Publications (17)37.81 Total impact
 [Show abstract] [Hide abstract]
ABSTRACT: In this paper we use the conformal teleparallel gravity to study an isotropic and homogeneous Universe which is settled by the FRW metric. We solve the field equations and we obtain the behavior of some cosmological parameters such as scale factor, deceleration parameter and the energy density of the perfect fluid which is the matter field of our model. The field equations, that we called modified Friedmann equations, allow us to define a dark fluid, with dark energy density and dark pressure, responsible for the acceleration in the Universe.  [Show abstract] [Hide abstract]
ABSTRACT: In this paper, we will study noncommutative corrections in the metric tensor for the G\"{o}deltype universe, a model that has as its main characteristic the possibility of violation of causality, allowing therefore time travel. We also find that the critical radius in such a model, which eventually will determine the time travel possibility, is modified due to the non commutativity of spatial coordinates.  [Show abstract] [Hide abstract]
ABSTRACT: Here, we consider a gravity theory involving a spontaneous Lorentz symmetry breaking called the bumblebee model. We show that, at certain values of the bumblebee field, the G\"odel metric is consistent within this theory.  [Show abstract] [Hide abstract]
ABSTRACT: Rastall's theory is a generalization of Einstein's equations in which the energymomentum tensor is not a conserved quantity, its covariant derivative is proportional to the gradient of the Ricci scalar and this fact can be associated with quantum effects in curved spacetime. In this work we will go study the Rastall's gravity in the context of the G\"odeltype universe. 
Article: On Noncommutative Geodesic Motion
[Show abstract] [Hide abstract]
ABSTRACT: In this work we study the geodesic motion on a noncommutative spacetime. As a result we find a noncommutative geodesic equation and then we derive corrections of the deviation angle per revolution in terms of the noncommutative parameter when we specify the problem of Mercury's perihelion. In this way, we estimate the noncommutative parameter based in experimental data.  [Show abstract] [Hide abstract]
ABSTRACT: In this work, we have considered the Ricci dark energy model, where the energy density of the universe is proportional to the Ricci scalar curvature, in the dynamic ChernSimons modified gravity. We show that in this context the evolution of the scale factor is similar to that displayed by the modified Chaplygin gas.  [Show abstract] [Hide abstract]
ABSTRACT: In this paper, we work in the context of Teleparallelism Equivalent to General Relativity (TEGR) in order to construct the energy–momentum flux for Gödeltype solutions of Einstein's equations. We use an stationary observer, which is settled by the tetrad choice, to obtain the gravitational pressure for each direction of space in cartesian coordinates. Then, we write down the total pressure for each direction in terms of the pressure of the fluid, thus we are able to identify the role of the gravitational pressure.  [Show abstract] [Hide abstract]
ABSTRACT: We discuss the consistency of the Godel metric within the ChernSimons modified gravity, both for external and dynamical ChernSimons coefficients.  [Show abstract] [Hide abstract]
ABSTRACT: We formulate the nonminimal aethermodified gravity whose action represents itself as a sum of the usual EinsteinHilbert action and the CPTeven Lorentzbreaking aetherlike gravity term proposed by Carroll. For this theory, we show that the G\"{o}del metric solves the modified Einstein equations under a corresponding modification of the matter, while, for the small Lorentzbreaking corrections, the matter turns out to be usual (neither ghost nor phantom one). From the other side, if the matter is suggested to be the same as in the usual general relativity, the G\"{o}del metric must be modified by additive terms proportional to the Lorentzbreaking parameter to achieve its consistency with new equations of motion. Moreover, despite such a modification turns out to be nontrivial and cannot be completely removed via change of variables, nevertheless, the closed timelike curves (CTCs) can exist for a new metric. 
 [Show abstract] [Hide abstract]
ABSTRACT: We prove the consistency of the Gödel metric with the HoravaLifshitz gravity whose action involves terms with z=1, z=2, and z=3. We show that, for different relations between the parameters of the theory, this consistency is achieved for different classes of matter; in particular, for the small cosmological constant, it is achieved only for the exotic matterthat is, ghosts or phantom matter.  [Show abstract] [Hide abstract]
ABSTRACT: We study the conditions for the consistency of the FriedmannRobertsonWalker (FRW) metric with the dynamical ChernSimons modified gravity. It turns out to be that in this situation the accelerated expansion of the Universe takes place, with the time dependence of the scale factor turns out to be similar to the case of presence of the Chaplygin gas. Also we found that this modification changes the total density of the Universe and therefore gives a nontrivial impact to a cosmological scenario.  [Show abstract] [Hide abstract]
ABSTRACT: We study the condition for the consistency of the G\"{o}del metric with the dynamical ChernSimons modified gravity. It turns out to be that this compatibility can be achieved only if the cosmological constant is variable in the space.  [Show abstract] [Hide abstract]
ABSTRACT: In this paper we study the one and twoloop contribution to the free energy in QED with the Lorentz symmetry breaking introduced via constant CPTeven Lorentzbreaking parameters at the high temperature limit. We find the impact of the Lorentzviolating term for the free energy and carry out a numerical estimation for the Lorentzbreaking parameter. Comment: 8 pages, 3 figures, revtex4; v2: final version published in PRD 
Article: Gödel solution in modified gravity
[Show abstract] [Hide abstract]
ABSTRACT: The Silences of the Archives, the Reknown of the Story. The Martin Guerre affair has been told many times since Jean de Coras and Guillaume Lesueur published their stories in 1561. It is in many ways a perfect intrigue with uncanny resemblance, persuasive deception and a surprizing end when the two Martin stood face to face, memory to memory, before captivated judges and a guilty feeling Bertrande de Rols. The historian wanted to go beyond the known story in order to discover the world of the heroes. This research led to disappointments and surprizes as documents were discovered concerning the environment of Artigat’s inhabitants and bearing directly on the main characters thanks to notarial contracts. Along the way, study of the works of Coras and Lesueur took a new direction. Coming back to the affair a quarter century later did not result in finding new documents (some are perhaps still buried in Spanish archives), but by going back over her tracks, the historian could only be struck by the silences of the archives that refuse to reveal their secrets and, at the same time, by the possible openings they suggest, by the intuition that almost invisible threads link here and there characters and events.  [Show abstract] [Hide abstract]
ABSTRACT: In a 4D fourfermion model we study the dynamical restoration of Lorentz and CPT symmetries at finite temperature. We evaluate the gap equation both at zero and at finite temperature and observe that, depending on the parameters of the theory, there is a critical temperature at which the Lorentz and CPT symmetries are restored.  [Show abstract] [Hide abstract]
ABSTRACT: This paper has been withdrawn by the authors due to need of essential revision.
Publication Stats
68  Citations  
37.81  Total Impact Points  
Top Journals
Institutions

20112015

Universidade Federal de Mato Grosso (UFMT)
 Instituto de Física
Vila Real do Senhor Bom Jesus de Cuiabá, Mato Grosso, Brazil


2009

Universidade Federal da Paraíba
 Departamento de Física
João Pessoa, Estado da Paraiba, Brazil
