CMB from EFT

Understand

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 St$\ddot{\text{u}}$ckelberg 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.