Emergent Cosmology, Inflation and Dark Energy from Gravity-Matter Model with Two Non-Riemannian Spacetime Volume Forms

Eduardo Guendelman, Ramón Herrera, Pedro Labrana, Emil Nissimov, Svetlana Pacheva

Research output: Contribution to journalArticle

Abstract

A new class of gravity-matter models defined in terms of two independent non-Riemannian volume forms (alternative generally covariant integration measure densities) on the space-time manifold are studied in some detail. These models involve an additional R2 (square of the scalar curvature) term as well as scalar matter field potentials of appropriate form so that the pertinent action is invariant under global Weyl-scale symmetry. Scale invariance is spontaneously
broken upon integration of the equations of motion for the auxiliary volume-form degrees of freedom. After performing transition to the physical Einstein frame we obtain: (i) An effective potential for the scalar field with two flat regions which allows for a unified description of both early universe inflation as well as of present dark energy epoch; (ii) For a definite parameter range the model possesses a nonsingular “emergent universe” solution which describes an initial phase of evolution that precedes the inflationary phase; (iii) For a reasonable choice of the parameters the present model conforms to the Planck Collaboration data.
Original languageEnglish
JournalarXiv preprint arXiv:1408.5344
StatePublished - 2014

Keywords

  • Modified gravity theories
  • Non-Riemannian volume forms
  • global Weyl-scale symmetry spontaneous breakdown
  • flat regions of scalar potential
  • Non-singular origin of the universe

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