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Universe 2016, 2(1), 3;

String-Inspired Gravity through Symmetries

Departamento Física, Facultad Ciencias Naturales, Universidad de Atacama, Copayapu 485, Copiapó, Chile
Academic Editors: Lorenzo Iorio, Kazuharu Bamba and Sergei D. Odintsov
Received: 23 June 2015 / Revised: 27 January 2016 / Accepted: 27 January 2016 / Published: 5 February 2016
(This article belongs to the Special Issue Modified Gravity Cosmology: From Inflation to Dark Energy)
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We study a string-inspired cosmological model from the symmetries point of view. We start by deducing the form that each physical quantity must take so that the field equations, in the string frame, admit self-similar solutions. In the same way, we formalize the use of power-law solutions (less restrictive than the self-similar ones) by studying the wave equation for the dilaton through the Lie group method. Furthermore, we show how to generate more solutions by using this approach. As examples, we calculate exact solutions to several cosmological models in the four-dimensional NS-NS (Neveu-Schwarz-Neveu-Schwarz) sector of low-energy effective string theory coupled to a dilaton and an axion-like H-field within the string frame background, with FRW and the Bianchi Type II metrics. We also study the existence of Noether symmetries, which allow us to determine the form of the physical quantities in the framework of FRW geometry and to find exact cosmological solutions. View Full-Text
Keywords: string-inspired cosmology; symmetry methods; exact solutions; FRW and Bianchi II models string-inspired cosmology; symmetry methods; exact solutions; FRW and Bianchi II models

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This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. (CC BY 4.0).

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Belinchón, J.A. String-Inspired Gravity through Symmetries. Universe 2016, 2, 3.

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