Relic Abundance of Inert Fermion Doublet Dark Matter

The nature of dark matter (DM) and the mechanism that provides its measured relic abundance\ud are currently unknown and demand physics beyond the Standard Model(SM) of particle physics.\ud In this thesis after giving a brief introduction to the theory of DM we consider a particle physics\ud model in which a vector-like fermion doublet and a triplet scalar are added to the SM spectrum.\ud We also impose Z2 symmetry under which the vector-like fermion doublet is odd, while all other\ud fields are even. As a result the resulting model explains the relic abundance of DM and neutrino\ud masses simultaneously. The mass of DM particle is calculated by taking into account of observed\ud relic abundance of DM. From the observed DM abundance we also obtain a correlation between DM\ud and scalar triplet mass in a certain parameter space