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Search: authors:"Aleksander Stachowski"

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Starobinsky cosmological model in Palatini formalism

We classify singularities in FRW cosmologies, which dynamics can be reduced to the dynamical system of the Newtonian type. This classification is performed in terms of the geometry of a potential function if it has poles. At the sewn singularity, which is of a finite scale factor type, the singularity in the past meets the singularity in the future. We show that such singularities ...

Cosmological implications of the transition from the false vacuum to the true vacuum state

We study cosmology with running dark energy. The energy density of dark energy is obtained from the quantum process of transition from the false vacuum state to the true vacuum state. We use the Breit–Wigner energy distribution function to model the quantum unstable systems and obtain the energy density of the dark energy parametrization \(\rho _\text {de}(t)\). We also use Krauss ...

Dynamical system approach to running \(\Lambda \) cosmological models

Eur. Phys. J. C Dynamical system approach to running cosmological models Aleksander Stachowski 1 Marek Szydłowski 0 1 0 Mark Kac Complex Systems Research Centre, Jagiellonian University , Ł

Do sewn up singularities falsify the Palatini cosmology?

We investigate further (cf. Borowiec et al. JCAP 1601(01):040, 2016) the Starobinsky cosmological model \(R+\gamma R^2\) in the Palatini formalism with a Chaplygin gas and baryonic matter as a source in the context of singularities. The dynamics reduces to the 2D sewn dynamical system of a Newtonian type (a piece-wise-smooth dynamical system). We demonstrate that the presence of a ...