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R. A. C. Correa

Publications and source records attributed to R. A. C. Correa.

At least 37 records · Page 2Linked to original sources
arXiv2016

Analytical general solutions for static wormholes in $f(R,T)$ gravity

Originally proposed as a tool for teaching the general theory of relativity, wormholes are today approached in many different ways and are seeing as an efficient alternative for interstellar and time travel. Attempts to achieve observational signatures of wormholes have been growing as the subject has became more and more popular. In this article we investigate some $f(R,T)$ theoretical predictions for static wormholes, i.e., wormholes whose throat radius can be considered a constant. Since the $T$-dependence in $f(R,T)$ gravity is due to the consideration of quantum effects, a further investigation of wormholes in such a theory is well motivated. We obtain the energy conditions of static wormholes in $f(R,T)$ gravity and apply an analytical approach to find the solutions. We highlight that our results are in agreement with previous solutions presented in the literature.

gr-qc↗
arXiv2016

Refinements of the Weyl pure geometrical thick branes from information-entropic measure

This letter aims to analyse the so-called configurational entropy in the Weyl pure geometrical thick brane model. The Weyl structure plays a prominent role in the thickness of this model. We find a set of parameters associated to the brane width where the configurational entropy exhibits critical points. Furthermore, we show, by means of this information-theoretical measure, that a stricter bound on the parameter of Weyl pure geometrical brane model arises from the CE.

hep-th↗
arXiv2016

Evading the non-continuity equation in the f(R, T) formalism

We present a new approach for the $f(R,T)$ formalism, by exploring the extra terms of its effective energy-momentum tensor $T_{μν}^{eff}$, namely $\tilde{T}_{μν}$. Those arise from the consideration of quantum effects, which are usually neglected in general relativity and $f(R)$ theories, and are summed to the usual matter energy-momentum tensor, yielding $T_{μν}^{eff}=T_{μν}+\tilde{T}_{μν}$. Purely from the Bianchi identities, the conservation of both parts of the effective energy-momentum tensor is obtained, rather than the non-conservation of the matter one, originally approached in the $f(R,T)$ theories. In this way, the intriguing scenario of matter-creation, which still lacks observational evidences, is evaded. One is left, then, with two sets of cosmological equations to be solved: the Friedmann-like equations along with the conservation of $T_{μν}$ and along with the conservation of $\tilde{T}_{μν}$. We present a physical interpretation for the conservation of the extra terms of the effective energy-momentum tensor, which is related to the presence of stiff matter in the universe. The cosmological features of this approach are presented and discussed as well as the benefits of evading the matter energy-momentum tensor non-conservation.

gr-qc↗
arXiv2016

Configurational entropy as a bounding of Gauss-Bonnet braneworld models

Configurational entropy has been revealed as a reliable method for constraining some parameters of a given model [Phys. Rev. D \textbf{92} (2015) 126005, Eur. Phys. J. C \textbf{76} (2016) 100]. In this letter we calculate the configurational entropy in Gauss-Bonnet braneworld models. Our results restrict the range of acceptability of the Gauss-Bonnet scalar values. In this way, the information theoretical measure in Gauss-Bonnet scenarios opens a new window to probe situations where the additional parameters, responsible for the Gauss-Bonnet sector, are arbitrary. We also show that such an approach is very important in applications that include p and Dp-branes and various superstring-motivated theories.

hep-th↗
arXiv2016

A transition from a decelerated to an accelerated phase of the universe expansion from the simplest non-trivial polynomial function of T in the f(R,T) formalism

In this work we present cosmological solutions from the simplest non-trivial $T$-dependence in $f(R,T)$ theory of gravity, with $R$ and $T$ standing for the Ricci scalar and trace of the energy-momentum tensor, respectively. Although such an approach yields a highly non-linear differential equation for the scale factor, we show that it is possible to obtain analytical solutions for the cosmological parameters. For some values of the free parameters, the model is able to predict a transition from a decelerated to an accelerated expansion of the universe.

hep-th↗
arXiv2016

Bounds on topological Abelian string-vortex and string-cigar from information-entropic measure

In this work we obtain bounds on the topological Abelian string-vortex and on the string-cigar, by using a new measure of configurational complexity, known as configurational entropy. In this way, the information-theoretical measure of six-dimensional braneworlds scenarios are capable to probe situations where the parameters responsible for the brane thickness are arbitrary. The so-called configurational entropy (CE) selects the best value of the parameter in the model. This is accomplished by minimizing the CE, namely, by selecting the most appropriate parameters in the model that correspond to the most organized system, based upon the Shannon information theory. This information-theoretical measure of complexity provides a complementary perspective to situations where strictly energy-based arguments are inconclusive. We show that the higher the energy the higher the CE, what shows an important correlation between the energy of the a localized field configuration and its associated entropic measure.

hep-th↗
arXiv2016

On the study of oscillons in scalar field theories: A new approach

In this work we study configurations in one-dimensional scalar field theory, which are time-dependent, localized in space and extremely long-lived called oscillons. It is investigated how the action of changing the minimum value of the field configuration representing the oscillon affects its behavior. We find that one of the consequences of this procedure, is the appearance of a pair of oscillon-like structures presenting different amplitudes and frequencies of oscillation. We also compare our analytical results to numerical ones, showing excellent agreement.

hep-th↗
arXiv2016

Braneworld cosmology in $f(R,T)$ gravity

Braneworld scenarios consider our observable universe as a brane embedded in a 5D space, named bulk. In this work, I derive the field equations of a braneworld model in a generalized theory of gravitation, namely $f(R,T)$ gravity, with $R$ and $T$, representing the Ricci scalar and the trace of the energy-momentum tensor, respectively. The cosmological parameters obtained from this approach are in agreement with recent constraints from Supernovae Ia data combined with baryon acoustic oscillations and cosmic microwave background observations, favouring such an alternative description of the universe dynamics.

gr-qc↗
arXiv2015

On the Hamilton-Jacobi method in classical and quantum nonconservative systems

In this work we show how to complete some Hamilton-Jacobi solutions of linear, nonconservative classical oscillatory systems which appeared in the literature and we extend these complete solutions to the quantum mechanical case. In addition, we get the solution of the quantum Hamilton-Jacobi equation for an electric charge in an oscillating pulsing magnetic field. We also argue that for the case where a charged particle is under the action of an oscillating magnetic field, one can apply nuclear magnetic resonance techniques in order to find experimental results regarding this problem. We obtain all results analytically, showing that the quantum Hamilton-Jacobi formalism is a powerful tool to describe quantum mechanics.

quant-ph↗
arXiv2015

Configurational entropy in $f(R,T)$ brane models

In this work we investigate generalized theories of gravity in the so-called configurational entropy (CE) context. We show, by means of this information-theoretical measure, that a stricter bound on the parameter of $f(R,T)$ brane models arises from the CE. We find that these bounds are characterized by a valley region in the CE profile, where the entropy is minimal. We argue that the CE measure can open a new role and an important additional approach to select parameters in modified theories of gravitation.

hep-th↗
arXiv2015

Information content in $F(R)$ brane models with non-constant curvature

In this work we investigate the entropic information-measure in the context of braneworlds with non-constant curvature. The braneworld entropic information is studied for gravity modified by the squared of the Ricci scalar, besides the usual Einstein-Hilbert term. We showed that the minimum value of the brane configurational entropy provides a stricter bound on the parameter that is responsible for the $F(R)$ model to differ from the Einstein-Hilbert standard one. Our results are moreover consistent to a negative bulk cosmological constant.

hep-th↗
arXiv2015

False Vacuum Transitions - Analytical Solutions and Decay Rate Values

In this work we show a class of oscillating configurations for the evolution of the domain walls in Euclidean space. The solutions are obtained analytically. Phase transitions are achieved from the associated fluctuation determinant, by the decay rates of the false vacuum.

hep-th↗
arXiv2015

D-Oscillons in the Standard Model-Extension

In this work we investigate the consequences of the Lorentz symmetry violation on extremely long-living, time-dependent, and spatially localized field configurations, named oscillons. This is accomplished in ($D+1$) dimensions for two interacting scalar field theories in the so-called Standard Model-Extension context. We show that $D$-dimensional scalar field lumps can present a typical size $R_{\min }\ll R_{KK}$, where $R_{KK}$ is the associated length scale of extra dimensions in Kaluza-Klein theories. Here, the size $R_{\min }$ is shown to strongly depend on the terms that control the Lorentz violation of the theory. This implies either contraction or dilation of the average radius $R_{\min}$, and a new rule for its composition, likewise. Moreover, we show that the spatial dimensions for existence of oscillating lumps have an upper limit, opening new possibilities to probe the existence of a $D$ -dimensional oscillons at TeV energy scale. Moreover, in a cosmological scenario with Lorentz symmetry breaking, we argue that in the early Universe with an extremely high energy density and a strong Lorentz violation, the typical size $R_{\min }$ was highly dilated. With the expansion and subsequent cooling of the Universe, we propose that it passed through a phase transition towards a Lorentz symmetry, wherein $R_{\min }$ tends to be compact.

hep-th↗
arXiv2015

Coupled scalar fields Oscillons and Breathers in some Lorentz Violating Scenarios

In this work we discuss the impact of the breaking of the Lorentz symmetry on the usual oscillons, the so-called flat-top oscillons, and the breathers. Our analysis is performed by using a Lorentz violation scenario rigorously derived in the literature. We show that the Lorentz violation is responsible for the origin of a kind of deformation of the configuration, where the field configuration becomes oscillatory in a localized region near its maximum value. Furthermore, we show that the Lorentz breaking symmetry produces a displacement of the oscillon along the spatial direction, the same feature is present in the case of breathers. We also show that the effect of a Lorentz violation in the flat-top oscillon solution is responsible by the shrinking of the flat-top. Furthermore, we find analytically the outgoing radiation, this result indicates that the amplitude of the outgoing radiation is controlled by the Lorentz breaking parameter, in such away that this oscillon becomes more unstable than its symmetric counterpart, however, it still has a long living nature.

hep-th↗
arXiv2015

Configurational Entropy in Brane-world Models: A New Approach to Stability

In this work we investigate the entropic information on thick brane-worlds scenarios and its consequences. The brane-world entropic information is studied for the sine-Gordon model is and hence the brane-world entropic information measure is shown an accurate way for providing the most suitable values for the bulk AdS curvature. Besides, the brane-world configurational entropy is employed to demonstrate a high organisational degree in the structure of the system configuration, for large values of a parameter of the sine-Gordon model but the one related to the AdS curvature. The Gleiser and Stamatopoulos procedure is finally applied in order to achieve a precise correlation between the energy of the system and the brane-world configurational entropy.

hep-th↗
arXiv2015

Information-Entropic for Travelling Solitons in Lorentz and CPT Breaking Systems

In this work we group three research topics apparently disconnected, namely solitons, Lorentz symmetry breaking and entropy. Following a recent work [Phys. Lett. B 713 (2012) 304], we show that it is possible to construct in the context of travelling wave solutions a configurational entropy measure in functional space, from the field configurations. Thus, we investigate the existence and properties of travelling solitons in Lorentz and CPT breaking scenarios for a class of models with two interacting scalar fields. Here, we obtain a complete set of exact solutions for the model studied which display both double and single-kink configurations. In fact, such models are very important in applications that include Bloch branes, Skyrmions, Yang-Mills, Q-balls, oscillons and various superstring-motivated theories. We find that the so-called Configurational Entropy (CE) for travelling solitons, which we name as travelling Configurational Entropy (TCE), shows that the best value of parameter responsible to break the Lorentz symmetry is one where the energy density is distributed equally around the origin. In this way, the information-theoretical measure of travelling solitons in Lorentz symmetry violation scenarios opens a new window to probe situations where the parameters responsible for breaking the symmetries are random. In this case, the TCE selects the best value.

hep-th↗
arXiv2014

Information-Entropic Measure of Energy-Degenerate Kinks in Two-Field Models

We investigate the existence and properties of kink-like solitons in a class of models with two interacting scalar fields. In particular, we focus on models that display both double and single-kink solutions, treatable analytically using the Bogomol'nyi--Prasad--Sommerfield bound (BPS). Such models are of interest in applications that include Skyrmions and various superstring-motivated theories. Exploring a region of parameter space where the energy for very different spatially-bound configurations is degenerate, we show that a newly-proposed momentum-space entropic measure called Configurational Entropy (CE) can distinguish between such energy-degenerate spatial profiles. This information-theoretic measure of spatial complexity provides a complementary perspective to situations where strictly energy-based arguments are inconclusive.

hep-th↗