Conveners
Theories of gravity: alternatives to the cosmological and particle standard models: Monday block 1
- Hernando Quevedo (National Autonomous University of Mexico)
- Orlando Luongo (University of Camerino, Physics Division)
- Francesco Pace (University of Torino)
Theories of gravity: alternatives to the cosmological and particle standard models: Monday block 2
- Hernando Quevedo (National Autonomous University of Mexico)
- Orlando Luongo (University of Camerino, Physics Division)
- Francesco Pace (University of Torino)
Theories of gravity: alternatives to the cosmological and particle standard models: Tuesday block 1
- Hernando Quevedo (National Autonomous University of Mexico)
- Orlando Luongo (University of Camerino, Physics Division)
- Francesco Pace (University of Torino)
Theories of gravity: alternatives to the cosmological and particle standard models: Tuesday block 2
- Orlando Luongo (University of Camerino, Physics Division)
- Hernando Quevedo (National Autonomous University of Mexico)
- Francesco Pace (University of Torino)
Description
In the standard model of cosmology, the ΛCDM model based on Einstein’s General Relativity, dark energy is introduced completely ad hoc in order to explain the present acceleration of the universe. The model requires also the introduction of dark matter dominating (by far) ordinary baryonic matter but yet undetected in the laboratory, and it suffers from astrophysical problems. Modifying gravity is a possible alternative, and many such proposals have been presented in recent years. Likewise, the standard model of particle physics is unable to incorporate all the current particle phenomenology and proposed dark matter candidates.
Cosmology and particle physics come together in the early universe and, surprisingly, also in theories and models of the present, accelerating universe. This session is formulated in a wide framework to include several topics related to these problems, and spanning alternative theories of gravity and cosmology, alternatives to the ΛCDM model, quantum field theory applied to gravity, extensions of the standard model of particle physics, and dark energy and dark matter from a particle physics point of view. This session represents the interplay between, and the efforts to match, particle physics and cosmology, giving particular emphasis to the role played by particle quantum field theory in the early and the late universe.
In this work, we investigate the impact of the Dark Energy Spectroscopic Instrument (DESI) 2024 data on dark energy scenarios. Specifically, we analyze three typologies of models, the first in which the cosmic speed up is related to thermodynamics, the second associated with Taylor expansions of the barotropic factor, whereas the third based on ad hoc dark energy parameterizations. In this...
The question of compatibility between our theory of gravity, more or less along the line of General Relativity, and basic notions of quantum physics has been a major concern. We focus, in particular, on an exact Weak Equivalence Principle and the notion of the momentum observable for a particle as a vector quantity with an invariant magnitude as given through the metric. Contrary to the...
We discuss the entanglement entropy for a massive Klein-Gordon field in two Schwarzschild-like quantum black hole spacetimes, also including a nonminimal coupling term with the background scalar curvature. To compute the entanglement entropy, we start from the standard spherical shell discretisation procedure, tracing over the degrees of freedom residing inside an imaginary surface. We...
We reflect on the possibility of breaking the diffeomorphism (Diff) invariance in the gravitational couplings of matter down to only transverse diffeomorphisms (TDiff), and study the consequences on a scalar field theory. We then explore the possibility of restoring the full Diff invariance preserving the locality of the theory by the introduction of an additional vector field. From the...
We explore a model in modified $f(R)$ gravity where the modification in geometrical part of the Einstein-Hilbert action leads to complete elimination of the need for dark matter and dark energy, both. This is specifially obtained by the scalar fields induced in the Einstein's gravity whose dynamical oscillations account for the effects (otherwise attributed to dark matter and dark...
We discuss general solutions of the Einstein-Cartan theory sourced by a cosmological perfect fluid composed of particles with intrinsic spin. In the considered model, the metric tensor is described by a general FLRW solution, however, the Weyl tensor might not vanish. The coupling between the intrinsic spin and the Weyl tensor excludes spatially closed solutions, and the universe must either...
We here explore a specific class of scalar field, dubbed quasi-quintessence which exhibits characteristics akin to ordinary matter. Specifically, we investigate under which conditions this fluid can mitigate the classical cosmological constant problem. We remark that, assuming a phase transition, it is possible to predict inflationary dynamics within the metastable phase triggered by the...
Particle detector models have been recently proven to be an effective mean to know how curved spacetimes affect quantum systems. For example, particles generated by the Unruh effect could be detected by an accelerating system and can provide a reliable communication of quantum messages, usually prevented by the no-cloning theorem. Motivated by this fact, we propose a quantum communication...
This study focuses on constructing physical model of spherically
symmetric systems incorporating electromagnetic fields within the
framework of f (Q) gravity. To achieve this, we derive the field equations corresponding to f (Q) gravity in the presence of anisotropic matter, and then connect the interior space-time with the exterior Reissner
Nordstrom metric to determine the constants...
We propose a model-independent Bézier parametric interpolation to alleviate the degeneracy between baryonic and dark matter abundances by means of intermediate-redshift data. To do so, we first interpolate the observational Hubble data to extract cosmic bounds over the (reduced) Hubble constant, h0, and interpolate the angular diameter distances, D(z), of the galaxy clusters, inferred from the...
We investigate inflationary particle production, focusing in particular on the role of inflaton fluctuations and the corresponding geometric particle production arising from spacetime perturbations. We analyze both small and large-field models, in agreement with experimental observations, also discussing nonminimal coupling to the scalar curvature of spacetime. Geometric production is then...
Cosmology is mainly based on the Friedmann's equations assuming Isotropy and Homogeneity of the Einstein spacetime, starting from the Friedmann-Lemaître-Robertson Walker metric. Introduction of an ad hoc Cosmological Constant allows to model phenomenologically the so-called Dark Energy for explaining the acceleration of the Universe expansion discovered by Riess et al. and Permutter et al....
To describe the dark side of the Universe, we adopt a novel approach where dark energy is explained as an electrically charged majority of dark matter. Dark energy, as such, does not exist. The Friedmann equation at the present time coincides with that in a conventional approach, although the cosmological "constant" in the Electromagnetic Accelerating Universe (EAU) Model shares a time...
Singularities in Newton's gravity, in general relativity (GR), in Coulomb's law, and elsewhere in classical physics, stem from two ill conceived assumptions that, a) there are point-like entities with finite masses, charges, etc., packed in zero volumes, and b) the non-quantum assumption that these point-like entities can be assigned precise coordinates and momenta. In the case of GR, we argue...
The present-day standard model of cosmology, Lambda-CDM, gives us a representation of a cosmos whose dynamics is dominated by gravity (general relativity) with a finite lifetime, large scale homogeneity, expansion and a hot initial state, together with other dark elements necessary to avoid certain inconsistencies with observations. There are however some models with characteristics that are...
In this talk I will present the evolution of perturbations in a sub-class of Horndeski models characterised by shift symmetry, considering a very general parametrisation of the background. I will show how the free background parameters affect the evolution of the perturbations and present results on the halo mass function and how we can use it to distinguish these models from the standard LCDM...
This work aims to investigate the impact of spatial curvature in modified gravity models, specifically within the Horndeski framework. Typically overlooked in the literature due to the spatial flatness assumed in the ΛCDM model, this study aims to fill this gap. The ΛCDM model, rooted in General Relativity (GR), is in good agreement with observational data, but faces problems with cosmological...
We consider the gravitational field outside a static, spherically symmetric source in the context of a general $f(R)$ extension of General Relativity. We study the modified Einstein equations (EE), which involve the two free potentials of the metric together with $f(R)$ and its derivative $\phi = \frac{\partial f}{\partial R}$, without making any preliminary assumption on $f$ as a function of...
Abstract: Dust is considered to be the simplest form of matter composed of pressureless, radiation and is abundant in galaxies, clusters and superclusters in a cosmological context. It has also been shown that stars are encompassed by these radiating pressureless particles which make up the atmosphere of the star. The gravitational behaviour of these pressureless fluid distributions are...
We evaluate the effects of repulsive gravity using first order geometric invariants for regular black holes. We compare the repulsive regions with the predictions got from singular solutions. Notable characteristics and pathologies of regular black holes are thus emphasised. To heal the potential incompleteness of regular solutions, we construct alternative regular solutions. Implications and...
