The Perfect Hyperfluid of Metric-Affine Gravity: The Foundation

TL;DR

This paper introduces the Perfect Hyperfluid as a comprehensive matter model in Metric-Affine Gravity, incorporating microscopic matter properties like spin, shear, and dilation, and explores its cosmological implications.

Contribution

It formulates the foundational structure of the Perfect Hyperfluid, deriving its energy tensors and conservation laws within a non-Riemannian spacetime framework.

Findings

Derived energy tensors for the Hyperfluid

Established conservation laws for the Hyperfluid

Classified possible cosmological fluid configurations

Abstract

We set the foundation and formulate the Perfect (Ideal) Hyperfluid. The latter represents the natural generalization of the usual perfect fluid structure where now the microscopic characteristics of matter (spin, shear, dilation) are also taken into account, sourcing a non-Riemannian arena (i.e spacetime torsion and non-metricity) for Metric-Affine Gravity. We derive the energy tensors of this Hyperfluid structure and subsequently present the conservation laws obeyed by them. Finally, we consider a Cosmological application of this Perfect Hyperfluid and classify some possible forms of this fluid structure.