O modelo padrão das interações eletrofracas: fundamentos e fenomenologia

Abstract

The theory of electroweak interactions has been systematically verified through experiments over the past 40 years. Its confirmations began to emerge in the late 1970s with the detection of the W± and Z 0 gauge bosons, culminating in the discovery of the Higgs boson in 2012. Due to all its predictability, the theory was elevated to the status of Standard Model of Electroweak Interactions. This event justifies the importance of studying its theoretical foundations and its phenomenology. In this dissertation, we will study in detail the fundamentals of the theory of electroweak interactions, including field theory 2 , gauge theory and the Higgs mechanism. The Standard Model (MP) has based on field theory and the Higgs mechanism and is guided by gauge principles. Fermions play a fundamental role in the model in question, constituting the sector of matter and can be classified into leptons or quarks. In this sense, we will carry out a study of the MP, analyzing each sector individually and, in terms of phenomenology, will be examined the model contributions to the reaction e +e − −→ W+W−. Despite the experimental success achieved by MP, its inability to explain mass of neutrinos, whose massive nature was proven in experiments of oscillations between neutrinos in 1998, highlights the need for an extension of the model. In the second part in this dissertation, the extension of the MP that incorporates the Seesaw Mechanism of the Type-I, responsible for generating the small masses of neutrinos.