DHOST Bounce
Abstract
We present a new class of nonsingular bounce cosmology free from instabilities, using a single scalar field coupled to gravity within the framework of the Degenerate Higher-Order Scalar-Tensor (DHOST) theories. In this type of scenarios, the gradient instability that widely exists in nonsingular bounce cosmologies in the framework of scalar-tensor and Horndeski/Galileon theories is removed by the effects of new operators introduced by the DHOST, due to the modification that they later bring about to the dispersion relation of perturbations. Hence, our results demonstrate that there is indeed a loophole for this type of bounce scenarios to be free from pathologies when primordial perturbations evolve through the bounce phase, and thus the theoretical {\it no-go} theorem for nonsingular bounce cosmology of Horndeski/Galileon theories can be delicately evaded in DHOST extensions.
Keywords
Cite
@article{arxiv.2002.08269,
title = {DHOST Bounce},
author = {Amara Ilyas and Mian Zhu and Yunlong Zheng and Yi-Fu Cai and Emmanuel N. Saridakis},
journal= {arXiv preprint arXiv:2002.08269},
year = {2020}
}
Comments
23 pages, 6 main figures, comments are welcome