Big-Bounce in projectively invariant Nieh-Yan models: the Bianchi I case
Abstract
We show that the Nieh-Yan topological invariant breaks projective symmetry and loses its topological character in presence of non vanishing nonmetricity. The notion of the Nieh-Yan topological invariant is then extended to the generic metric-affine case, defining a generalized Nieh-Yan term, which allows to recover topologicity and projective invariance, independently. As a concrete example a class of modified theories of gravity is considered and its dynamical properties are investigated in a cosmological setting. In particular, bouncing cosmological solutions in Bianchi I models are derived. Finite time singularities affecting these solutions are analysed, showing that the geodesic completeness and the regular behavior of scalar perturbations in these space-times are not spoiled.
Keywords
Cite
@article{arxiv.2111.03338,
title = {Big-Bounce in projectively invariant Nieh-Yan models: the Bianchi I case},
author = {Flavio Bombacigno and Simon Boudet and Gonzalo J. Olmo and Giovanni Montani},
journal= {arXiv preprint arXiv:2111.03338},
year = {2021}
}
Comments
To appear in the Proceedings of the 16th Marcel Grossmann meeting (5-10 July, 2021)