarization configurations, in the fully hadronic decay channel. The top quark almost exclusively decays to a b quark and a W boson. The 6 jet final state is analyzed using full detector simulation. Two jets with highest b-tag are taken as b jets and the remaining four jets are used to reconstruct the W s. The identification of the top and anti-top quarks is done by using the vertex charge of the b quark. Precisions on the production cross sections are also calculated. This thesis also includes a chapter on the optimization of the Si-W Electromagnetic calorimeter of the International Large Detector (ILD), one of the two detectors at the ILC. The ECAL of ILD, will consist of alternate layers of Silicon and Tungsten, where Silicon layers are active layers, while Tungsten is passive material. The Silicon layers are divided into wafers, surrounded by guard rings, to avoid the leakage currents. The analysis is focused to optimize the guard ring size. The thesis is divided into 6 chapters. The first chapter gives a brief over view of the Standard Model. The second chapter is dedicated to the theoretical aspects of the top quark physics at the ILC. A detailed description of the ILD and its sub-detectors is given in the 3rd chapter. The 4th chapter presents the studies of the optimization of Si-W ECAL guard ring size. The 5th chapter contains the details of analysis of tt production at ILC, and measurement of the AFBt . The last chapter contains the summary of the results.
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Submitted on : Thursday, February 20, 2014 - 11:24:47 AM
Last modification on : Wednesday, September 16, 2020 - 4:22:21 PM
Long-term archiving on: : Tuesday, May 20, 2014 - 3:05:56 PM

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  • HAL Id : tel-00949818, version 1

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Muhammad Sohail Amjad. Forward-Backward asymmetry in top pair production at the ILC. Other [cond-mat.other]. Université Paris Sud - Paris XI, 2014. English. ⟨NNT : 2014PA112021⟩. ⟨tel-00949818⟩

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