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Felipe de Melo Santos

Publications and source records attributed to Felipe de Melo Santos.

2 recordsLinked to original sources

Bohmian Quantization of a Nonminimal Coupling Cosmology

In a recent paper we studied the cosmology of Nonminimal Derivative Coupling (NDC) between gravity and a scalar field, which is a non-trivial class of Horndeski. We have shown that it presents a variety of solutions for the scale factor, but there are gravitational waves only for a very restrictive range in phase space, and primordial waves are completely forbidden classically in NDC. In this paper, we apply canonical quantization with the Bohm-de Broglie interpretation to that theory for a small value of the nonminimal coupling constant. We then study two quantum solutions of the Wheeler-DeWitt equation that lead to the perturbation of bouncing and cyclic solutions. By the analysis of the phase space obtained from the guidance equations of Bohm-de Broglie, we study the phase space determined by the scale factor and the scalar field for those quantum solutions in order to investigate three main aspects of that theory: the existence of non-singular solutions, the regions of accelerated expansion, and the regions compatible with the gravitational waves speed constraint. We conclude that there are non-singular solutions with an accelerated expansion period compatible with the constraint.

gr-qc↗

Nonminimal Derivative Coupling Cosmology and the Speed of Gravitational Waves

The so-called Nonminimal Derivative Coupling (NDC) is an alternative to General Relativity, which produces an asymptotic inflationary mechanism when applied to cosmology. The detection of gravitational waves in the last decade has imposed very stringent constraints over gravitational theories, which gave rise to a massive revision of those theories, in order to investigate the compatibility between them and that observational data. In this paper, we review NDC and address the question if it is compatible with gravitational waves or not. We show that the very existence of gravitational waves in this theory is restricted to a limited range in phase space and there are no accelerated solutions compatible with the present day data for the speed of such waves. This last result is alleviated by the fact that we did not detect primordial gravitational waves so far. Those conclusions are based on the comparison between the expression for the speed of tensor perturbations and the phase space. Finally, some possible scenarios and solutions are considered.

gr-qc↗