Speaker
Description
The preferred axion models are a set of minimal QCD axion models that abide by standard cosmological constraints in the post-inflationary PQ breaking scenario. It turns out that some of these models predict a period of early matter domination. This is driven by the additional particle content of the models. I will discuss how this actually enables a greater number of models to be consistent with current observations and alters the axion dark matter mass range. On the other hand, the decay products of the new heavy particles may contribute to the number of relativistic degrees of freedom during recombination. This allows us to make concrete predictions and distinguish against preferred axion models, even in scenarios where early matter domination doesn't occur.
