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Global and Local Stability for Ghosts Coupled to Positive Energy Degrees of Freedom
Cédric Deffayet, Aaron Held, Shinji Mukohyama +1
Negative kinetic energies correspond to ghost degrees of freedom, which are potentially of relevance for cosmology, quantum gravity, and high energy physics. We present a novel wid…
Ghosts without runaway
Cédric Deffayet, Shinji Mukohyama, Alexander Vikman
We present a simple class of mechanical models where a canonical degree of freedom interacts with another one with a negative kinetic term, i.e. with a ghost. We prove analytically…
Counting the degrees of freedom of generalized Galileons
Cedric Deffayet, Gilles Esposito-Farese, Daniele A. Steer
We consider Galileon models on curved spacetime, as well as the counterterms introduced to maintain the second-order nature of the field equations of these models when both the met…
An introduction to the Vainshtein mechanism
Eugeny Babichev, Cedric Deffayet
We introduce the Vainshtein mechanism which plays a crucial role in massive gravities, as well as in related theories such as Galileons and their extensions. This mechanism, also k…
A note on "symmetric" vielbeins in bimetric, massive, perturbative and non perturbative gravities
Cedric Deffayet, Jihad Mourad, George Zahariade
We consider a manifold endowed with two different vielbeins and corresponding to two different metrics and . Such a situation arises generi…
On horizon structure of bimetric spacetimes
Cédric Deffayet, Ted Jacobson
We discuss the structure of horizons in spacetimes with two metrics, with applications to the Vainshtein mechanism and other examples. We show, without using the field equations, t…