Recherche du boson de Higgs du Modèle Standard produit par fusion de bosons vecteurs et se désintégrant en deux photons dans l’expérience ATLAS auprès du LHC

In this thesis, the search for the Standard Model Higgs boson produced through Vector Boson Fusion and decaying to two photons, using the ATLAS detector at the LHC, is presented. After introducing the theoretical context relevant to Higgs boson searches at the LHC, a description of the ATLAS detector design and performance is given. Key experimental aspects of photon physics, such as the reconstruction and identification, are discussed. A special accent is put on photon trigger studies. Global improvements to the Higgs boson to di-photon analysis strategy and categorization of events are then presented. In particular, we describe the design and implementation of a cut-based search for the Higgs boson produced through the Vector Boson Fusion (VBF) process. These improvements had a decisive impact in the discovery of a new resonance by the ATLAS Collaboration in 2012. An alternative inclusive search for $H\to\gamma\gamma$, fully based on a multivariate technique (MVA), is also reported. Finally, an improved MVA is used to search for the VBF production of the Higgs boson in the di-photon channel, and is applied to the full LHC Run I dataset. This analysis has enhanced the sensitivity to VBF by about 30%. It contributed greatly to the first experimental evidence for the VBF production, which is one of the most important results published by ATLAS in Higgs boson physics.