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MP: Fachverband Theoretische und Mathematische Grundlagen der Physik

MP 9: Quantum gravity (joint session MP/GR)

MP 9.2: Hauptvortrag

Donnerstag, 24. März 2022, 11:30–12:00, MP-H5

Quantum fields propagating on curved backgrounds and their influence on spacetime curvature — •Nicola Pinamonti — Department of Mathematics, University of Genova, Italy

We shall review the theory of quantum fields propagating on curved backgrounds in the semiclassical approximation. Within this approximation matter is described by quantum fields propagating on a classical curved spacetime and their influence on spacetime curvature is taken into account by means of semiclassical Einstein equations. Typical known effects in this approximation are particle creation on cosmological spacetime, Hawking radiation in the case of black hole backgrounds and their evaporation. The semiclassical analysis we would like to present requires a careful study of the form of the correlation functions of the state which describes matter. The thorough analysis of their ultraviolet divergences and their renormalization is necessary to obtain meaningful expressions for the expectation values of the matter stress energy tensor. The resulting stress energy tensor will have nontrivial effects on the curvature on cosmological spacetimes too. In the latter case, semiclassical Einstein equations give origin to a well posed dynamical system provided the quantum state for matter is chosen in an appropriate way. The question of existence of exact solutions of such system will be discussed and some implication for cosmology will be presented. In the case of black hole physics, exploiting the stress tensor properties, we will give a local model of black hole evaporation.