Jump starting the dark sector with a phase transition

We study the possibility to populate dark sector through a phase transition. will consider secluded sectors made of gauge theories, Randall-Sundrum scenarios and conformally coupled elementary particles. These have in common fact that action is approximately Weyl invariant, implying particle production due time dependent background strongly suppressed. In particular no significant takes place during inflation allowing avoid strong isocurvature constraints from CMB. As we show, if scale large compared dynamical mass scale, these automatically undergo transition simplest cases controlled by Hubble parameter. If reheating or radiation abundance obtained can be larger than SM plasma. For transitions completing domination, DM predicted range $10^8$ GeV while values are required for occurring reheating.