I will discuss several aspects of loop effects in single and multifield inflation.
In the original CPT theorem, one is restricted to flat space and is unable to make converse statements. In this talk, I will show how we can reformulate the CPT theorem using a symmetry argument to make converse statements and generalise it to beyond flat space. This in turn allows us to make a non-perturbative statement of unitarity in cosmology. I will show that this applies to the...
We compute loop integrals of in-in correlators in dS for scalar theories and comment on the nature of the functions encountered and the simplicity observed compared to loops of wave functions (which can be equivalently thought of as AdS correlators).
This is based on upcoming work and 2312.13803, 2408.00074
In this talk, I present a novel connection between cosmological correlators and flat-space Feynman diagrams in momentum space. Focusing on Witten diagrams with heavy internal lines and light external legs, I establish a Massive Flat Space (MFS) limit. In this limit, such heavy diagrams simplify to contact graphs with a vertex factor equal to the amputated n-point diagram in flat space. As...
I will discuss the ratio of the one-loop to the tree-level power spectrum of curvature fluctuations in a toy model of USR inflation, with the aim of discerning if perturbation theory breaks in related scenarios of PBH dark matter.
We study the cancellation of quantum corrections on the superhorizon curvature perturbations from subhorizon physics beyond the single-clock inflation from the viewpoint of the cosmological soft theorem. As an example, we focus on the transient ultra-slow-roll inflation scenario and compute the one-loop quantum corrections to the power spectrum of curvature perturbations taking into account...
We examine one-loop corrections from small-scale curvature perturbations to the superhorizon-limit ones in single-field inflation models, which have recently caused controversy. We consider the case where the Universe experiences transitions of slow-roll (SR) → intermediate period → SR. The intermediate period can be an ultra-slow-roll period or a resonant amplification period, either of which...
We use the in-in formalism to compute the non-Gaussian corrections to the energy density and anisotropies of gravitational waves induced after an ultra-slow-roll phase of inflation by using a diagrammatic approach and present the corresponding Feynman rules. Our two-loop calculation includes both the intrinsic non-Gaussianity of the inflaton perturbation $\delta\phi$ and the non-Gaussianity...
In this talk, I will explore the effects of renormalization on the amplitude of the inflationary spectra at scales measurable in the cosmic microwave background.
Via a gauge-invariant analysis, I will explain why the standard prediction for the spectra on superhorizon scales is a late-time attractor while they are UV finite at all times. This result is independent of the equation of state...
In the context of slow-roll inflation, deviations from a purely de Sitter background are expected and are both separate and complementary to the loop corrections in various inflationary scenarios. In this talk, I propose to go over some of the most up-to-date computations of the inflationary scalar and tensor slow-roll power spectra at next-to-next-to-next to leading order (N3LO), fully...
Currently, the study of cosmological correlation functions is extremely favored, and a large number of new techniques are being developed. I will discuss a less-fashioned but very efficient technique to calculate the loop corrections to the correlation function in the long-wavelength approximation. By employing the Yang-Feldman-type equation, we compute the two-point correlation function up to...
I plan to discuss 1) what can be learnt from the interacting field in Euclidean dS space, 2) the method of region applied to calculate the late-time asymptotics from (IR-divergent) loop diagrams of the massless field, 3) matching to Soft dS Effective Theory.
