Etude du couplage du boson de Higgs au quark top dans l'expérience ATLAS

Abstract : The Higgs boson had been unobserved for more than 40 years after its existence was predicted. It was discovered in July 2012 at the LHC (Large Hadron Collider). This discovery offers many new way of testing the limits of the Standard Model which describes our world at the elementary scale. In fact the study of this boson propriety can lead to the observation of New Physic. In this report we will deal with the study of the Higgs boson coupling to the top quark, the heaviest fermion, thanks to the t¯tH final state. Firstly we present the the Standard Model and the phenomenology of the Higgs boson. Thereafter we will justify the choice of looking at the t¯tH with two same sign leptons signature. The next step will be to study the background processes in our study and to test their modelisation. A method to estimate Fakes events from the data in the signal region will be introduced. Finally the sensitivity of our analysis to the signal will be quantified by the computation of an expected median limit on the signal strength with the CLs method.