Multiple axions may emerge in the low-energy effective theory of Nature. Generically, the potentials describing these axion fields are non-diagonal, such that a QCD axion might mix with one or more other axion-like-particles. QCD instanton effects render mixing between such states temperature-dependent. We explore how this mass-mixing can impact dark matter production through the misalignment...
In this work, we study the cosmological implications of an initial displacement of the Peccei-Quinn breaking field generated during inflation and the subsequent oscillations of the field around its minimum. These oscillations induce a parametric resonance effect, leading to the exponential growth of perturbations. In our analysis, we employ lattice simulations to investigate the abundance of...
Electromagnetic fields of pulsars can source coherent axion signals at their rotational frequencies, which can be detected by laboratory experiments—pulsarscopes. As a promising case study, we model axion emission from the well-studied Crab pulsar, which would yield a signal at $f \approx 29.6$ Hz and be present regardless of whether the axion contributes to the dark matter abundance. We...
The axion is a hypothetical particle first proposed by Peccei, Quinn, Weinberg and Wilczek to solve the strong CP problem. It was later realized that ultra-relativistic (or "hot") axions thermally produced in the early Universe can contribute measurably to the energy density of the Universe as dark radiation.
The effective number of neutrinos Neff, parametrizing this dark radiation fraction...
In modern cosmology, it is generally assumed that after inflation, the energy of the inflaton field is transferred to radiation through a process known as reheating.
axion-like particle (ALP) have recently gained attention as potential inflaton candidates, as they naturally preserve the flatness of the inflaton potential due to their shift symmetry.
In our work, we explore the reheating...
Axions and Axion-Like-Particles (ALPs) are theoretically well-motivated candidates for dark matter that, due to their large occupation number, can be described as oscillating classical fields. These particles may feature a quadratic interaction with ordinary matter which can modify the field's dynamics in the vicinity of such objects, inducing a very interesting phenomenology. In this talk, I...
The study on lepton flavour violating (LFV) decays in the framework of the non-universal $Z'$ model delves into several fascinating aspects of particle physics. Focusing on the $\Sigma_b$ decays, which are induced by the quark-level transition $b \rightarrow s l_1l_2$, is especially relevant given the existing experimental constraints on LFV processes. The lepton flavour violating decays are...
Flavor deconstruction refers to a framework where the three fermion families are charged under non-universal gauge groups. Such Standard Model extensions have been proven to be capable of explaining flavor hierarchies among charged fermions. Recently, it has been shown that also neutrino anarchy can be realized within flavor-deconstructed models exploiting a seesaw mechanism. The present work...
Building on the realistic U(2) flavor model proposed a few years ago by Linster and Ziegler, we conduct a comprehensive study of possible neutrino mass textures arising from the seesaw mechanism. We identify a set of viable models that provide an excellent fit to low-energy Standard Model flavor observables including neutrinos. Additionally, within an Effective Field Theory framework, we...
Axion-like particles (ALPs) are hypothetical pseudoscalar states that emerge as pseudo-Nambu-Goldstone bosons from the breaking of an approximate global $ U(1) $ symmetry. They appear in several extensions of the Standard Model, offering potential solutions to the strong CP problem, the muon $ g-2 $ anomaly, neutrino mass generation, and dark matter. While most collider-based studies focus on...
We illustrate the potential of a future high-intensity $e^+e^-$ collider running at the $Z$ pole in probing extensions of the Standard Model via precise measurements of flavor-changing processes. We illustrate this potential both within effective field theories and simplified models inspired by current $B$-physics data, focusing on selected flavor-physics measurement projections at FCC-ee, and...
In recent times there has been a growing interest in the search for Axion-Like Particles (ALPs), as well as dedicated data analyses to identify potential evidence of New Physics compatible with an ALP, resulting in constraints on the ALP parameter space. Therefore, it is now the time to present a tool, ALPaca, that facilitates the combination among the different information on ALP...
