title: Effective potential for quantum scalar fields in a de Sitter geometry.
abstract: We study the quantum theory of an O(N) scalar field on de Sitter geometry at leading order in a nonperturbative 1/N expansion. This resums the infinite series of so-called superdaisy loop diagrams. We obtain the de Sitter symmetric solutions of the corresponding, properly renormalized, dynamical field equations and compute the complete effective potential. Because of its self-interactions, the field acquires a strictly positive square mass which screens potential infrared divergences. Moreover, strongly enhanced ultralong-wavelength fluctuations prevent the existence of a spontaneously broken symmetry state in any dimension.
authors.affiliation: Astro-Particule et Cosmologie, Université Paris 7-Denis Diderot, 10 rue Alice Domont et Léonie Duquet, 75205 Paris cedex 13, France.
authors.forename: Julien
authors.initials: J
authors.lastname: Serreau