High-scale Mirror Standard Model Dark Matter, Dark Phase Transitions and Gravitational Waves Implications

Author(s)

Oikonomou, V.K.

Abstract

We consider a scenario for dark matter in the Universe, according to which the dark matter sector is comprised by a dark Standard Model sector which interacts only gravitationally with the ordinary Standard Model sector. This dark Standard Model sector is assumed to have the same symmetries as the ordinary Standard Model, with the couplings and the scale of the mirror Standard Model sector being different than the ordinary Standard Model sector. Specifically, the scale of the mirror Standard Model sector will be assumed to be quite higher compared to the ordinary Standard Model. Also the Yukawa couplings among the mirror Higgs and the mirror fermions are assumed to be different from those of the Standard Model and we examine the effects of the different scale and of the different Yukawas on the evolution of the Universe. As we show, a mirror world phase transition occurs at high temperatures of the baryonic Universe, which can be first order or second order, depending on the scale of the Universe and the Yukawa couplings. These are dark phase transitions which occur quite earlier than the real world Standard Model electroweak phase transition. The case of a second order phase transition is quite interesting phenomenologically, since it can potentially have a direct imprint on the spectrum of stochastic gravitational waves for frequencies probed by the future gravitational wave detectors. Also we examine whether this mirror dark matter world can form atoms and as we show in some scenario the high scale mirror dark matter can have both atomic and subatomic particle components. We also give an approximation of the total equation of state of high scale mirror DM and we discuss how high scale mirror DM can reconcile contradicting observations like the Bullet cluster and the Abell 520 cluster.

Figures

Caption

The effective potential of the high scale mirror SM for at exactly the critical temperature $T_c\sim 10931\,$GeV. Notice the strong fluctuations of the effective potential at the origin (upper plots) and the fact that the phase transition is second order, which can be better seen in the bottom plot. Also notice in the upper two plots the absence of a barrier, a feature that indicates a potential second order phase transition.

Caption

The effective potential of the high scale mirror SM for at exactly the critical temperature $T_c\sim 10931\,$GeV. Notice the strong fluctuations of the effective potential at the origin (upper plots) and the fact that the phase transition is second order, which can be better seen in the bottom plot. Also notice in the upper two plots the absence of a barrier, a feature that indicates a potential second order phase transition.

Caption

The effective potential of the high scale mirror SM for at exactly the critical temperature $T_c\sim 10931\,$GeV. Notice the strong fluctuations of the effective potential at the origin (upper plots) and the fact that the phase transition is second order, which can be better seen in the bottom plot. Also notice in the upper two plots the absence of a barrier, a feature that indicates a potential second order phase transition.

Caption

The effective potential of the high scale mirror SM for various temperatures near the critical temperature $T_c^{'}\sim 10931\,$GeV. The phase transition is a typical second order phase transition.

Caption

The abundance of mirror DM particles as a function of the mirror Higgs self-coupling $\lambda_{H'}$.

Caption

The zero temperature effective potential of the high scale mirror SM for scenario I.

Caption

The high temperature effective potential for the mirror SM for the scenario II, for various temperatures near the critical temperature.

Caption

The $h^2$-scaled gravitational wave energy spectrum for scenario I, with the deformed background EoS having the value $w=0.25$ corresponding to frequencies probed by LISA, BBO and DECIGO $k_s=10^{10}$Mpc$^{-1}$. We considered a standard red-tilted inflationary era, with tensor spectral index being $n_{\mathcal{T}}=-r/8$ and the tensor-to-scalar ratio being $r=0.003$ and three distinct reheating temperatures $T_R=500\,$GeV, $T_R=10^7\,$GeV, and $T_R=10^{12}\,$GeV.

Caption

The $h^2$-scaled gravitational wave energy spectrum for scenario I, with the deformed background EoS having the value $w=0.65$ corresponding to frequencies probed by LISA, BBO and DECIGO $k_s= 10^{10}$Mpc$^{-1}$. We considered a standard red-tilted inflationary era, with tensor spectral index being $n_{\mathcal{T}}=-r/8$ and the tensor-to-scalar ratio being $r=0.003$ and three distinct reheating temperatures $T_R=500\,$GeV, $T_R=10^7\,$GeV, and $T_R=10^{12}\,$GeV.

Caption

The $h^2$-scaled gravitational wave energy spectrum for scenario I, with the deformed background EoS having the value $w=0.85$ corresponding to frequencies probed by LISA, BBO and DECIGO $k_s= 10^{10}$Mpc$^{-1}$. We considered a standard red-tilted inflationary era, with tensor spectral index being $n_{\mathcal{T}}=-r/8$ and the tensor-to-scalar ratio being $r=0.003$ and three distinct reheating temperatures $T_R=500\,$GeV, $T_R=10^7\,$GeV, and $T_R=10^{12}\,$GeV.