COT5 - Quantum Cosmology and Quantum Effects in the Early Universe |
Speaker_ |
Toporensky, Alexey |
Talk _ |
Cosmological dynamics with vacuum polarization |
Abstract _ |
We consider de Sitter stability in modified gravity theories with respect to vacuum polarization. We assume that an analog of the Friedmann equation in the theory under consideration has the form $H=f(\rho)$, where $H$ is the Hubble parameter, $\rho$ is the matter density. After adding the vacuum polarization terms, this algebraic equation becomes a differential one. We write down eigenvalues of corresponding dynamical system in a de Sitter point, and show that stability of de Sitter solution depends on the sign of $df/d\rho$. A de Sitter point located at a phantom branch (where $df/d\rho < 0$) is unstable with respect to vacuum polarization. |