A new approach to the cosmological moduli problem

A generic byproduct of many theories beyond the Standard Model is the appearance of light scalar fields known as moduli. These moduli should be copiously produced in the early universe but have dangerously long lifetimes, leading to their excessive domination of the late-time energy density — an issue known as the “cosmological moduli problem”. In this talk, we discuss a number of new effects which have direct relevance for the cosmological moduli problem and which, depending on circumstances, can either unexpectedly amerliorate it or worsen it, often by many orders of magnitude. As described more fully in Ref. [1], these effects arise in theories containing multiple moduli which mix amongst themselves in the presence of a mass-generating phase transition.