Hyperbolicity Constraints in Extended Gravity Theories

Yotam Sherf

We study the characteristic structure of the Einstein-Hilbert (EH) action when modifications of the form of $R^2,R_{\mu \nu }^2$, $R_{\mu \nu \rho \sigma }^2$ and $C_{\mu \nu \rho \sigma }^2$ are included. We show th…