Composite Higgs Theories

Abstract

The Standard Model (SM) of Particle Physics has been extremely successful at describing with amazing accuracy the experimental data available to us today. However, it has well-known limitations, such as being dependent on a large number of arbitrary parameters. Perhaps more importantly, SM is unstable on the electroweak scale, originating the so-called hierarchy problem. A solution to this problem requires new physics on the TeV scale, precisely the energy scale being currently explored at CERN's Large Hadron Collider (LHC) laboratory. In this project, we propose to study extensions to the Standard Model (SM) that describe new physics on the TeV scale. Since the observation of the Higgs boson in 2012, the spectrum of the SM has been completed. Solutions to the hierarchy problem mentioned above are typically divided between two fronts: if the Higgs boson is an elementary particle, supersymmetry must be observable in the TeV scale. Otherwise, the Higgs boson must be a composite state. In this project, we will focus on the latter case. Composite Higgs models generally require the existence of new particles in the TeV scale. Since they predict the Higgs particle to be a Nambu-Goldstone pseudo-boson (pNGB) born from spontaneous breaking of a global symmetry, the new predicted states arise from the new symmetry and appear inevitable. The absence of detection of these states, particularly at the LHC, is one of the issues of composite Higgs models. However, the phenomenology related to the Higgs boson is well defined. This will be the focus of this project: to study the theoretical foundations and phenomenology of composite Higgs models, particularly in contexts whose investigation requires high luminosity. (AU)