http://arxiv.org/abs/1808.01170
We show that a nonsingular bounce, free of ghosts and gradient instabilities, can be realized in the framework of Horndeski or generalized Galileon cosmology. In particular, we first review that the theoretical no-go theorem, which states that the above is impossible, is based on a very strong assumption that a particular quantity cannot be discontinuous during the bounce. However, as we show in the present work, not only this assumption can be violated in a general Horndeski/Galileon scenario, but also it is necessarily violated at the bounce point within the subclass of Horndeski/Galileon gravity in which $K(\phi,X)$ becomes zero at $X=0$. Finally, in order to make the analysis more transparent we provide an explicit example where a nonsingular bounce can be achieved, without manifest theoretical pathologies.
S. Banerjee, Y. Cai and E. Saridakis
Mon, 6 Aug 18
7/33
Comments: 7 pages, 6 figures