Preliminary Study On The Correlation Between First Order Phase Transition And Dark Matter

In this paper,we have studied two dark matter production mechanisms in detail,the freeze-out mechanism and the freeze-in mechanism.The dark matter produced through the freeze-out mechanism is WIMP dark matter.In the freeze-out situation,dark matter and Standard Model particles are in thermal equilibrium at first.When the production rate of dark matter is less than the expansion rate of the universe,dark matter will"freeze-out"and then evolve into the present relic abundance of dark matter.The dark matter produced through the freeze-in mechanism is FIMP dark matter.The interaction between the dark matter in the freeze-in situation and the standard model particles is very weak,and it has not been able to achieve thermal equilibrium.The interaction between dark matter and Standard Model particles in the Freeze-in mechanism is very weak,and it is difficult to search for FIMP dark matter signals in experiments on the ground.Phase transition will have an impact on FIMP dark matter.If we find the correlation between phase transition and dark matter,we can search for dark matter models through gravitational wave detection,so as to limit the parameter space of dark matter.In the standard model,the phase transition is a cross-over process,and the first-order phase transition cannot be achieved.We can extend the standard model to achieve a first-order phase transition.This paper mainly studies the Z₃ model.The phase transition process of the spontaneous symmetry breaking of Z₃ will form domain walls(DW,Domain Walls).During the entire phase transition,the phase transition will generate gravitational waves in the frequency range of 10^-5 to 10³ Hz.Space-time oscillations caused by domain wall decay will generate gravitational waves in the frequency range of10^-10 to 10^-5Hz.The gravitational waves generated by domain wall decay can be detected by the pulsar timing array and the future SKA(Square Kilometer Array).