Document Type

Article

Publication Date

7-9-2018

Publication Title

Physical Review D - Particles, Fields, Gravitation, and Cosmology

Department

Department of Physics and Astronomy

Abstract

We develop a non-singular bouncing cosmology using a non-trivial coupling of general relativity to fermionic fields. The usual Big Bang singularity is avoided thanks to a negative energy density contribution from the fermions. Our theory is ghost-free since the fermionic operator that generates the bounce is equivalent to torsion, which has no kinetic terms. The physical system consists of standard general relativity plus a topological sector for gravity, and fermionic matter described by Dirac fields with a non-minimal coupling. We show that a scale invariant power-spectrum generated in the contracting phase can be recovered by suitable choice s of fermion number density and bare mass, thus providing a possible alternative to the inflationary scenario.

DOI

10.1103/PhysRevD.90.123510

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