Hidden sectors and a multi-temperature universe

Understand

A variety of supergravity and string based models contain hidden sectors which can play a role in particle physics phenomena and in cosmology.

• In this note we discuss the possibility that the visible sector and the hidden sectors in general live in different heat baths.
• Further, it is entirely possible that dark matter resides partially or wholly in hidden sectors in the form of dark Dirac fermions, dark neutralinos or dark photons.
• A proper analysis of dark matter and of dark forces in this case requires that one deals with a multi-temperature universe.