The Cosmological Bootstrap: Spinning correlators from symmetries and factorization
By D. Baumann, C. D. Pueyo, A. Joyce, Hayden Lee, G. L. Pimentel. SciPost Physics, 2020
194 citations recorded by the source corpus.
We extend the cosmological bootstrap to correlators involving massless spinning particles, focusing on spin-1 and spin-2. In de Sitter space, these correlators are constrained both by symmetries and by locality. In particular, the de Sitter isometries become conformal symmetries on the future boundary of the spacetime, which are reflected in a set of Ward identities that the boundary correlators must satisfy. We solve these Ward identities by acting with weight-shifting operators on scalar seed solutions. Using this weight-shifting approach, we derive three- and four-point correlators of massless spin-1 and spin-2 fields with conformally coupled scalars. Four-point functions arising from tree-level exchange are singular in particular kinematic configurations, and the coefficients of these singularities satisfy certain factorization properties. We show that in many cases these factorization limits fix the structure of the correlators uniquely, without having to solve the conformal Ward identities. The additional constraint of locality for massless spinning particles manifests itself as current conservation on the boundary. We find that the four-point functions only satisfy current conservation if the s, t, and u-channels are related to each other, leading to nontrivial constraints on the couplings between the conserved currents and other operators in the theory. For spin-1 currents this implies charge conservation, while for spin-2 currents we recover the equivalence principle from a purely boundary perspective. For multiple spin-1 fields, we recover the structure of Yang--Mills theory. Finally, we apply our methods to slow-roll inflation and derive a few phenomenologically relevant scalar-tensor three-point functions.
Subfields: Astronomy and Astrophysics, Nuclear and High Energy Physics
View Paper: https://www.semanticscholar.org/paper/a14a0d5225d08c0984e11ec77df35bdc115853ca
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Citations in the corpus
- The Cosmological Optical Theorem (2020, background): “This is a generalisation of the results in section 6 from [24] to diagrams with multiple vertices.”
- The cosmological bootstrap: weight-shifting operators and scalar seeds (2019, methodology): “37) both raises the spin and lowers the weight at the point 1 and is useful for raising the spin of external fields [57].”
- Building a boostless bootstrap for the bispectrum (2020, methodology): “Indeed, we know from [10, 20] (see also the discussions in [14, 19]) that the ζ bispectrum arises from the “graviton-exchange” scalar trispectrum29 after “putting a leg on the background”, i.”