• causality
• finiteness
• gravitation
• Kuzmin
• nonlocal
• quantum gravity
• renormalizability
• unitarity

In this thesis we study a way to incorporate gravity in quantum field theory, only by breaking the principle of locality. We examine Kuz'min’s nonlocal theory of gravity, that was proposed in 1989 and amended with some additional hypotheses in the last few years. We give an original, compound demonstration of its super-renormalizability and prove that, with a suitable choice of the nonlocal functions, only one loop diagrams diverge and in the ultraviolet regime the nonlocal theory resembles a higher derivative one. We also explore the issues of unitarity and causality for local gauge theories and the difficulties that arise when they are generalized to nonlocal theories. Finally, we add another requirement to Kuz’min’s theory: the finiteness, that is the possibility to eliminate the divergences by adding a potential at least cubic in the graviton field. We directly compute the divergences in the case of a correction that is quartic in Riemann tensor and then give a general method of dealing with potentials that are at least quartic in the graviton field.