Massless fields in the static de Sitter space: Exact solutions and choice of the vacuum states

Abstract

Investigations of quantum fields in the de Sitter space have a long history (a bibliography of studies made up to 1981 can be found in the monograph of [i]). Being a curved sPace with maximal symmetry, the de Sitter space makes it possible to construct explicitly a quantum theory of free fields and also some models of interacting fields and investigate effects associated with the influence of the gravitational field on quantum processes. The de Sitter space is an example of a manifold that possesses an event horizon -the cosmological horizon. In the behavior of quantum fields in this space there is an organic intertwining of thermal effects (due to the finiteness of the Hawking temperature [2] associated with the cosmological horizon) with the effects of acceleration and curvature. It is no surprise that problems of quantum field theory in de Sitter space, which are of fundamental interest, have long attracted attention. In recent years a new stimulus to such investigations has been given by the appearance of the theory of an inflationary universe [3,4].