Primordial Gravitational Waves and ultra-light Dark Matter in a complex singlet extended Standard Model

Sammanfattning: In this thesis, the consequences of extending the internal symmetries of the standard model with a complex singlet scalar field, are investigated in terms of dark matter phenomenology and the possibility of primordial gravitational wave detection utilizing space based laser interferometry. The scalar potential of the model is constructed with a Z2 symmetry, which allows for the retainment of a linear and a quadratic coupling parameter, as well as a stable dark matter candidate, and an additional non-zero vacuum expectation value for the real component of the scalar field. The gravitational wave power spectrum is then calculated by implementing cosmoTransition packages, which identifies the phase transition profiles, tunneling solutions and minimum of the effective potential. The results are discussed and compared to the sensitivity curves of the proposed gravitational wave facilities LISA, BBO and DECIGO.