<p>Cosmological correlators are important observables in cosmology. They are often approximated by de Sitter space correlators. In this paper, we give a first precise diagrammatical computation of higher loop diagrams to all orders for a conformally coupled scalar in four dimensions. We show that, in contrast to flat space, diagrams of necklace topology do not resum using the natural application of de Sitter-invariant regularization and are thus hard to evaluate. We propose a modification to the UV-regularization of the loops, compatible with de Sitter invariance, but much easier to work with. The modified diagrams can be resummed to give a glimpse at non-perturbative effects for de Sitter correlators. Furthermore, they fit nicely with recently proposed cosmological dressing rules.</p>

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Resummation of cosmological correlators and their UV-regularization

  • Matthias Nowinski,
  • Ivo Sachs

摘要

Cosmological correlators are important observables in cosmology. They are often approximated by de Sitter space correlators. In this paper, we give a first precise diagrammatical computation of higher loop diagrams to all orders for a conformally coupled scalar in four dimensions. We show that, in contrast to flat space, diagrams of necklace topology do not resum using the natural application of de Sitter-invariant regularization and are thus hard to evaluate. We propose a modification to the UV-regularization of the loops, compatible with de Sitter invariance, but much easier to work with. The modified diagrams can be resummed to give a glimpse at non-perturbative effects for de Sitter correlators. Furthermore, they fit nicely with recently proposed cosmological dressing rules.