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Friedmann-like universes with non-metricity

Published version
Peer-reviewed

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Authors

Iosifidis, Damianos  ORCID logo  https://orcid.org/0000-0003-1849-6481
Vogiatzis, Ioannis Georgios 
Tsagas, Christos G 

Abstract

jats:titleAbstract</jats:title>jats:pWe study the potential effects of spacetime non-metricity in cosmology. In the spirit of Einstein–Cartan gravity, but with non-metricity replacing torsion, we consider the Einstein–Hilbert action and assume zero torsion. Adopting certain hyperfluid models, with non-vanishing hypermomentum that can source spacetime non-metricity, we add a matter component into the action and derive the field equations, along with the conservation laws. Applying our formulae to cosmology, we generalize the Friedmann and the Raychaudhuri equations in the presence of non-metricity. Our results show that, in a number of cases, non-metricity can mimic the effects of matter with unconventional equation of state. For instance, specific types of hypermomentum are found to act as an effective stiff fluid, thus opening the possibility that non-metricity could have played a significant role in the early stages of the universe’s evolution. Alternative forms of hypermomentum can dominate the universal dynamics at late times. In either case, the equilibrium moment depends on the initial conditions and it is determined by a simple relation between the matter component and the hyperfluid.</jats:p>

Description

Keywords

5107 Particle and High Energy Physics, 51 Physical Sciences

Journal Title

The European Physical Journal C

Conference Name

Journal ISSN

1434-6044
1434-6052

Volume Title

Publisher

Springer Science and Business Media LLC