Electron-Electron Bound States in Maxwell-Chern-Simons-Proca QED3

We start from a parity-breaking MCS QED$_{3}$ model with spontaneous breaking of the gauge symmetry as a framework for evaluation of the electron-electron interaction potential and for attainment of numerical values for the e-e bound state. Three expressions are obtained for the potential according to the polarization state of the scattered electrons. In an energy scale compatible with Condensed Matter electronic excitations, these three potentials become degenerated. The resulting potential is implemented in the Schrodinger equation and the variational method is applied to carry out the electronic binding energy. The resulting binding energies in the scale of 10-100 meV and a correlation length in the scale of 10-30 Angs. are possible indications that the MCS-QED$_{3}$ model adopted may be suitable to address an eventual case of e-e pairing in the presence of parity-symmetry breakdown. The data analyzed here suggest an energy scale of 10-100 meV to fix the breaking of the U(1)-symmetry. PACS numbers: 11.10.Kk 11.15.Ex 74.20.-z 74.72.-h ICEN-PS-01/17Comment: 13 pages, style revtex, revised versio

Quantum Isotropization of the Universe

We consider minisuperspace models constituted of Bianchi I geometries with a free massless scalar field. The classical solutions are always singular (with the trivial exception of flat space-time), and always anisotropic once they begin anisotropic. When quantizing the system, we obtain the Wheeler-DeWitt equation as a four-dimensional massless Klein-Gordon equation. We show that there are plenty of quantum states whose corresponding bohmian trajectories may be non-singular and/or presenting large isotropic phases, even if they begin anisotropic, due to quantum gravitational effects. As a specific example, we exhibit field plots of bohmian trajectories for the case of gaussian superpositions of plane wave solutions of the Wheeler-DeWitt equation which have those properties. These conclusions are valid even in the absence of the scalar field.Comment: 10 pages, RevTeX, 3 Postscript figures, uses graficx.st

The unphysical character of dark energy fluids

It is well known that, in the context of general relativity, an unknown kind of matter that must violate the strong energy condition is required to explain the current accelerated phase of expansion of the Universe. This unknown component is called dark energy and is characterized by an equation of state parameter $w=p/\rho<-1/3$. Thermodynamic stability requires that $3w-d\ln |w|/d\ln a\ge0$ and positiveness of entropy that $w\ge-1$. In this paper we proof that we cannot obtain a differentiable function $w(a)$ to represent the dark energy that satisfies these conditions trough the entire history of the Universe.Comment: 8 pages, 1 figur

On Dirac-like Monopoles in a Lorentz- and CPT-violating Electrodynamics

We study magnetic monopoles in a Lorentz- and CPT-odd electrodynamical framework in (3+1) dimensions. This is the standard Maxwell model extended by means of a Chern-Simons-like term, $b_\mu\tilde{F}^{\mu\nu}A_\nu$ ($b_\mu$ constant), which respects gauge invariance but violates both Lorentz and CPT symmetries (as a consequence, duality is also lost). Our main interest concerns the analysis of the model in the presence of Dirac monopoles, so that the Bianchi identity no longer holds, which naively yields the non-conservation of electric charge. Since gauge symmetry is respected, the issue of charge conservation is more involved. Actually, the inconsistency may be circumvented, if we assume that the appearance of a monopole induces an extra electric current. The reduction of the model to (2+1) dimensions in the presence of both the magnetic sources and Lorentz-violating terms is presented. There, a quantization condition involving the scalar remnant of $b_\mu$, say, the mass parameter, is obtained. We also point out that the breaking of duality may be associated with an asymmetry between electric and magnetic sources in this background, so that the electromagnetic force experienced by a magnetic pole is supplemented by an extra term proportional to $b_\mu$, whenever compared to the one acting on an electric charge.Comment: 10 pages, no figures, typed in te