Top quark studies at a Linear Collider

Abstract

The International Linear Collider (ILC) is a proposed e+e collider with a center-of-mass energy of 500 GeV, aimed at precision measurements, e.g. of a light Higgs-like boson that has been discovered recently at the Large Hadron Collider. Its detectors require the use of ne grained calorimeters to achieve the desired precisions. This thesis presents the study of top quark pair production at the ILC. The semileptonic decay of the top quark is studied with a full simulation of the proposed detector for the ILC (called ILD) at center-of-mass en- ergy ps = 500 GeV and integrated luminosity L = 500 fb1 (expected for a 4 years running). The detector performance permits to reach e ciencies larger than 70% in nding top events with a purity larger than 95%. This translates into a relative accuracy of about 1% top forward-backward asymmetry At FB with electrons(positrons) polarizations of 80%(30%). The aim of this thesis is to obtain the errors of the top quark couplings to the Z and the bosons, using observables like At FB, cross-sections ( ) or helicity angle ( hel).