2025/07/21 by Tuneer Chakraborty, H Ashik, Chakraborty, Tuneer +4 · 1 voice
Physics and Astronomy · #Black Holes and Theoretical Physics #Cosmological constant #Cosmological perturbation theory #Cosmology and Gravitation Theories #Dark Matter and Cosmic Phenomena #De Sitter space #De Sitter universe #FOS: Physical sciences #General Relativity and Quantum Cosmology (gr-qc) #Graviton #High Energy Physics - Theory (hep-th) #Observable #Operator product expansion #Quantum field theory #Quantum gravity #Vacuum state #gr-qc #hep-th
paper · pdf · doi:10.48550/arxiv.2507.15926
published in arXiv (Cornell University) (Cornell University)
openalex publication_date 2025/07/21 · arxiv published 2025/07/21 · arxiv updated 2025/07/21 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/05
We study cosmological correlators in de Sitter quantum gravity in the limit where GN → 0. This limit is distinct from a nongravitational QFT because the gravitational constraints still force states and observables to be de Sitter invariant. We first examine a class of perturbative correlators that, in gauge-fixed form, are represented by the expectation value of a product of elementary fields on the late-time boundary. We formulate Feynman rules for our computations and enumerate some necessary, but not sufficient, conditions that must be imposed on states and operators to avoid group-volume divergences. These correlators are conformally invariant in all allowed perturbative states but never coincide with QFT vacuum-expectation values. For instance, our sample computations yield interesting non-Gaussianities even when the underlying vacuum wavefunction is Gaussian. However, we show that, in the presence of a heavy background state, it is possible to construct a separate class of state-dependent relational observables whose values approximate QFT correlators in the vacuum. This illustrates a key contrast in quantum gravity -- between observables that are microscopically simple and observables whose expectation values in an appropriate background state lead to simple QFT-like correlators.