5 research outputs found
Gravitational waves in an anomaly-induced inflation
The behaviour of gravitational waves in the anomaly-induced inflationary
phase is studied. The metric perturbations exhibit a stable behaviour, with a
very moderate growth in the amplitude of the waves. The spectral indice is
computed, revealing an almost flat spectrum.Comment: 4 pages. Talk presented at IRGA 2003 (Renormalization Group and
Anomalies in Gravitation and Cosmology, Ouro Preto, Brazil, 16-23 March,
2003
On the stability of the anomaly-induced inflation
We analyze various phases of inflation based on the anomaly-induced effective
action of gravity (modified Starobinsky model), taking the cosmological
constant Lambda and k=0, +/- 1 topologies into account. The total number of the
inflationary e-folds may be enormous, but at the last 65 of them the inflation
greatly slows down due to the contributions of the massive particles. For the
supersymmetric particle content, the stability of inflation holds from the
initial point at the sub-Planck scale until the supersymmetry breaks down.
After that the universe enters into the unstable regime with the eventual
transition into the stable FRW-like evolution with small positive cosmological
constant. It is remarkable, that all this follows automatically, without
fine-tuning of any sort, independent on the values of Lambda and k. Finally, we
consider the stability under the metric perturbations during the last 65
e-folds of inflation and find that the amplitude of the ones with the
wavenumber below a certain cutoff has an acceptable range.Comment: 27 pages, LaTeX, 8 figures, some misprints correcte
Renormalization Group and Decoupling in Curved Space: II. The Standard Model and Beyond
We continue the study of the renormalization group and decoupling of massive
fields in curved space, started in the previous article and analyse the higher
derivative sector of the vacuum metric-dependent action of the Standard Model.
The QCD sector at low-energies is described in terms of the composite effective
fields. For fermions and scalars the massless limit shows perfect
correspondence with the conformal anomaly, but similar limit in a massive
vector case requires an extra compensating scalar. In all three cases the
decoupling goes smoothly and monotonic. A particularly interesting case is the
renormalization group flow in the theory with broken supersymmetry, where the
sign of one of the beta-functions changes on the way from the UV to IR.Comment: 27 pages, 8 figure
Bianchi solutions of quadratic gravity
It is believed that soon after the Planck time, Einstein's general relativity
theory should be corrected to an effective quadratic theory. Numerical
solutions for the anisotropic generalization of the Friedmann "open" model for this effective gravity are given. It must be emphasized that although
numeric, these solutions are exact in the sense that they depend only on the
precision of the machine. The solutions are identified asymptotically in a
certain way. It is found solutions which asymptote de Sitter space, Riemann
flat space and a singularity. The question of isotropisation of an initially
anisotropic Universe is of great importance in the context of cosmology.
Although isotropisation is not directly discussed in this present work, we show
that sufficiently small anisotropies, do not increase indefinitely according to
particular quadratic gravity theories. It can be understood as weak
isotropisation, and we stress that this result is strongly dependent on initial
conditions.Comment: version accepted for publication in General Relativity and
Gravitation. arXiv admin note: substantial text overlap with arXiv:1203.688