Infrared dynamics in de Sitter space from Schwinger–Dyson equations

摘要: Abstract We study the two-point correlator of an O ( N ) scalar field with quartic self-coupling in de Sitter space. For light fields units expansion rate, perturbation theory is plagued by large logarithmic terms for superhorizon momenta. show that a proper treatment infinite series self-energy insertions through Schwinger–Dyson equations resums these infrared logarithms into power laws. provide exact analytical solution momenta when computed at two-loop order. Our findings encompass previously obtained results using either stochastic or Euclidean approaches. The exhibits rich structure superposition free-field-like extract mass and field-strength renormalization factors from asymptotic behavior. latter are nonperturbative coupling case vanishing tree-level mass.