1202.1239 (Jaume Garriga et al.)

Living with ghosts in Lorentz invariant theories    [PDF]

Jaume Garriga, Alexander Vilenkin

We show that theories with ghosts may have a long lived vacuum state even if
all interactions are Lorentz preserving. In space-time dimension $D>2$, this is
only possible if we assume that the interaction between ordinary matter and the
ghost sector is soft in the UV, so that it can be described in terms of
non-local form factors rather than point-like vertices.

View original: http://arxiv.org/abs/1202.1239