Palatini approach and large-scale magnetogenesis
Abstract
Large-scale magnetogenesis is analyzed within the Palatini approach when the gravitational action is supplemented by a contribution that is nonlinear in the Einstein-Hilbert term. While the addition of the nonlinear terms does not affect the scalar modes of the geometry during the inflationary phase, the tensor-to-scalar ratio is nonetheless suppressed. In this context it is plausible to have a stiff phase following the standard inflationary stage provided the potential has a quintessential form. The large-scale magnetic fields can even be a fraction of the nG over typical length scales of the order of the Mpc prior to the gravitational collapse of the protogalaxy.
Cite
@article{arxiv.2110.02632,
title = {Palatini approach and large-scale magnetogenesis},
author = {Massimo Giovannini},
journal= {arXiv preprint arXiv:2110.02632},
year = {2021}
}
Comments
41 pages, 5 figures; corrected typos to match the version to be published in JCAP