Speaker
Description
In a secluded dark sector scenario, the connection between the visible and the dark sector can be established through a portal coupling and its presence opens up the possibility of non-adiabatic evolution of the dark sector. Here, we have considered a $U(1)_{L_\mu - L_\tau} \otimes U(1)_X$ extension of the standard model (SM) to study the evolution of a decoupled dark sector in a radiation-dominated Universe. Depending on the values of the portal coupling ($\epsilon$), dark sector gauge coupling ($g_X$), the mass of the dark matter ($m_\chi$), and the mass of the dark vector boson ($m_{Z^\prime}$), we study the temperature evolution of the dark sector as well as the various non-equilibrium stages of the dark sector in detail. Furthermore, we have also investigated the constraints on the model parameters from various laboratory and astrophysical searches. We have found that for $m_{Z^\prime}< 100 \rm MeV$, parameter space for the non-adiabatic evolution of the dark sector is significantly constrained from the observations of beam dump experiments, stellar cooling etc. The bounds from direct detection, and self-interaction of dark matter (SIDM) for the mass ratio $r\equiv m_{\chi}/m_{Z^\prime} = 10^{-3}$ are consistent with the relic density satisfied region and these bounds will be more relaxed for larger values of $r$. However the constraints from the measurement of diffuse $\gamma$-ray background flux and cosmic microwave background (CMB) anisotropy are strongest for $r = 10^{-1}$ and for smaller values of r, they are not significant.
| Secondary category for the parallel session (optional) | Dark Matter Physics |
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