Renormalization freedom in de Sitter spacetime
By considering a Quantum Field Theory with time-dependent backgrounds the time-translational symmetry of the Lagrangian may be broken. In my talk I would like to discuss renormalization in curved spacetime using the CTP formalism. In particular, I will show the results for simple diagrams, where explicit calculations are still possible. Connections with the renormalization as an extension of distributions will be pointed out.