Classical Ghosts and the Cosmological Constant

By Takayuki Hirayama, University of Toronto

For a large region of parameter space involving the cosmological constant and mass parameters, we discuss spacetime solutions that are effectively Minkowskian on large time and distance scales. A negative energy fluid is involved, resulting in a scale factor oscillating about a constant, with a frequency determined by the size of a negative cosmological constant. Gravity itself induces a coupling between the ghost-like and normal fields, and we find that this results in stochastic rather than unstable behavior.