The Phantom menaced: Constraints on low-energy effective ghosts

By J. Cline, Sangyong Jeon, Guy D. Moore. 2003

615 citations recorded by the source corpus.

It has been suggested that a scalar field with negative kinetic energy, or ``ghost,'' could be the source of the observed late-time cosmological acceleration. Naively, such theories should be ruled out by the catastrophic quantum instability of the vacuum. We derive phenomenological bounds on the Lorentz-violating ultraviolet cutoff $\ensuremath{\Lambda}$ which must apply to low-energy effective theories of ghosts, in order to keep the instability at unobservable levels. Assuming only that ghosts interact at least gravitationally, we show that $\ensuremath{\Lambda}\ensuremath{\lesssim}3\mathrm{MeV}$ for consistency with the cosmic gamma ray background. We also show that theories of ghosts with a Lorentz-conserving cutoff are completely excluded.

Subfields: Astronomy and Astrophysics, Nuclear and High Energy Physics

View Paper: https://www.semanticscholar.org/paper/5669c9e47aa8db5e8678146cdf455755038bd433

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Citations in the corpus

Ghost condensation and a consistent infrared modification of gravity (2003, background): “Other possible decays and constraints were considered in Ref. [19, 20 ].”
Approaches to understanding cosmic acceleration (2009, background): “Such a question has been studied in some detail by several authors [86, 87].”
f(T) teleparallel gravity and cosmology (2015, background): “the fact that the phantom regime can be described without the need of phantom fields, which have ambiguous quantum behavior [330], is a significant advantage.”
Modified Gravity and Cosmology (2011, background): “When a physical ghost is present one has a choice: Accept the existence of negative norm states and abandon unitarity, or else accept that the energy eigenvalues of the ghost are negative [317].”
Beyond the Cosmological Standard Model (2014, neutral): “Figure 22: In theories with a ghostly field, the vacuum is unstable to rapid pair production of ghost particles and healthy particles, causing the theory to be ill-defined (See [96, 1012]).”
Aspects of quadratic gravity (2015, background): “However, with the above +i prescription for the ghost, unitarity is maintained at the cost of propagation of negative energy forward in time [26].”