Thesis:

Topics on composite Higgs

A currently open question is whether the Higgs boson particle is truly elementary (i.e. pointlike), down to distance scales much shorter than the Electroweak scale, or if, on the contrary, it is a composite bound state of more fundamental degrees of freedom, whose physics should be revealed at energies not far above the weak scale. In either case the discovery of this scalar particle was truly remarkable. If it turns out to be elementary, it would be the first and only known example of this kind in nature. On the other hand, if it turns out that the Higgs boson is a composite state arising from some underlying strong dynamics, we would be in a situation that also presents new characteristics compared to other known composite scalars. We elaborate on this last possibility in the present thesis. This thesis aims to be a pedagogical and self-contained theoretical review of some of the most relevant aspects of general composite Higgs theories. It begins with section 1 reviewing the basics of the Standard Model. Section 2 reviews some important characteristic of the Higgs boson: its most important decay and production channels, as well as its radiative corrections. Section 3 explains the hierarchy problem, and presents the best-known approaches that address this problem. In section 4 we explain the composite sector of a composite Higgs theory and proceed to present the CCWZ prescription, a fundamental tool when it comes to understand the low-energy and confinement regime of a strong dynamic. Section 5 present the elementary and composite sectors. In section 6 we introduce extra spin-0 and spin-1 resonances. Finally, in section 7 we introduce the phenomenology of a particular composite Higgs model analyzed in Ref. [123] and in which the author of the thesis was part.