Scalar field correlator in de Sitter space at next-to-leading order in a 1/N expansion

Understand

We study the dynamics of light quantum scalar fields in de Sitter space on superhorizon scales.

• We compute the self-energy of an O(N) symmetric theory at next-to-leading order in a 1/N expansion in the regime of superhorizon momenta, and we obtain an exact analytical solution of the corresponding Dyson-Schwinger equations for the two-point correlator.
• This amounts to resumming the infinite series of nonlocal self-energy insertions, which typically generate spurious infrared and/or secular divergences.
• The potentially large de Sitter logarithms resum into well-behaved power laws from which we extract the field strength and mass renormalization.