2013/11/30 by Benjamin Elder, Austin Joyce, Justin Khoury
Physics and Astronomy · #hep-th #gr-qc #hep-ph
paper · pdf · doi:10.1103/physrevd.89.044027
published as Phys. Rev. D 89, 044027 (2014) · 27 pages, 6 figures. v2: added references, subsection describing cosmological evolution. Version to appear in PRD
arxiv created 2014/01/22 · arxiv updated 2014/02/26
We construct a theory which admits a time-dependent solution smoothly interpolating between a null energy condition (NEC)-satisfying phase at early times and a NEC-violating phase at late times. We first review earlier attempts to violate the NEC and an argument of Rubakov, presented in 1305.2614, which forbids the existence of such interpolating solutions in a single-field dilation-invariant theory. We then construct a theory which, in addition to possessing a Poincaré-invariant vacuum, does admit such a solution. For a wide range of parameters, perturbations around this solution are at all times stable, comfortably subluminal and weakly-coupled. The theory requires us to explicitly break dilation-invariance, so it is unlikely that the theory is fully stable under quantum corrections, but we argue that the existence of a healthy interpolating solution is quantum-mechanically robust.