We study the quantum field theory of neutrino mixing in the presence of spacetime torsion. We derive new oscillation formulae for the constant torsion background, displaying the spin dependence of the oscillation probability
Extended theories of gravity have been extensively investigated during the last thirty years, aiming at fixing the infrared and ultraviolet shortcomings of General Relativity and the associated ΛCDM cosmological model. Recently, non-local theories of gravity have drawn increasing attention due to their potential to ameliorate both the UV and IR behaviour of the gravitational interaction....
Gravitational Lensing is the effect for which light rays are deflected by a gravitational field. In presence of a black hole acting as a lens, photons can wind several times around it before fleeing towards the observer. This creates two infinite sequences of images of a given source with decreasing magnitude, asymptotically approaching the border of a zone that will remain obscure called...
We show how in phenomenological approaches to quantum gravity associated with fundamental length or energy scales, the propagation of particles is associated with dispersion relations characterized by additional terms or non-linearities. Deviations from ordinary dispersion relations provide essential signatures of Planck-scale physics and induce quantum gravitational effects, as modified...
We present the relativistic version with spin of quantum mechanics written in terms of hydrodynamic variables: in this way the Dirac theory is converted into a form that does not involve the selection of any representation nor the choice of any frame. Such a re-formulation is necessary to visualize concepts of quantum mechanics, and it is also important for No-Go theorems where a choice of...
The analysis of quantum states in non-smooth spacetimes has two main motivations. First, there are several models of physical phenomena that require spacetime metrics with finite regularity. These include models of gravitational collapse, astrophysical objects and general relativistic fluids. Second, the well-posedness of Einstein’s equations, viewed as a system of hyperbolic PDE requires...
Making use of the 1 + 3 covariant formalism, we show explicitly the effect that nonmetricity has on the dynamics of the universe. Then, using the Dynamical System Approach, we analyze the evolution of Bianchi type-I cosmologies within the framework of f(Q) gravity. We consider several models of function f(Q), each of them manifesting isotropic eras of the universe, whether transitional or not....
I discuss recent developments in the analysis of the conformal backreaction exerted by conformal matter on the external classical gravitational metric. The approach relies on a reconstruction of the effective action exploiting conformal symmetry in momentum space.
Conformal symmetry imposes strong constraints on correlation functions. Indeed, the general structure of 2 and 3-point functions is completely fixed up to a few constants by such symmetry. These results are usually obtained in position space in contrast with general QFT where Feynman diagrams are typically computed in momentum space. I will discuss how conformal symmetry completely determines...
We investigate the influence of a time-varying spacetime background on the vacuum polarization of a massless quantum field confined to a Casimir cavity. The background is modelled as an anisotropic Bianchi-I spacetime, in which small time-dependent perturbations around the flat spacetime are vanishing in the far past and future. The spacetime admits asymptotic Minkowskian regions, thus...
Recently, the cosmographic approach has gained considerable interest as a model-independent technique that can describe the recent expansion of the universe. In fact, given only the observational assumptions of the cosmological principle, it makes it possible to study such an evolution without assuming a specific cosmological model. In this talk I will show some of the most promising lines of...
One of the most debated issues in astrophysics is the discrepancy, which ranges between 4 to 6 sigma, between the locally estimated value of the Hubble constant using the SNeIa distance scale calibrated with Classical Cepheids and the cosmological value derived from Cosmic Microwave Background Radiation (CMBR). This problem is commonly referred to as the Hubble constant tension and represents...
We discuss the generalization of gravitational energy-momentum pseudo-tensor to Extended Theories of Gravity, in particular to higher-order theories in curvature invariants. This result is achieved by imposing that the local variation of gravitational action of any order vanishes under rigid translations. We also prove that this tensor, in general, is not covariant but only affine, that is, it...
In this talk, I give a definition for the phenomenological tomogram of the universe. I introduce the theoretical classical and quantum tomograms. I show how we could investigate the primordial quantum state of the universe from the possible deviations of the phenomenological tomogram from the classical tomogram.
QGSKY - Highlights on Catania Unit research work
When the Higgs effective potential $V_{eff}(\phi)$ and/or the vacuum energy $\rho$ are derived from higher dimensional theories with compact extra dimensions and non-trivial boundary conditions (as in the case of the Scherk-Schwarz SUSY breaking mechanism), the usual calculations lead to the conclusion that these quantities are UV-insensitive. Based on the finite result for $\rho$ and on the...
Non-linear electrodynamics (NLED) is a generalization of Maxwell’s electrodynamics for strong fields. It could have significant implications for the study of black holes and cosmology and have been extensively studied in the literature, extending from quantum to cosmological contexts. Recently, its application to black holes, inflation and dark energy has caught on, being able to provide an...
