2014/08/31 by Eduardo Guendelman, Ramón Herrera, Pedro Labraña +2 · 3 citations
Physics and Astronomy · #gr-qc #hep-th
paper · pdf · doi:10.1007/s10714-015-1852-1
published as General Relativity and Gravitation 47 (2015) art.10 · v.1 14 pages, 2 figures; v.2 references and acknowledgements added; v.3 very significant upgrade - 24 pages, change of list of authors, two new sections, extended abstract, introduction and conclusions, additional citations and acknowledgements; v.4 title shortened, further improvements, version to appear in "General Relativity and Gravitation"
arxiv created 2015/01/08 · arxiv updated 2015/06/22
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 non-singular "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.