Speaker
Description
In this talk, we discuss the unphysical behavior that arises when addressing infrared (IR) divergences in particle production rates in cosmology, particularly focusing on axion production coupled to photons. This unphysical behavior manifests as negative production rates for soft axion momentum.
To address this, we calculate the axion production rate at finite temperature. Initially, we use the hard thermal loop (HTL) resummation, which is appropriate for soft momenta. Here, we find that the decay rate remains positive when resumming contributions from both photons. Furthermore, we extend the calculation beyond the HTL approximation, demonstrating that the decay rate remains positive across all momentum scales. This allows us , as well, to identify the deviations between both methods and identify the main contributions to the axion production rate.
