161 citations · 685 across the 15 of their papers we have counts for
15 papers
Supersymmetric k-defects
Michael Koehn, Mark Trodden
In supersymmetric theories, topological defects can have nontrivial behaviors determined purely by whether or not supersymmetry is restored in the defect core. A well-known example…
Non-Singular Bouncing Cosmology: Consistency of the Effective Description
Michael Koehn, Jean-Luc Lehners, Burt Ovrut
We explicitly confirm that spatially flat non-singular bouncing cosmologies make sense as effective theories. The presence of a non-singular bounce in a spatially flat universe imp…
Towards a Solution of the Negative Mode Problem in Quantum Tunnelling with Gravity
Michael Koehn, George Lavrelashvili, Jean-Luc Lehners
In the absence of gravity, one can prove that tunnelling instantons exhibit exactly one negative mode in their spectrum of fluctuations. It is precisely the existence of this tunne…
Cosmological Perturbations Through a Non-Singular Ghost-Condensate/Galileon Bounce
Lorenzo Battarra, Michael Koehn, Jean-Luc Lehners +1
We study the propagation of super-horizon cosmological perturbations in a non-singular bounce spacetime. The model we consider combines a ghost condensate with a Galileon term in o…
A Cosmological Super-Bounce
Michael Koehn, Jean-Luc Lehners, Burt A. Ovrut
We study a model for a non-singular cosmic bounce in N=1 supergravity, based on supergravity versions of the ghost condensate and cubic Galileon scalar field theories. The bounce i…
What the characters of irreducible subrepresentations of Jordan cells can tell us about LCFT
Michael Flohr, Michael Koehn
In this article, we review some aspects of logarithmic conformal field theories which can be inferred from the characters of irreducible submodules of indecomposable modules. We wi…