Application of multisection recursive convolution in 3D FETD-FABC simulations

The multisection recursive convolution (MS-RC) methodology is successfully applied to the finite element time domain floquet absorbing boundary condition modeling of doubly periodic structures. It is shown that late time instability, can be delayed by improving the accuracy of RC and it can be effectively avoided by employing extrapolation

A covariant Lagrangian for stable nonsingular bounce

The nonsingular bounce models usually suffer from the ghost or gradient instabilities, as has been proved recently. In this paper, we propose a covariant effective theory for stable nonsingular bounce, which has the quadratic order of the second order derivative of the field $\phi$ but the background set only by $P(\phi,X)$. With it, we explicitly construct a fully stable nonsingular bounce model for the ekpyrotic scenario.Comment: 12 pages, 6 figures; published in JHEP; an Appendix and references adde