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M. Novello

Publications and source records attributed to M. Novello.

At least 19 recordsLinked to original sources
arXiv2021

From weak interaction to gravity

We follow an old suggestion made by Stueckelberg that there exists an intimate connection between weak interaction and gravity, symbolized by the relationship between the Fermi and Newton\rq s constants. We analyze the hypothesis that the effect of matter upon the metric that represents gravitational interaction in General Relativity is an effective one. This leads us to consider gravitation to be the result of the interaction of two neutral spinorial fields (G-neutrinos) $ Ψ_{g}$ and $ Ω_{g}$ with all kinds of matter and energy. We present three examples with only one G-neutrino: two static and spherically symmetric configurations and a cosmological framework for an isotropic dynamical universe. Without self-interaction, the associated effective geometry is precisely the Schwarzschild metric. On the other hand, a self-interacting G-neutrino generates a new gravitational black-hole.

gr-qc↗
arXiv2020

A new gravitational black-hole

In a recent paper we have analyzed the Spinor Theory of Gravity (STG) which is based on the intimate relation between Fermi (weak) interaction and gravity. We presented the hypothesis that the effect of matter upon the metric that represents gravitational interaction in General Relativity is an effective one. This lead us to consider gravitation to be the result of the interaction of two neutral spinorial fields (G-neutrinos) $Ψ_g$ and $Ω_g$ with all kinds of matter and energy through the generation of such effective metric. In other words, the universal metric that represents gravitational interaction in the framework of General Relativity is constructed with the weak currents associated to $Ψ_g$ and $Ω_g$. In the first paper we have shown that when only one spinor exists, the effective metric of a static and spherically symmetric configuration is identical to the Schwarzschild geometry of GR. In the present paper we go one step further and consider the case in which the field $Ψ_g$ has a self-interaction. The solution of a static and spherically symmetric configuration is distinct from the previous one. This new solution presents another horizon that we compare with the case of Schwarzschild.

gr-qc↗
arXiv2019

The cosmological constant and a scalar field coupled non minimally to gravity

We show that the combined minimal and non minimal interaction with the gravitational field may produce the generation of a cosmological constant without self-interaction of the scalar field. In the same vein we analyze the existence of states of a scalar field that by a combined interaction of minimal and non minimal coupling with the gravitational field can exhibit an unexpected property, to wit, they are acted on by the gravitational field but do not generate gravitational field. In other words, states that seems to violate the action-reaction principle. We present explicit examples of this situation in the framework of a spatially isotropic and homogeneous universe.

gr-qc↗
arXiv2019

Gravitational waves in geometric scalar gravity

We investigate the gravitational waves phenomena in the geometric scalar theory of gravity (GSG) that belongs to a class of theories such that gravity is described by a single scalar field. The associated physical metric describing the spacetime is constructed from a disformal transformation of Minkowski geometry. In this theory, a weak field approximation gives rise to a description similar to that one obtained in general relativity, although the gravitational waves in GSG have a characteristic longitudinal polarization mode, besides others modes that are observer dependent. We also analyze the energy carried by the gravitational waves as well as how their emission affects the orbital period of a binary system.

gr-qc↗
arXiv2019

A new bifurcation in the Universe

We show that the combined system of general relativity with a non minimally coupled electromagnetic field presents a bifurcation in a cosmical framework driven by a cosmological constant. In the same framework we show the existence of states such that the resulting combined energy (the sum of the minimally and the non minimally coupled energy momentum tensor of the electromagnetic field) vanishes in a sort of violation of the action-reaction principle.

gr-qc↗
arXiv2017

Repulsive gravity induced by a conformally coupled scalar field implies a bouncing radiation-dominated universe

In the present work we revisit a model consisting of a scalar field with a quartic self-interaction potential non-minimally (conformally) coupled to gravity [1]. When the scalar field vacuum is in a broken symmetry state, an effective gravitational constant emerges which, in certain regimes, can lead to gravitational repulsive effects when only ordinary radiation is coupled to gravity. In this case, a bouncing universe is shown to be the only cosmological solution admissible by the field equations when the scalar field is in such a broken symmetry state.

gr-qc↗
arXiv2016

Gravitational mechanism for baryogenesis in the cosmological QCD phase transition

One of the biggest puzzles in modern cosmology is the observed baryon asymmetry in the universe. In current models of baryogenesis gravity plays a secondary role, although the process is believed to have happened in the early universe, under the influence of an intense gravitational field. In the present work we resume Sakharov's original program for baryogenesis and propose a central role for gravity in the process. This is achieved through a non-minimal coupling (NMC) between the gravitational field and both the strong interaction field and the quark fields. When in action, the present mechanism leads to baryon number non-conservation and CP violation. Moreover, the NMC induces reduced effective quark masses, which favours a first order QCD phase transition. As a consequence, a baryon asymmetry can be attained in the transition from the quark epoch to the hadron epoch.

gr-qc↗
arXiv2016

A possible interaction between uncharged particles and the Electromagnetic field

Maxwell Electrodynamics can be described either in Minkowski space-time or in a dynamically equivalent way in a curved geometry constructed in terms of the electromagnetic field. For this the field must have a superior bound limited by a maximum value of its energy. After showing such geometric equivalence we investigate the possibility that new processes dependent on the metric structure may appear. In particular for very high values of the field a direct coupling of uncharged particles to the electromagnetic field is predicted.

gr-qc↗
arXiv2016

The cosmological origins of nonlinear Electrodynamics

We present a mechanism that allows to describe any nonlinear theory of Electrodynamics as a consequence of the coupling of the electromagnetic field to gravity in the presence of a vacuum represented by the cosmological constant. We emphasize gravity\rq s exclusive role of catalysis.

gr-qc↗
arXiv2016

Cosmology of a Heisenberg fluid

We consider a scenario in which the global geometry of the universe is driven by non-linear fermions obeying Heisenberg dynamics.

gr-qc↗
arXiv2016

More about scalar gravity

We discuss a class of models for gravity based on a scalar field. The models include and generalize the old approach by Nordström which predated and in some way inspired General Relativity. The class include also a model that we have recently introduced and discussed in its cosmological aspects (GSG). We present here a complete characterisation of the Schwarschild geometry as a vacuum solution of GSG and sketch a discussion of the first Post-Newtonian approximation.

gr-qc↗
arXiv2014

Cosmology in GSG

We describe what cosmology looks like in the context of the geometric theory of gravity (GSG) based on a single scalar field. There are two distinct classes of cosmological solutions. An interesting feature is the possibility of having a bounce without invoking exotic equations of state for the cosmic fluid. We also discuss cosmological perturbation and present the basis of structure formation by gravitational instability in the framework of the geometric scalar gravity.

gr-qc↗
arXiv2014

Analogue black holes for light rays in static dielectrics

Propagation of light in nonlinear materials is here studied in the regime of the geometrical optics. It is shown that a spherically symmetric medium at rest with some specific dielectric properties can be used to produce an exact analogue model for a class of space-times which includes spherically symmetric and static black hole solutions. The optical model here presented can be a useful tool to reproduce in laboratory the behavior of optical null geodesics near a compact object with an observable gravitational Schwarzschild radius.

gr-qc↗
arXiv2013

The gravitational energy

We present the expression $t_{μν}$ of the energy-momentum tensor of the gravitational field in the framework of the recent proposal of the Geometric Scalar theory of gravity (GSG). From the conservation of $t_{μν}$ it follows the dynamics of the gravitational field. As an example of this expression for $t_{μν}$ we calculate the gravitational energy of a compact object.

gr-qc↗
arXiv2013

A proposal for the origin of the anomalous magnetic moment

We investigate a new form of contribution for the anomalous magnetic moment of all particles. This common origin is displayed in the framework of a recent treatment of electrodynamics that is based in the introduction of an electromagnetic metric which has no gravitational character. This effective metric constitutes a universal pure electromagnetic process perceived by all bodies, charged or not charged. As a consequence it yields a complementary explanation for the existence of anomalous magnetic moment for charged particles and even for non-charged particles like neutrino.

physics.gen-ph↗
arXiv2013

The Quasi-Maxwellian Equations of General Relativity: Applications to the Perturbation Theory

A comprehensive review of the equations of general relativity in the quasi-Maxwellian (QM) formalism introduced by Jordan, Ehlers and Kundt is made. Our main interest concerns its applications to the analysis of the perturbation of standard cosmology in the Friedman-Lemaître-Robertson-Walker framework. The major achievement of the QM scheme is its use of completely gauge independent quantities. We shall see that in the QM-scheme we deal directly with observable quantities. This reveals its advantage over the old method introduced by Lifshitz et al that deals with perturbation in the standard Einstein framework. For completeness, we compare the QM-scheme to the gauge-independent method of Bardeen, a procedure consisting on particular choices of the perturbed variables as a combination of gauge dependent quantities.

gr-qc↗