Schwinger-Keldysh diagrammatics for primordial perturbations
By Xingang Chen, Yi Wang, Z. Xianyu. 2017
178 citations recorded by the source corpus.
We present a systematic introduction to the diagrammatic method for practical calculations in inflationary cosmology, based on Schwinger-Keldysh path integral formalism. We show in particular that the diagrammatic rules can be derived directly from a classical Lagrangian even in the presence of derivative couplings. Furthermore, we use a quasi-single-field inflation model as an example to show how this formalism, combined with the trick of mixed propagator, can significantly simplify the calculation of some in-in correlation functions. The resulting bispectrum includes the lighter scalar case (m<3H/2) that has been previously studied, and the heavier scalar case (m>3H/2) that has not been explicitly computed for this model. The latter provides a concrete example of quantum primordial standard clocks, in which the clock signals can be observably large.
Subfields: Astronomy and Astrophysics, Statistical and Nonlinear Physics
View Paper: https://www.semanticscholar.org/paper/4929cad9b33af6ebb306435eb6bdf0ff74aa5e06
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In Statistical and Nonlinear Physics
Citations in the corpus
- A Mellin space approach to cosmological correlators (2019, unknown): “[43–47].”
- The Cosmological Optical Theorem (2020, unknown): “For non-derivative interactions (it is suggested in [54] that this holds for all interactions), the integral gives Ψ[φ̄; η0] = N lim η→−∞ ∫”
- Bootstrapping inflationary correlators in Mellin space (2019, background): “The first applications of this formalism to the calculation of cosmological correlation functions include [40, 97]; for clear pedagogical reviews see [52, 54, 55].”