The cosmological collider in $R^2$ inflation

Fuente: arXiv
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Auteur principal: Wu, Yi-Peng
Format: Preprint
Publié: 2024
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author Wu, Yi-Peng
author_facet Wu, Yi-Peng
contents Starobinsky's $R^2$ inflation manifests a best-fit scenario for the power spectrum of primordial density fluctuations. Observables derived from the slow-roll picture of the $R^2$ model in the Einstein frame relies on the conformal transformation of the metric, which inevitably induces a unique exponential-type couplings of the rolling scalaron with all matter fields during inflation. The "large-field" nature of the $R^2$ model further invokes non-negligible time and scale dependence to the matter sector through such an exponential coupling, modifying not only the dynamics of matter perturbations on superhorizon scales but also their decay rates. In this work, we identify the simplest observable of the cosmological collider physics built in the background of $R^2$ inflation, focusing on the so-called "quantum primordial clock" signals created by the non-local propagation of massive scalar perturbations. Our numerical formalism based on the unique conformal coupling can have extended applications to (quasi-)single-field inflationary models with non-trivial couplings to gravity or models originated from the $f(R)$ modification of gravity.
format Preprint
id arxiv_https___arxiv_org_abs_2404_05031
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle The cosmological collider in $R^2$ inflation
Wu, Yi-Peng
Cosmology and Nongalactic Astrophysics
General Relativity and Quantum Cosmology
Starobinsky's $R^2$ inflation manifests a best-fit scenario for the power spectrum of primordial density fluctuations. Observables derived from the slow-roll picture of the $R^2$ model in the Einstein frame relies on the conformal transformation of the metric, which inevitably induces a unique exponential-type couplings of the rolling scalaron with all matter fields during inflation. The "large-field" nature of the $R^2$ model further invokes non-negligible time and scale dependence to the matter sector through such an exponential coupling, modifying not only the dynamics of matter perturbations on superhorizon scales but also their decay rates. In this work, we identify the simplest observable of the cosmological collider physics built in the background of $R^2$ inflation, focusing on the so-called "quantum primordial clock" signals created by the non-local propagation of massive scalar perturbations. Our numerical formalism based on the unique conformal coupling can have extended applications to (quasi-)single-field inflationary models with non-trivial couplings to gravity or models originated from the $f(R)$ modification of gravity.
title The cosmological collider in $R^2$ inflation
topic Cosmology and Nongalactic Astrophysics
General Relativity and Quantum Cosmology
url https://arxiv.org/abs/2404.05031