• ALPs
• Anomalous magnetic moment
• Asymmetric DM
• Axion
• Dark matter phenomenology
• Dark matter theory
• DFSZ models
• Direct detection
• EFT
• Flavour physics
• Flavoured axions
• Strong CP problem
• XENON1T

It was recently found that electron recoils induced by non-relativistic DM interactions can fit well the recently reported XENON1T excess if they are mediated by a light pseudoscalar particle in the MeV mass range.
One of the main goal of this thesis is to find a UV model of DM and mediator at the GeV scale that is able to explain the excess and, at the same time to adress other relevant issues in SM.
A tantalizing option for the mediator is the QCD axion that, in the mass range of a few MeV, is generally known as a ”visible” axion. However, this class of models is subject to a variety of phenomenological bounds (quarkonia decays, kaon decays and electron beam dump experiments) which rule out the original proposal. We will see that it is actually possible to relax the constraints on visible axion models by assuming flavour non-universal couplings to SM fermions, such that the resulting axion is pionphobic. We study, in a model independent way, the phenomenology of this class of models and we also find that the Anomalous Magnetic Moments (AMM) for both the electron and muon can be simultaneously explained.
Armed of the model independent analysis, we then construct a possible UV DFSZ-like model that is able to generate flavour non-universal couplings of the axion with SM fermions of the required size, and at the same time to make the axion a portal to a Dark Sector. One of the consequences of this construction is to generate additional couplings and therefore enrich the already interesting phenomenology of the model. In particular, the unavoidable couplings of DM with light quarks and gluons will induce elastic DM-nucleus collisions that, by using the XENON1T nuclear recoils, further constraints the parameter space.