Regularity theory and global existence of small data solutions to semi-linear de Sitter models with power non-linearity

Abstract

In this paper we study the Cauchy problem for semi-linear de Sitter models with power non-linearity. The model of interest is \[ ϕ_{tt} - e^{-2t} Δϕ+ nϕ_t+m^2ϕ=|ϕ|^p,\quad (ϕ(0,x),ϕ_t(0,x))=(f(x),g(x)),\] where $m^2$ is a non-negative constant. We study the global (in time) existence of small data solutions. In particular, we show the interplay between the power $p$, admissible data spaces and admissible spaces of solutions (in weak sense, in sense of energy solutions or in classical sense).

32 pages