Quantum field theory on curved spacetime and the standard cosmological model

TL;DR

This review connects algebraic quantum field theory on curved spacetime to cosmological models, demonstrating how quantum states can reproduce the perfect fluid form of the energy-momentum tensor, with implications for dark radiation.

Contribution

It provides a detailed route from fundamental quantum field theory principles to phenomenological cosmological applications, including explicit state constructions.

Findings

Existence of quantum states with perfect fluid energy-momentum tensor

Quantitative match with standard cosmological model assumptions

Potential implications for dark radiation phenomena

Abstract

The aim of this review is to outline a full route from the fundamental principles of algebraic quantum field theory on curved spacetime in its present-day form to explicit phenomenological applications which allow for comparison with experimental data. We give a brief account on the quantization of the free scalar field and its Wick powers in terms of an algebra of functionals on configuration space. Afterwards we demonstrate that there exist states on this algebra in which the energy momentum tensor is qualitatively and quantitatively of the perfect fluid form assumed in the standard model of cosmology up to small corrections. We indicate the potential relevance of one of these corrections for the actively debated phenomenon of Dark Radiation.