Hidden Sector: Three Different Ways

Abstract

This thesis is a compilation of three projects that explore the consequences of different Hidden Sector models in various experimental fields. The first project proposes the Hidden Sector is populated by just one U(1) vector particle. It couples to the Standard Model through kinetic mixing and is responsible for a fraction of Dark Matter density of our Universe. The other two projects look at specic signals from a Hidden Sector with two light scalars coupled to the Standard Model through a Higgs Portal. One of these projects looks at collider consequences and the other projects explores how such Hidden Sector may alter rare decays of B mesons