arXiv subjects

Giuseppe Meluccio

Publications and source records attributed to Giuseppe Meluccio.

14 recordsLinked to original sources

arXiv2026

DESI and Dynamical Dark Energy from Extended Pre-geometric Gravity

We consider the simplest quadratic extension of MacDowell--Mansouri pre-geometric gravity that preserves the topological pre-volume-form symmetry. Upon symmetry breaking, the theory reduces to $(\mathrm{Lovelock})^2$ gravity and admits a Galileon-like Horndeski scalar-tensor representation. The gravitational Higgs mechanism relates the Gauss--Bonnet coupling to the bare cosmological constant, while the quadratic correction elevates the gravitational $θ$-angle to a dynamical gravi-axion whose ultra-light mass scale can drive late-time acceleration. We confront the Jordan-frame background with DESI DR2 baryon-acoustic-oscillation measurements and an auxiliary six-point compressed growth diagnostic. A transient dark-energy response localized near $H\simeq m_b$ ($m_b$ the effective gravi-axion mass) reproduces the fitted expansion and its BAO-distance predictions and becomes negligible at high redshift. For the full linear calculation, we combine a smooth positive-density representative of this response class with explicitly imposed GR-like tensor and local sectors, together with the parameterized post-Friedmann prescription. The resulting gravi-axion benchmark exhibits a transient effective phantom crossing and admits a regular full linear CAMB evolution. Its separate likelihood contributions are promising relative to those obtained from the flat-$Λ$CDM baseline for the same data set. These results establish the dynamical gravi-axion framework, dual to MacDowell--Mansouri pre-geometric gravity, as a viable effective quantum-gravity inspired description of late-time cosmology, motivating further investigation into its fundamental origin and perturbative consistency.

gr-qc↗

arXiv2026

Emergence of Gravity's Dynamical and Topological Sectors from Pre-geometry

We identify the complete set of fundamental building blocks for a 4D pre-geometric theory of gravity. Based on a gauge theory of $SO(1,4)$ or $SO(2,3)$ coupled to a Higgs-like field under the rigid constraint of general covariance in the unbroken phase, these building blocks - $\mathcal{L}_\text{MM}$, $\mathcal{L}_\text{W}$, $\mathcal{L}_{J}$, $\mathcal{L}_θ$ and $\mathcal{L}_\vartheta$ - constitute the minimal generating set of independent field monomials from which any pre-geometric action, including arbitrary functionals thereof, can be constructed. While the most general pre-geometric theory can extend beyond linear combinations, these five irreducible invariants serve as the 'atomic' constituents of all possible pre-geometric dynamics. Upon spontaneous symmetry breaking, they collectively generate an emergent gravitational theory consisting of the Einstein-Hilbert action, the cosmological constant term and all 4D topological invariants: the Gauss-Bonnet, Pontryagin, Holst and Nieh-Yan terms. The unification of gravity's dynamical and topological sectors from a common pre-geometric source represents the central result of this work. We also uncover a see-saw mechanism linking the Planck mass and the cosmological constant, as well as several novel relations for the coupling constants of the topological sector, inclusive of the Barbero-Immirzi parameter. This framework establishes the pre-geometric foundations from which all aspects of gravitation can dynamically emerge, providing a unified starting point for quantum gravity, dark energy phenomenology and the study of topological phases in gravitational theories.

gr-qc↗

arXiv2026

The Pre-geometric Origin of Geometric Trinity of Gravity

The so-called Geometric Trinity of Gravity is based on three distinct geometric features of spacetime, i.e.\ curvature, torsion and non-metricity, which give rise to equivalent dynamics for General Relativity (GR), Teleparallel Equivalent of General Relativity (TEGR) and Symmetric Teleparallel Equivalent of General Relativity (STEGR). Pre-geometric gravity, on the other hand, offers a unifying framework from which all metric-affine theories can emerge. Starting from a gauge formulation \textit{à la} Yang--Mills with a Higgs-like field, a mechanism of spontaneous symmetry breaking can give rise to an effective metric as well as to the classical dynamics of the gravitational field. In particular, the emergence of gravity in the spontaneously broken phase is shown to be consistent with all the different formulations of the Geometric Trinity of Gravity, in terms both of actions and of gauge choices for the affine connection. This general result is achieved by deriving and analysing suitable expressions in the unbroken phase for pre-geometric actions and for pre-geometric gauge-fixing conditions respectively.

gr-qc↗

arXiv2026

Non-local gravity effects in cosmological dynamics probed by IceCube/KM3NeT signals and dark matter relic abundance

Non-local gravity terms have a relevant role in determining the cosmological dynamics. Here we consider curvature- and torsion-based cosmological models where non-local terms can be ``scalarised'' and then reduced under the standard of scalar-tensor gravity. In this context, we study the role of non-local cosmology with regards to the recent results reported by the IceCube/KM3NeT experiments, which revealed high-energy astrophysical neutrino fluxes up to energies of $220$\,PeV. Specifically, we consider the four-dimensional operator $y_{αχ}\bar L_αHχ$ in order to explain both the neutrino rate result and the abundance of dark matter in the Universe, provided that the cosmological background evolves according to non-local gravitational field equations. We show that different dynamical systems representing the evolution of the Universe can be highly sensitive to the parameters of non-local gravity at energies probed by IceCube/KM3NeT. In particular, we adopt power law solutions inferred by the existence of Noether symmetries in non-local cosmological models.

gr-qc↗

arXiv2026

Emergent Gravity from Topological Quantum Field Theory: Stochastic Gradient Flow Perspective away from the Quantum Gravity Problem

We propose a scenario according to which the ultraviolet completion of General Relativity is realized through a stochastic gradient flow towards a topological BF theory. Specifically, we consider the stochastic gradient flow of a pre-geometric theory proposed by Wilczek. Its infrared limit exists, and corresponds to a fixed point where stochastic fluctuations vanish. Diffeomorphism symmetries are restored in this limit, where the theory is classical and expressed by the Einstein-Hilbert action. The infrared phase then corresponds to the classical theory of General Relativity, the quantization of which becomes meaningless. Away from the infrared limit, in the pre-geometric phase of the stochastic gradient flow, the relevant fields of the Wilczek theory undergo stochastic fluctuations. The theory can be quantized perturbatively, generating corrections to the classical Einstein-Hilbert action. The stochastic gradient flow also possesses an ultraviolet fixed point. The theory flows to a topological BF action, to which non-perturbative quantization methods can be applied. Two phase transitions occur along the thermal time dynamics, being marked by: i) the breakdown of the topological BF symmetries in the ultraviolet regime, which originates the pre-geometric phase described by the Wilczek theory; ii) the breakdown of the parental symmetries characterizing the Wilczek theory, from which General Relativity emerges. The problem of quantizing the Einstein-Hilbert action of gravity finally becomes redundant.

gr-qc↗

arXiv2026

$\mathcal{H}$olographic $\mathcal{N}$aturalness and Information See-Saw Mechanism for Neutrinos

The microscopic origin of the de Sitter entropy remains a central puzzle in quantum gravity related to the cosmological constant problem. Within $\mathcal{H}$olographic $\mathcal{N}$aturalness, we propose this entropy is carried by light, coherent degrees of freedom - "hairons" - emerging as moduli of gravitational instantons on orbifolds. From the Euclidean de Sitter instanton ($S^4$), we construct a new class of orbifold gravitational instantons, $S^4/\mathbb{Z}_N$, where $N$ corresponds to the de Sitter entropy. The moduli space dimension scales linearly with $N$, and we identify these moduli with hairon fields. A $\mathbb{Z}_N$ symmetry from Wilson loops ensures mode distinguishability, yielding the correct entropy. Hairons acquire a mass of the order of the Hubble scale with negligible interactions, suggesting the de Sitter vacuum is a Bose-Einstein condensate of these excitations. We then unify the neutrino mass generation with the cosmological constant via gravitational topology. The small neutrino mass emerges naturally without new physics beyond the Standard Model. The gravitational Chern-Simons structure and anomaly force a topological Higgs mechanism, leading to neutrino condensation via $S^4/\mathbb{Z}_N$ instantons. The topological degrees $N \sim M_\text{P}^2/Λ\sim 10^{120}$ provide both a holographic entropy counting and a $1/N$ information see-saw mechanism for neutrino masses. Predictions: (i) neutrino superfluid condensation forming Cooper pairs below meV as cold dark matter; (ii) resolution of the strong CP problem via a QCD composite axion; (iii) time-varying neutrino masses tracking th dark energy evolution; (iv) signatures in astroparticle physics, ultra-high-energy cosmic rays and high magnetic field experiments.

hep-ph↗

arXiv2026

$\mathcal{H}$olographic $\mathcal{N}$aturalness and Pre-Geometric Gravity

The cosmological constant (CC, $Λ$) problem represents a remarkable discrepancy of about 120 orders of magnitude between the observed dark energy and its natural expectation from quantum field theory. This paper synthesizes two paradigms - holographic naturalness ($\mathcal{HN}$) and pre-geometric gravity (PGG) - to propose a unified resolution. The $\mathcal{HN}$ framework posits that CC stability is not a matter of radiative corrections but of quantum information and entropy. The large entropy $S_\text{dS}\sim M_\text{P}^2/Λ$ of the de Sitter (dS) vacuum acts as an entropic barrier, exponentially suppressing destabilizing quantum transitions. This explains why the universe remains in a high-entropy, low-CC state. We embed this within PGG, where spacetime geometry and the Einstein-Hilbert action emerge dynamically from the spontaneous symmetry breaking SO($1,4$)$\rightarrow$SO($1,3$), driven by a Higgs-like field $ϕ^A$. Both $M_\text{P}$ and $Λ$ are generated from more fundamental parameters. Crucially, we establish a direct correspondence between the VEV $v$ of the pre-geometric Higgs field and the de Sitter entropy: $S_\text{dS}\sim v$ (or $v^3$). Thus, the field generating spacetime also encodes its information content. The smallness of $Λ$ follows directly from the largeness of $S_\text{dS}$, a manifestation of a large $v$. The CC is stable because a large-entropy state's decay is exponentially suppressed. Our study shows new semi-classical quantum gravity effects dynamically generate "hairons", particles whose mass is tied to the CC. The instability of the dS space, driven by a condensate evolution, points to a dynamical origin for dark energy. This framework inextricably links the emergence of geometry, the hierarchy of scales and the quantum-information structure of spacetime, providing a novel path toward solving the CC problem.

hep-th↗

arXiv2026

Solution to the Cosmological Constant Problem from Pre-geometric Gravity

We present a novel solution to the cosmological constant (CC) problem that requires no fine-tunings nor anthropic reasoning. In pre-geometric gravity (PGG), spacetime emerges from the spontaneous breaking of a fundamental gauge symmetry. This mechanism dynamically generates general relativity while also revealing a deep connection: the topological Gauss-Bonnet coupling of the theory scales precisely as the de Sitter entropy, an enormous number which reflects the information content of our universe. This coupling acts as a gravitational $θ$-angle parameter, forcing the CC to become quantized into discrete topological sectors. The symmetry-breaking dynamics naturally selects the sector corresponding to the observed vacuum energy. The selected vacuum state is stabilized by the extremely large potential barrier of the pre-geometric Higgs field, which effectively seals it off from quantum tunneling transitions to other topological sectors. The PGG framework thus provides a dynamical explanation for the smallness of the CC, linking gravity, topology and quantum information in a unified picture.

hep-th↗

arXiv2025

Uncertainty Principles and Non-local Black Holes

We discuss the Generalized Uncertainty Principle and the Extended Uncertainty Principle in the context of black hole solutions coming from non-local theories of gravity, focusing, specifically, on Infinite Derivative Gravity. We argue that these modifications of the Heisenberg Uncertainty Principle are effective descriptions arising from the non-local features of gravitational interaction. By comparing the predictions of both the modified uncertainty principles and non-local gravity, we find theoretical constraints on otherwise free parameters as well as universal laws for black hole physics beyond General Relativity.

gr-qc↗

arXiv2025

Pre-geometric Einstein-Cartan Field Equations and Emergent Cosmology

The field equations of pre-geometric theories of gravity are derived and analysed, both without and with matter. After the spontaneous symmetry breaking that reduces the gauge symmetry of these theories à la Yang-Mills, a metric structure for spacetime emerges and the field equations recover both the Einstein and the Cartan field equations for gravity. A first exact solution of the pre-geometric field equations is also presented. This solution can be considered as a pre-geometric de Sitter universe and provides a possible resolution for the problem of the Big Bang singularity.

gr-qc↗

arXiv2025

Hamiltonian Analysis of Pre-geometric Gravity

The Einstein-Cartan theory of gravity can arise from a mechanism of spontaneous symmetry breaking within the context of pre-geometric gauge theories. In this work, we develop the Hamiltonian analysis of such theories. By making contact with the ADM formalism, we show that all the results of canonical General Relativity are correctly recovered in the IR limit of the spontaneously broken phase. We then apply Dirac's algorithm to study the algebra of constraints and determine the number of degrees of freedom in the UV limit of the unbroken phase. We also discuss possible pathways toward a UV completion of General Relativity, including a pre-geometric generalisation of the Wheeler-DeWitt equation and an extended BF formulation of the pre-geometric theory.

gr-qc↗

arXiv2025

The Weinberg no-go theorem for cosmological constant and nonlocal gravity

We show how a nonlocal gravitational interaction can circumvent the Weinberg no-go theorem on cosmological constant, which forbids the existence of any solution to the cosmological constant problem within the context of local field theories unless some fine-tuning is assumed. In particular, Infinite Derivative Gravity theories hint at a possible understanding of the cosmological constant as a nonlocal gravitational effect on very large scales. In this perspective, one can describe the observed cosmic acceleration in terms of an effective field theory without relying on the fine-tuning of parameters or additional matter fields.

gr-qc↗

arXiv2025

Gravity from Pre-geometry

The gravitational interaction, as described by the Einstein-Cartan theory, is shown to emerge as the by-product of the spontaneous symmetry breaking of a gauge symmetry in a pre-geometric four-dimensional spacetime. Starting from a formulation à la Yang-Mills on an SO(1,4) or SO(3,2) principal bundle and not accounting for a spacetime metric, the Einstein-Hilbert action is recovered after the identification of the effective spacetime metric and spin connection for the residual SO(1,3) gauge symmetry of the spontaneously broken phase - i.e. the stabiliser of the SO(1,4) or SO(3,2) gauge group. Thus, the two fundamental tenets of General Relativity, i.e. diffeomorphism invariance and the equivalence principle, can arise from a more fundamental gauge principle. The two mass parameters that characterise Einstein gravity, namely the Planck mass and the cosmological constant, are likewise shown to be emergent, with the correct sign for the cosmological constant depending on whether the fundamental gauge group is taken to be either the de Sitter or the anti-de Sitter group. The phase transition from the unbroken to the spontaneously broken phase is expected to happen close to the Planck temperature. This is conjectured to be dynamically driven by a scalar field that implements a Higgs mechanism, hence providing mass to new particles, with consequences for cosmology and high-energy physics. The couplings of gravity to matter are discussed after drawing up a dictionary that interconnects pre-geometric and effective geometric quantities. In the unbroken phase where the fundamental gauge symmetry is restored, the theory is potentially power-counting renormalisable without matter, offering a novel path towards a UV completion of Einstein gravity.

hep-th↗

arXiv2024

Can nonlocal gravity really explain dark energy?

In view to scrutinize the idea that nonlocal modifications of General Relativity could dynamically address the dark energy problem, we investigate the evolution of the Universe at infrared scales as an Infinite Derivative Gravity model of the Ricci scalar, without introducing the cosmological constant $Λ$ or any scalar field. The accelerated expansion of the late Universe is shown to be compatible with the emergence of nonlocal gravitational effects at sufficiently low energies. A technique for circumventing the mathematical complexity of the nonlocal cosmological equations is developed and, after drawing a connection with the Starobinsky gravity, verifiable predictions are considered, like a possible decreasing in the strength of the effective gravitational constant. In conclusion, the emergence of nonlocal gravity corrections at given scales could be an efficient mechanism to address the dark energy problem.

gr-qc↗