Seminar〝Hyperfluids and Non-Riemannian Effects in Cosmology〞

Star-UBB Seminar Series:- Hyperfluids and Non-Riemannian Effects in Cosmology

The speaker investigates the cosmological aspects of the most general parity preserving Metric-Affine Gravity theory quadratic in torsion and non-metricity in the presence of a cosmological hyperfluid. The latter is a generalization of the usual Perfect Fluid notion that includes also a non-vanishing hypermomentum tensor that is compatible with the Cosmological Principle and encodes the microscopic characteristics of matter. Then, the equations of motion are obtained by varying the action with respect to the metric and the independent affine connection. Subsequently, considering a Friedmann-Lemaître-Robertson-Walker background, he derives the most general form of the modified Friedmann equations for the full quadratic theory. He then focuses on a characteristic sub-case involving only two quadratic contributions given in terms of torsion and non-metricity vectors. In this setup, studying the modified Friedmann equations along with the conservation laws of the perfect cosmological hyperfluid, the speaker provides exact solutions both for purely dilation and for purely spin hypermomentum sources. He then discusses the physical consequences of our model and the prominent role of torsion and non-metricity in this cosmological setup.

時間:2023.04.27(四) 16:00~17:00
頻道:Zoom ID:853-7454-4159 ←
講者:Damianos Iosifidis (Tartu University, Estonia)


Scientific and Technological Advanced Research- Babeș-Bolyai University(Star-UBB) Seminar Series in Gravitation, Cosmology and Astrophysics

Presently a period of rapid and intense change are being witnessed in our understanding of the gravitational force, at a rate that is quickly increasing since the important observational discoveries of the late 1990s. With the advent of new observational techniques, the emergence of important cosmological and astrophysical paradigms can be seen that lead to a deep change in our understanding of the Universe. Astronomical observations strongly suggest that at large scales the force of gravity may not behave according to standard general relativity, and that a generalization of the gravitational action, either at the geometric level, or at the matter level, may be required for a full understanding of the gravitational interaction.

The goal of the present seminar is to bring Theoretical Gravitational Physics closer to the observations and experiments, and to discuss current topics in general relativity, high-energy physics, astrophysics and cosmology.


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