The axion was originally introduced in the 70s to explain the absence of CP-violating effects in quantum chromodynamics (QCD) through the Peccei-Quinn (PQ) mechanism. It is a pseudo-scalar boson whose mass and couplings to standard model particles are related to the energy scale where the so called Peccei and Quinn symmetry is broken. Several axion models have been proposed, with the common...
We present an axion model based on the Pati-Salam group, where $\mathrm{SU}(3)_{f_R}$ (part of flavor symmetry) has also been gauged. The choice of field content ensures a careful interplay of the two symmetries, such that an accidental global $\mathrm{U}(1)$ Peccei-Quinn (PQ) symmetry emerges. The resulting axion is of high quality for the breaking scale in a certain range, and the model's...
The QCD axion does not need to be a perfect pseudoscalar for solving the strong CP problem. I will discuss a cosmological role of such imperfectness by solving the domain wall problem that prevails in post-inflationary axion models with discrete symmetry. Effective operators, where the Peccei-Quinn field linearly couples to Standard Model particles, can provide a dynamical solution to the...
Axion-like particles (ALPs) are a common feature in many extensions of the Standard Model. However, their stability is not guaranteed by any symmetry, making the consideration of their lifetime crucial when investigating their cosmological consequences. In this talk, I will explore two distinct ALP mass regimes and their corresponding signatures. First, I will focus on sub-eV ALPs, presenting...
A new set of experiments will deliver in the next few years unprecedented sensitivity to Lepton Flavor Violating (LFV) muon decays. Mu3e, proposed at PSI (Switzerland), will focus on observing $\mu\to 3e$ decays, with a projected target of $10^{15}$ muons decaying at rest, and excellent electron/positron track reconstruction. In this talk I will review the current and future statues of these...
