Interacting Quantum Fields in de Sitter Space

          @misc{ pirsa_PIRSA:10100073,
            doi = {10.48660/10100073},
            url = {https://pirsa.org/10100073},
            author = {Woodard, Richard},
            keywords = {Cosmology},
            language = {en},
            title = {Interacting Quantum Fields in de Sitter Space},
            publisher = {Perimeter Institute},
            year = {2010},
            month = {oct},
            note = {PIRSA:10100073 see, \url{https://pirsa.org}}
          }
          

Abstract

Infrared logarithms are factors of the logarithm of the inflationary scale factor which arise in quantum field theoretic loop corrections that involve either massless, minimally coupled scalars or gravitons. They have been found by myself and collaborators in 1PI functions and by Steven Weinberg in the power spectrum of primordial perturbations. Because the inflationary scale factor grows so rapidly, infrared logarithms enhance loop corrections far beyond expectations based upon the coupling constant. They also inject time dependence into what are usually static results. For a very long period of inflation this enhancement can grow so large that weak field perturbation theory breaks down. In this talk I explain the physical reasons why infrared logarithms occur, I review the computations in which they have been seen and I describe Starobinskii's technique for evolving past the breakdown of perturbation theory. I also comment on the potential of infrared logarithms to change our understanding of inflationary cosmology.