Remembrance of things past

Nonlinear sigma models on de Sitter background have proved a useful prototype for quantum gravity in summing the large logarithms which arise from loop corrections. We consider a model whose evolution is described, at leading logarithm order, by the trace of the coincident, doubly differentiated scalar propagator. An analytic approximation for this quantity on an arbitrary expansion history is applied to generalize the resummed de Sitter result to any cosmological background which has experienced primordial inflation. In addition to analytic expressions, we present explicit numerical results for the evolution in a plausible expansion history. The large scales of primordial inflation are transmitted to late times.

Automated summary

Nonlinear sigma models on de Sitter background are studied as a prototype for quantum gravity, addressing the issue of large logarithms arising from loop corrections. By considering the trace of the coincident, doubly differentiated scalar propagator, an analytic approximation is used to extend the resummed de Sitter result to any cosmological background with primordial inflation. In addition to analytical expressions, numerical results for an applicable expansion history are presented, showing how the large scales of primordial inflation persist to late times.