The present Thesis is dedicated to a formal and phenomenological investigation of extensions to two separate sectors of the Standard Model of particle physics (SM): the electroweak sector and the strong sector. The Thesis is divided into two main parts: Part I focuses on the Lee-Wick Standard Model (LW SM), which, by providing a solution to the Hierarchy problem, forms a natural extension of the electroweak sector, while Part II studies the coloron theory, arising from extending the strong sector gauge group.Providing a general introduction about the current state of the SM and the associated challenges in Chapter 1, we proceed in Chapter 2 to analyze the tension between naturalness and isospin violation in the LW SM. Chapter 3 discusses the global symmetries and the renormalizability of LW scalar QED. A first complete calculation of QCD corrections to the production of a massive color-octet vector boson (colorons) is reported in Chapter 4. Finally, we conclude the Thesis in Chapter 5 by summarizing the discussed results and presenting an outlook for future research in the surveyed areas.
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