Ghosts without runaway instabilities

In this talk, Prof. Cedric Deffayet (Laboratoire de Physique de l’École Normale Supérieure, ENS, Université PSL, CNRS, and Sorbonne Université, Université Paris Cité, Paris, France) will discuss simple mechanical models with a ghost interacting with a positive energy degree of freedom, and yet, the phase-space motion can be shown analytically and numerically to be fully stable.