http://arxiv.org/abs/1402.5880
We develop a novel non-singular bouncing cosmology, due to the non-trivial coupling of general relativity to fermionic fields. The resolution of the singularity arises from the negative energy density provided by fermions. Our theory is ghost-free because the fermionic operator that generates the bounce is equivalent to torsion, which has no kinetic terms. The physical system is minimal in that it consists of standard general relativity plus a topological sector for gravity, a U$(1)$ gauge field reducing to radiation at late times 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 for a suitable choice of the fermion number density and the bare mass, hence providing a possible alternative to the inflationary scenario.
S. Alexander, C. Bambi, A. Marciano, et. al.
Tue, 25 Feb 14
14/59