Dynamically generated inflationary twofield potential via nonRiemannian volume forms
Abstract
We consider a simple model of modified gravity interacting with a single scalar field φ with weakly coupled exponential potential within the framework of nonRiemannian spacetime volumeform formalism. The specific form of the action is fixed by the requirement of invariance under global Weylscale symmetry. Upon passing to the physical Einstein frame we show how the nonRiemannian volume elements create a second canonical scalar field u and dynamically generate a nontrivial twoscalarfield potential U_{eff} (u , φ) with two remarkable features: (i) it possesses a large flat region for large u describing a slowroll inflation; (ii) it has a stable lowlying minimum w.r.t. (u , φ) representing the dark energy density in the "late universe". We study the corresponding twofield slowroll inflation and show that the pertinent slowroll inflationary curve φ = φ (u) in the twofield space (u , φ) has a very small curvature, i.e., φ changes very little during the inflationary evolution of u on the flat region of U_{eff} (u , φ). Explicit expressions are found for the slowroll parameters which differ from those in the singlefield inflationary counterpart. Numerical solutions for the scalar spectral index and the tensortoscalar ratio are derived agreeing with the observational data.
 Publication:

Nuclear Physics B
 Pub Date:
 February 2020
 DOI:
 10.1016/j.nuclphysb.2019.114907
 arXiv:
 arXiv:1907.07625
 Bibcode:
 2020NuPhB.95114907B
 Keywords:

 Astrophysics  Cosmology and Nongalactic Astrophysics;
 General Relativity and Quantum Cosmology;
 High Energy Physics  Theory
 EPrint:
 13 pages. 2 Fig. arXiv admin note: text overlap with arXiv:1906.06691 , v.2 14 pages, typos corrected, additional explanations