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Cosmic Microwave Background from Effective Field Theory

1
Quantum Gravity and Unified Theory and Theoretical Cosmology Group, Max Planck Institute for Gravitational Physics (Albert Einstein Institute), Am Mühlenberg 1, 14476 Potsdam-Golm, Germany
2
Inter-University Centre for Astronomy and Astrophysics, Post Bag 4, Ganeshkhind, Pune 411007, India
NOTE: This project is the part of the non-profit virtual international research consortium “Quantum Structures of the Space-Time & Matter”.
Universe 2019, 5(6), 155; https://doi.org/10.3390/universe5060155
Received: 26 April 2019 / Revised: 6 June 2019 / Accepted: 17 June 2019 / Published: 19 June 2019
(This article belongs to the Special Issue The Cosmological Constant Puzzle)
In this work, we study the key role of generic Effective Field Theory (EFT) framework to quantify the correlation functions in a quasi de Sitter background for an arbitrary initial choice of the quantum vacuum state. We perform the computation in unitary gauge, in which we apply the Stückelberg trick in lowest dimensional EFT operators which are broken under time diffeomorphism. In particular, using this non-linear realization of broken time diffeomorphism and truncating the action by considering the contribution from two derivative terms in the metric, we compute the two-point and three-point correlations from scalar perturbations and two-point correlation from tensor perturbations to quantify the quantum fluctuations observed in the Cosmic Microwave Background (CMB) map. We also use equilateral limit and squeezed limit configurations for the scalar three-point correlations in Fourier space. To give future predictions from EFT setup and to check the consistency of our derived results for correlations, we use the results obtained from all classes of the canonical single-field and general single-field P ( X , ϕ ) model. This analysis helps us to fix the coefficients of the relevant operators in EFT in terms of the slow-roll parameters and effective sound speed. Finally, using CMB observations from Planck we constrain all these coefficients of EFT operators for the single-field slow-roll inflationary paradigm. View Full-Text
Keywords: effective field theories; cosmology of theories beyond the SM; quantum field theory of de Sitter space effective field theories; cosmology of theories beyond the SM; quantum field theory of de Sitter space
MDPI and ACS Style

Choudhury, S. Cosmic Microwave Background from Effective Field Theory. Universe 2019, 5, 155.

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