Self-energies of a minimally coupled scalar field with quartic and trilinear
interactions are calculated in a de Sitter background, using a position space
propagator. For quartic interactions, we recover earlier results for the
seagull diagram, namely that it contributes an effective mass for the scalar
field at leading order in the infrared enhancement in a steady-state de Sitter
background. We further show that the sunset diagram also contributes to this
effective mass and argue that these two contributions are sufficient in order
to determine a self-consistent dynamical mass. In addition, trilinear
interactions also induce a dynamical mass for the scalar field which we
calculate. Since an interacting scalar field in de Sitter acquires a dynamical
mass through these loop corrections, the infrared divergences of the two-point
correlator are naturally self-regulated.Comment: 16 pages, 4 figure
