The ins and outs of a hidden sector dark matter

by Prof. Michel H. G. Tytgat




In this talk, I will discuss various aspects of dark matter
from a hidden sector (HS). To be concrete, I will focus on dark QED and
kinetic mixing, but the scope is  in principle broader. First, I will
discuss some rather recent results (taking into account the time
dilation caused by Covid-19) that concern the general classification of
production mechanisms for dark matter through a portal, from freeze-in
to freeze-out. Some of these mechanisms lead to a HS that is in thermal
equilibrium but at $T' \neq T$, the latter being the temperature of the
SM particles. This will bring me to a mapping of possible thermal DM
candidates as a function of $T'/T$. An interesting outcome is the
possibility that $T' \gg T$ in the early universe. I will discuss the
history of such a hot dark sector and the possible consequences on  DM