Seminarium "Teoria cząstek elementarnych i kosmologia"

Purely virtual particles, or fakeons, are degrees of freedom of a new type that mediate interactions but cannot appear as external on-shell states. The main application of fakeons is quantum gravity, which can be made both renormalizable and unitary. After discussing the nonrenormalizability of Einstein theory and the non-unitarity of higher-derivative gravity, I will show in detail how to endow quantum field theory with purely virtual particles. Then, I will present the main features of the theory of quantum gravity and show its predictions in inflationary cosmology. Finally, I will conclude with some remarks on fakeons in the context of particle physics.