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Stelios Stefas

Publications and source records attributed to Stelios Stefas.

12 recordsLinked to original sources
arXiv2026

Unification of Gravity with Internal Interactions: the SO(2,16) Scheme Revisited

The starting point of the present work is the observation that the tangent group of a curved manifold need not have the same dimension as the manifold itself. We use this fact to construct Conformal Gravity and its noncommutative (Fuzzy) counterpart as gauge theories, and then to unify both with internal gauge interactions. Specifically, we present a scheme in which conformal gravity, based on gauging the SO(2,4) group, and fuzzy gravity, based on gauging the SO(1,5)$\times$U(1), are unified with SO(10) internal interactions through the parent group SO(2,16), and we work through the resulting spontaneous symmetry breakings and fermion content in detail. We also discuss the low-energy phenomenology of the scheme, including cosmic-string gravitational-wave signals, and close with a brief outlook: a candidate minimal unification group, a dark-matter candidate suggested by the construction, and the ghost problem common to higher-derivative gravity theories of this type.

hep-th↗
arXiv2026

Conformal and Noncommutative Gravity from Gauge Symmetry Breaking and SO(2,16) Unification

Motivated by the old idea of treating gravity as a gauge theory, we review the gauge-theoretic construction of Conformal Gravity and of Noncommutative (Fuzzy) Gravity. We then outline how these gauge formulations of gravity can be unified with internal interactions described by an SO(10) Grand Unified Theory, based on the critical observation that the dimension of the tangent-space symmetry group of a curved manifold need not coincide with the spacetime dimension.

hep-th↗
arXiv2026

Unifying Gravities with Internal Interactions based on $SO(10)$ GUT

Building on two key ingredients, namely the well established gauge-theoretic formulation of gravity and the observation that the tangent space of a curved manifold need not have the same dimension as the manifold, we discuss how all known fundamental interactions can be accommodated within a single unified framework. The unification is realised by enlarging the tangent group of the four-dimensional spacetime manifold to $SO(2,16)$, a choice that simultaneously encompasses both the gauge group underlying the gravitational sector and the $SO(10)$ Grand Unified Theory for the internal interactions. The gravitational theories entering this construction are Conformal Gravity and Fuzzy (Noncommutative) Gravity, each formulated in gauge-theoretic terms.

hep-th↗
arXiv2025

Unifying Gravities with Internal Interactions

Reviving the old proposal of describing gravity as a gauge theory first we describe the construction of the Conformal and the Noncommutative (Fuzzy) Gravities in a gauge-theoretic manner. Then stressing the fact that the tangent group of a curved manifold and the manifold itself do not necessarily have the same dimensions, we show how the above Gravities can be unified with the Internal Interactions, the latter based on the GUT $SO(10)$.

hep-th↗
arXiv2025

Unification of Gravities with GUTs

Within the gauge-theoretic approach of gravity, the gauging of an enlarged symmetry of the tangent space in four dimensions allows gravity to be unified with internal interactions. We study the unification of the conformal and noncommutative (fuzzy) gravities with internal interactions based on the SO(10) GUT.

hep-th↗
arXiv2025

On the Unification of Conformal and Fuzzy Gravities with $SO(10)$ GUT

Within the gauge-theoretic approach of gravity, the gauging of an enlarged symmetry of the tangent space in four dimensions allows gravity to be unified with internal interactions. We study the unification of the Conformal and Noncommutative (Fuzzy) Gravities with Internal Interactions based on the $SO(10)$ GUT.

hep-th↗
arXiv2025

Unification of Conformal and Fuzzy Gravities with Internal Interactions - study of their behaviour in low energies and possible signals in the detection of Gravitational Waves

The Unification of Conformal and Fuzzy gravities with Internal Interactions is based on the following two facts. The first is that the tangent group of a curved manifold and the manifold itself do not necessarily have the same dimensions. The second is that both gravitational theories considered here have been formulated in a gauge theoretic way. Here we would like to start by reviewing the gauge theoretic approach of gravities commenting in particular their diffeomorphism invariance. Then we will review the construction of the Conformal Gravity and the Noncommutative (Fuzzy) Gravity using the gauge theoretic framework. Finally based on an extension of the four-dimensional tangent group we will present the Unification of both Gravities with the Internal Interactions. Both unified schemes will be examined further concerning their behaviour in low energies after suitable spontaneous symmetry breakings as well as the possible signals of the related cosmic strings in the gravitational waves.

gr-qc↗
arXiv2025

Unification of Conformal and Fuzzy Gravities with Internal Interactions resulting in SO(10) and a Possible Probe through Stochastic Gravitational Wave Background

The unification of conformal and fuzzy gravities with internal interactions is based on the facts that i) the tangent group of a curved manifold and the manifold itself do not necessarily have the same dimensions and ii) both gravitational theories considered here have been formulated in a gauge theoretic way. We review the gauge-theoretic approach of gravities, commenting in particular on their diffeomorphism invariance, and the construction of conformal and noncommutative (fuzzy) gravity using the gauge-theoretic framework. Based on an extension of the four-dimensional tangent group, unification of both gravities with the internal interactions is achieved. Both unified schemes are examined at 1-loop level considering suitable spontaneous symmetry breakings to a SO(10) grand unified theory and consequently down to the Standard Model of particle physics through four specific spontaneous breaking channels. Each channel is examined against proton lifetime experimental bounds and its observation potential through gravitational signal from cosmic strings production is discussed.

hep-th↗
arXiv2024

Fuzzy Gravity: Four-Dimensional Gravity on a Covariant Noncommutative Space and Unification with Internal Interactions

In the present work we present an extended description of the covariant noncommutative space, which accommodates the Fuzzy Gravity model constructed previously. It is based on the historical lesson that the use of larger algebras containing all generators of the isometry of the continuous one helped in formulating a fuzzy covariant noncommutative space. Specifically a further enlargement of the isometry group leads us, in addition to the construction of the covariant noncommutative space, also to the suggestion of the group that should be gauged on such a space in order to construct a Fuzzy Gravity theory. As a result, we obtain two Fuzzy Gravity models, one in de Sitter and one in anti-de Sitter space, depending on the extension of the isometry group, and we discuss their spontaneous symmetry breaking leading to fuzzy versions of the noncommutative $SO(1,3)$ gravity. In addition we discuss for the first time how to introduce fermions in the fuzzy gravity and even more importantly how to unify the constructed noncommutative-fuzzy gravity with internal interactions based on $SO(10)$ or $SU(5)$ as grand unified theories.

hep-th↗
arXiv2024

Unification of Conformal Gravity and Internal Interactions

Based on the observation that the dimension of the tangent space is not necessarily equal to the dimension of the corresponding curved manifold and on the known fact that gravitational theories can be formulated in a gauge theoretic way, we discuss how to describe all known interactions in a unified manner. This is achieved by enlarging the tangent group of the four-dimensional manifold to $SO(2,16)$, which permits the inclusion of both gauge groups, the one that describes gravity as a gauge theory as well as the $SO(10)$ describing the internal interactions. Moreover it permits the use of both Weyl and Majorana conditions imposed on the fermions, as to avoid the duplication of fermion multiplets of $SO(10)$ appearing in previous attempts. The gravity theory discussed in the present work is the Conformal Gravity which, after a spontaneous symmetry breaking, can lead either to Weyl Gravity or to the usual Einstein Gravity.

hep-th↗
arXiv2023

Intertwining noncommutativity with gravity and particle physics

Here we present an overview on the various works, in which many collaborators have contributed, regarding the interesting dipole of noncommutativity and physics. In brief, we present the features that noncommutativity triggers both in the fields of gravity and particle physics, from a matrix-realized perspective, with the notion of noncommutative gauge theories to play the most central role in the whole picture. Also, under the framework of noncommutativity, we examine the possibility of unifying the two fields (gravity-particle physics) in a single configuration.

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