ﻻ يوجد ملخص باللغة العربية
In this work we have studied the nonlinear preheating dynamics of the $frac{1}{4} lambda phi^4$ inflationary model. It is well established that after a linear stage of preheating characterized by the parametric resonance, the nonlinear dynamics becomes relevant driving the system towards turbulence. Wave turbulence is the appropriated description of this phase since matter distributions are fields instead of usual fluids. Therefore, turbulence develops due to the nonlinear interations of waves, here represented by the small inhomogeneities of the inflaton field. We present relevant aspects of wave turbulence such as the Kolmogorov-Zakharov spectrum in frequency and wave number domains that indicates that there are a transfer of energy through scales. From the power spectrum of the matter energy density we were able to estimate the temperature of the thermalized system.
Cubic Galileon massive gravity is a development of de Rham-Gabadadze-Tolly (dRGT) massive gravity theory is which the space of the Stueckelberg field is broken. We consider the cubic Galileon term as a scalar field coupled to the graviton filed. We p
In Eddington gravity, the action principle involves only the symmetric parts of the connection and the Ricci tensor, with a metric that emerges proportionally to the latter. Here, we relax this symmetric character, prolong the action with the antisym
This Thesis is devoted to the study of Metric-Affine Theories of Gravity and Applications to Cosmology. The thesis is organized as follows. In the first Chapter we define the various geometrical quantities that characterize a non-Riemannian geometry.
The Palatini gravitational action is enlarged by an arbitrary function $f(X)$ of the determinants of the Ricci tensor and the metric, $X=|textbf{det}.R|/|textbf{det}.g|$. The resulting Ricci-determinant theory exhibits novel deviations from general r
In this work we consider black holes surrounded by anisotropic fluids in four dimensions. We first study the causal structure of these solutions showing some similarities and differences with Reissner-Nordstrom-de Sitter black holes. In addition, we