Zobrazeno 1 - 10
of 71
pro vyhledávání: '"Koehn, Michael"'
Autor:
Koehn, Michael, Trodden, Mark
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 of this is that some supersymmetric cosmic strings are automatically
Externí odkaz:
http://arxiv.org/abs/1512.09138
Publikováno v:
Phys. Rev. D 93, 103501 (2016)
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 implies a temporary violation of the null energy condition, which can be
Externí odkaz:
http://arxiv.org/abs/1512.03807
Publikováno v:
Phys. Rev. D 92, 023506 (2015)
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 tunnelling negative mode that warrants an interpretation of these solutions
Externí odkaz:
http://arxiv.org/abs/1504.04334
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 order to induce a ghost-free bounce. Our calculation is performed in ha
Externí odkaz:
http://arxiv.org/abs/1404.5067
Publikováno v:
Phys. Rev. D 90, 025005 (2014)
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 is preceded by an ekpyrotic contracting phase which prevents the growth
Externí odkaz:
http://arxiv.org/abs/1310.7577
Autor:
Flohr, Michael, Koehn, Michael
Publikováno v:
J. Phys. A: Math. Theor. 46 (2013) 494007
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 will mainly consider the W(2,2p-1,2p-1,2p-1) series of triplet algebras
Externí odkaz:
http://arxiv.org/abs/1307.5844
Galileons are higher-derivative theories of a real scalar which nevertheless admit second order equations of motion. They have interesting applications as dark energy models and in early universe cosmology, and have been conjectured to arise as descr
Externí odkaz:
http://arxiv.org/abs/1302.0840
Autor:
Koehn, Michael
Publikováno v:
EPL 100 (2012) 60008
Employing a transformation to hyperbolic space, we derive in a simple way exact solutions for the Klein-Gordon equation in an infinite square-well potential with one boundary moving at constant velocity, for the massless as well as for the massive ca
Externí odkaz:
http://arxiv.org/abs/1301.0436
We present the theory of a supersymmetric ghost condensate coupled to N=1 supergravity. This is accomplished using a general formalism for constructing locally supersymmetric higher-derivative chiral superfield actions. The theory admits a ghost cond
Externí odkaz:
http://arxiv.org/abs/1212.2185
Publikováno v:
Phys.Rev.D86,123510,2012
It was recently demonstrated that, when coupled to N=1 supergravity, the Dirac-Born-Infeld (DBI) action constructed from a single chiral superfield has the property that when the higher-derivative terms become important, the potential becomes negativ
Externí odkaz:
http://arxiv.org/abs/1208.0752