55 citations · 119 across the 4 of their papers we have counts for
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Converting entropy to curvature perturbations after a cosmic bounce
Angelika Fertig, Jean-Luc Lehners, Enno Mallwitz +1
We study two-field bouncing cosmologies in which primordial perturbations are created in either an ekpyrotic or a matter-dominated contraction phase. We use a non-singular ghost co…
The Non-Minimal Ekpyrotic Trispectrum
Angelika Fertig, Jean-Luc Lehners
Employing the covariant formalism, we derive the evolution equations for two scalar fields with non-canonical field space metric up to third order in perturbation theory. These equ…
Conflation: a new type of accelerated expansion
Angelika Fertig, Jean-Luc Lehners, Enno Mallwitz
In the framework of scalar-tensor theories of gravity, we construct a new kind of cosmological model that conflates inflation and ekpyrosis. During a phase of conflation, the unive…
Ekpyrotic Perturbations With Small Non-Gaussian Corrections
Angelika Fertig, Jean-Luc Lehners, Enno Mallwitz
The entropic mechanism for producing nearly scale-invariant density perturbations in a contracting ekpyrotic universe relies on having an unstable scalar potential. Here we develop…