New results on de Sitter quantum field theory

We describe a new approach to d-dimensional de Sitter quantum field theory. This approach allows a complete characterization of the preferred de Sitter vacua for Klein-Gordon field theories in terms of the analyticity properties of the two-point function, for which we provide a new integral representation. The latter relies on a natural basis of de Sitter plane-waves, which are holomorphic in tubular domains of the complexified de Sitter space-time, Finally we discuss a possible general approach to interacting de Sitter field theories, which, among other properties, justifies the ''Wick rotation'' to the ''euclidean sphere''.