Navegando por Autor "Pompeia, P. J."
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Artigo Cosmic acceleration from second order gauge gravity(Springer, 2010-09-21) Medeiros, Léo Gouvêa; Cuzinatto, R.R.; Melo, C.A.M. de; Pompeia, P. J.We construct a phenomenological theory of gravitation based on a second order gauge formulation for the Lorentz group. The model presents a long-range modification for the gravitational field leading to a cosmological model provided with an accelerated expansion at recent times. We estimate the model parameters using observational data and verify that our estimative for the age of the Universe is of the same magnitude than the one predicted by the standard model. The transition from the decelerated expansion regime to the accelerated one occurs recently (at ∼9.3 Gyr)Artigo How can one probe podolsky electrodynamics?(World Scientific Publishing, 2011-08-20) Medeiros, Léo Gouvêa; Cuzinatto, R.R.; Melo, C. A. M. de; Pompeia, P. J.We investigate the possibility of detecting the Podolsky generalized electrodynamics constant a. First we analyze an ion interferometry apparatus proposed by B. Neyenhuis et al. (Phys. Rev. Lett. 99, 200401 (2007)), who looked for deviations from Coulomb’s inverse-square law in the context of Proca model. Our results show that this experiment has not enough precision for measurements of a. In order to set up bounds for a, we investigate the influence of Podolsky’s electrostatic potential on the ground state of the Hydrogen atom. The value of the ground state energy of the Hydrogen atom requires Podolsky’s constant to be smaller than 5.6 fm, or in energy scales larger than 35.51 MeVArtigo Non-linear effects on radiation propagation around a charged compact object(Springer, 2015-09-23) Medeiros, Léo Gouvêa; Cuzinatto, R.R.; Melo, C. A. M. de; Vasconcelos, K. C. de; Pompeia, P. J.The propagation of non-linear electromagnetic waves is carefully analyzed on a curved spacetime created by static spherically symmetric mass and charge distribution. We compute how non-linear electrodynamics affects the geodesic deviation and the redshift of photons propagating near this massive charged object. In the first order approximation, the effects of electromagnetic self-interaction can be distinguished from the usual Reissner–Nordström terms. In the particular case of Euler–Heisenberg effective Lagrangian, we find that these self-interaction effects might be important near extremal compact charged objects