Gauss–Bonnet modified gravity models with bouncing behavior

Bouncing cosmologies in Palatini fðRÞ gravity

Hèlios Sanchis-Alepuz Departamento de Fı́sica Teórica and IFIC, Centro Mixto Universidad de Valencia-CSIC. Facultad de Fı́sica, Universidad de Valencia, Burjassot-46100, Valencia, Spain and Fachbereich Theoretische Physik, Institut für Physik, Karl-Franzens-Universität Graz, Universitätsplatz 5, A-8010 Graz, Austria (Received 12 June 2009; published 16 July 2009) We consider the early time cosmol...

Bouncing Universes in String-inspired Gravity

We consider the effects on cosmology of higher-derivative modifications of (effective) gravity that make it asymptotically free without introducing ghosts. The weakening of gravity at short distances allows pressure to prevent the singularity, producing a solution with contraction preceding expansion.

Equivalence Principle Implications of Modified Gravity Models

Generalized modified gravity models: the stability issue

A brief introduction on the issue of stability in generalized modified gravity is presented and the dynamical system methods are used in the investigation of the stability of spatially flat homogeneous cosmologies within a large class of generalized modified gravity models in the presence of a relativistic matter-radiation fluid.

Exact Solutions in Modified Gravity Models

We review the exact solutions in modified gravity. It is one of the main problems of mathematical physics for the gravity theory. One can obtain an exact solution if the field equations reduce to a system of ordinary differential equations. In this paper we consider a number of exact solutions obtained by the method of separation of variables. Some applications to Cosmology and BH entropy are b...