Is the cosmic microwave background telling us that dark matter is weaker than weakly interacting?
Is the cosmic microwave background telling us that dark matter is weaker than weakly interacting?
If moduli, or other long-lived heavy states, decay in the early universe in part into light and feebly interacting particles (such as axions), these decay products could account for the additional energy density in radiation that is suggested by recent measurements of the cosmic microwave background. These moduli decays will …