The phantom menaced: Constraints on lowenergy effective ghosts
Abstract
It has been suggested that a scalar field with negative kinetic energy, or “ghost,” could be the source of the observed latetime cosmological acceleration. Naively, such theories should be ruled out by the catastrophic quantum instability of the vacuum. We derive phenomenological bounds on the Lorentzviolating ultraviolet cutoff Λ which must apply to lowenergy effective theories of ghosts, in order to keep the instability at unobservable levels. Assuming only that ghosts interact at least gravitationally, we show that Λ≲3 MeV for consistency with the cosmic gamma ray background. We also show that theories of ghosts with a Lorentzconserving cutoff are completely excluded.
 Publication:

Physical Review D
 Pub Date:
 August 2004
 DOI:
 10.1103/PhysRevD.70.043543
 arXiv:
 arXiv:hepph/0311312
 Bibcode:
 2004PhRvD..70d3543C
 Keywords:

 98.80.Cq;
 98.70.Vc;
 Particletheory and fieldtheory models of the early Universe;
 Background radiations;
 Astrophysics;
 High Energy Physics  Phenomenology;
 High Energy Physics  Theory
 EPrint:
 4 pages, 2 figures