Phenomenology of Hidden Sector Physics.

Abstract

The existence of a hidden sector, composed of Standard Model (SM) singlets and the interactions between them, is well-motivated by many beyond-the-SM theories, such as GUT theories, string-inspired models and supersymmetry-breaking models. In addition to sharing weak gravity-induced interactions with the visible sector, such SM singlets can couple to the SM Lelds in various other ways. One well motivated hidden sector scenario is that associated with a beyond-the-SM gauge symmetry which is broken via the Higgs mechanism. Although the collider phenomenology of such models is rich and well-documented, few obvious cosmological signatures for them are known. The physics of cosmic strings provides a promising cosmological probe of such hidden sectors, applicable for a general class of symmetry breaking patterns in the hidden sector. This thesis discusses the phenomenology of hidden sectors, including LHC signatures of a hidden sector Higgs boson, the physics of cosmic strings from supersymmetric flat-directions, and dark matter production from a general cosmic string network. We conclude that there are viable prospects for seeing signals of a hidden sector both at the LHC and in cosmological observations.