Conveners
BSM
- Luca Di Luzio
BSM
- Luca Di Luzio
BSM
- Maria Pestana Da Luz Pereira Ramos
BSM
- Maria Pestana Da Luz Pereira Ramos
Axions and axion-like particles (ALPs) remain compelling dark matter (DM) candidates, provided that the associated Peccei-Quinn (PQ) symmetry breaking scale $f_a$ is sufficiently large to ensure cosmological stability. In this talk, I will explore a novel framework in which ALPs possess flavor-violating (FV) couplings to Standard Model (SM) quarks, allowing them to be produced via freeze-in in...
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...
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...
A novel approach to neutrino oscillations is presented, which is analogous to birefringence. Neutrinos propagate as massless waves undergoing coherent forward flavour changing scattering off the quantum vacuum. The resulting coherent wave obeys a flavour mixing wave equation leading to; the standard oscillation probabilities, a universal effective refractive mass and a unique group velocity...
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...
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...
Even though a fourth chiral generation of fermions is experimentally ruled out, the possibility of extending the SM with vector-like quarks (VLQs), where both chiral components transform the same way under SU(2)_L cannot be excluded. In particular, extensions of the SM involving isodoublet vector-like quarks with standard charges currently stand as the favoured candidate in explaining the...
In curved spacetime, neutrinos experience an extra contribution to their effective Hamiltonian from a four-fermion interaction induced by spacetime geometry, specifically by torsion. This interaction is parity-violating, non-universal, and diagonal in the mass basis, and thus causes neutrino mixing while propagating through a fermionic matter background. It can significantly influence neutrino...
