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The present dissertation reviews the coupling of a scalar non-interacting quantum field with the metric of a FLRW (Friedmann-Lemâitre-Robertson-Walker) spacetime, proposed in a work by C. Dappiaggi, K. Fredenhagen and N. Pinamonti. We present methods for the quantization of a real Klein-Gordon field in globally hyperbolic spacetimes and discuss procedures for the point-splitting regularization of the stress-energy tensor. We consider those fields in FLRW spacetimes and point out adiabatic states with mean field fluctuation given by 〈Φ〉 = αm +βR, with α, β being constants that emerge from the regularization procedure. The backreaction of the quantum field provides a diferential equation for the Hubble parameter given by Ḣ(H−H c ) = −(H−H +)(H−H −) with Hc a constant and H± stable critical points of the equation. In this way, this simple model demonstrates that quantum effects may, by themselves, exibit stable de Sitter phases even without an introduction of a cosmological constant by hand. Althoug in a qualitative way, such result shows that, when dealing with the backreaction issue, a careful analysis of the quantization procedures is important for the analysis of cosmological effects of models of quantum field theories in curved spacetimes.

Efeitos cosmológicos induzidos por campos quantizados