Physics Beyond the Standard Model

Abstract

Given the shortcomings of the SM described in Sect. 1.6.1 , there have been many efforts to develop a more complete theory which gives rise to the same predictions as the SM at low energies, but incorporates Beyond Standard Model (BSM) physics at higher scales. These range from “Theories of Everything” such as string theory, to “Grand Unified Theories” which unify the three gauge symmetries of the SM in one single gauge symmetry such as $$\text {SU}(5)$$ [1], to simple extensions to the SM gauge group via the inclusion of additional gauge symmetries. In this chapter, we will discuss some of these theories with an emphasis on phenomenology and prospect for discovery at hadron colliders. Section 2.1 introduces the concept of supersymmetry, which posits an additional symmetry of spacetime that can be used to simultaneously solve both the hierarchy problem as well as provide potential dark matter candidates. Section 2.2 then considers alternative scenarios that share similarities with supersymmetric models while evading certain experimental constraints. The phenomenology of these models is described in Sect. 2.3, which leads us to a general overview of long-lived particles in Sect. 2.4. Section 2.5 introduces a simplified class of models that can be used to search for new physics in a model independent way, and a summary of existing constraints on these simplified models is summarized in Sect. 2.6 which provides further motivation for the search presented in this thesis.