In this talk, recent advances in the theoretical description of axions and their interactions are presented. We start by recalling the principle of reparametrization invariance, based on the Goldstone boson nature of the axion. Using this principle as a tool, we discuss first the axion coupling to gauge bosons, and show that they are actually not driven by the anomalies. Then we describe the...
We study the impact of running effects on QCD axion phenomenology. Focusing on variants of DFSZ model, it is possible to suppress simultaneously both the axion couplings to nucleons and electrons, realising the so-called astrophobic axion scenarios, wherein the tight bounds from SN1987A and from stellar evolution of red giants and white dwarfs are greatly relaxed. This suppsression is not...
I will discuss the possibility that the axion Peccei-Quinn symmetry is spontaneously broken after the beginning of inflation. This scenario interpolates between pre-inflationary and post-inflationary axion DM cosmology with significant phenomenological differences from both. In particular, large inflationary fluctuations are produced only at scales not constrained by CMB, avoiding the...
