Zobrazeno 1 - 10
of 139
pro vyhledávání: '"Kofman, Lev"'
Publikováno v:
JCAP 1105:011,2011
This article investigates the stability of a generic Kasner spacetime to linear perturbations, both at late and early times. It demonstrates that the perturbation of the Weyl tensor diverges at late time in all cases but in the particular one in whic
Externí odkaz:
http://arxiv.org/abs/1102.3071
Publikováno v:
Astrophys.J.726:64,2011
Bulk dark energy properties are determined by the redshift evolution of its pressure-to-density ratio, $w_{de}(z)$. An experimental goal is to decide if the dark energy is dynamical, as in the quintessence (and phantom) models treated here. We show t
Externí odkaz:
http://arxiv.org/abs/1007.5297
Publikováno v:
JCAP 1007:016,2010
We study in detail (p)reheating after multi-field inflation models with a particular focus on N-flation. We consider a variety of different couplings between the inflatons and the matter sector, including both quartic and trilinear interactions with
Externí odkaz:
http://arxiv.org/abs/1005.2196
Publikováno v:
JCAP 0912:021,2009
We study (p)reheating in modular (closed string) inflationary scenarios, with a special emphasis on Kahler moduli/Roulette models. It is usually assumed that reheating in such models occurs through perturbative decays. However, we find that there are
Externí odkaz:
http://arxiv.org/abs/0909.0503
Publikováno v:
Phys.Rev.Lett.103:071301,2009
A new class of non-Gaussian curvature fluctuations \zeta_{pr} (\bx) \equiv \delta N(\chi_i) arises from the post-inflation preheating behaviour of a non-inflaton field \chi_i. Its billiard-like chaotic dynamics imprints regular log-spaced narrow spik
Externí odkaz:
http://arxiv.org/abs/0903.3407
Publikováno v:
Phys.Rev.D80:043501,2009
We propose a qualitatively new mechanism for generating cosmological fluctuations from inflation. The non-equilibrium excitation of interacting scalar fields often evolves into infra-red (IR) and ultra-violet (UV) cascading, resulting in an intermedi
Externí odkaz:
http://arxiv.org/abs/0902.0615
Publikováno v:
JCAP 0903:001,2009
We study the stochastic background of gravitational waves produced from preheating in hybrid inflation models. We investigate different dynamical regimes of preheating in these models and we compute the resulting gravity wave spectra using analytical
Externí odkaz:
http://arxiv.org/abs/0812.2917
Publikováno v:
Phys.Rev.D78:103525,2008
We show that expanding or contracting Kasner universes are unstable due to the amplification of gravitational waves (GW). As an application of this general relativity effect, we consider a pre-inflationary anisotropic geometry characterized by a Kasn
Externí odkaz:
http://arxiv.org/abs/0807.1335
Autor:
Buchel, Alex, Kofman, Lev
Publikováno v:
Phys.Rev.D78:086002,2008
String theory compactification involves manifolds with multiple warp factors. For cosmological applications, one often introduces a short, high-energy inflationary throat, and a long,low-energy Standard Model throat. It is assumed that at the end of
Externí odkaz:
http://arxiv.org/abs/0804.0584
Autor:
Kofman, Lev, Mukohyama, Shinji
Publikováno v:
Phys.Rev.D77:043519,2008
Usual inflation is realized with a slow rolling scalar field minimally coupled to gravity. In contrast, we consider dynamics of a scalar with a flat effective potential, conformally coupled to gravity. Surprisingly, it contains an attractor inflation
Externí odkaz:
http://arxiv.org/abs/0709.1952