Searching for Inflationary Physics with the CMB Trispectrum: 1. Primordial Theory & Optimal Estimators

Fuente: arXiv
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Auteur principal: Philcox, Oliver H. E.
Format: Preprint
Publié: 2025
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author Philcox, Oliver H. E.
author_facet Philcox, Oliver H. E.
contents The primordial four-point function encodes a wealth of information about the inflationary Universe. Despite extensive theoretical work, most models of four-point physics have never been compared to data. In this series, we conduct a detailed analysis of Cosmic Microwave Background temperature and polarization trispectra, searching for a wide variety of phenomena including local effects, self-interactions, curvatons, DBI inflation, gauge fields, solid inflation, scalar field exchange, spinning massive field exchange, chiral physics, point sources, and gravitational lensing. After presenting a suite of separable primordial templates, we derive thirteen quasi-optimal estimators that directly estimate the underlying template amplitudes. These are unbiased, minimum variance, mask-deconvolved, and account for correlations between templates (including with lensing). Each estimator can be efficiently implemented using spherical harmonic transforms, Monte Carlo methods, and optimization techniques, and asymptotes to standard forms in certain limits. In Paper 2, we implement these estimators in public code, and in Paper 3, use them to constrain primordial trispectra with Planck data. This enables a wide variety of tests of inflation, including some of the first direct constraints on cosmological collider physics.
format Preprint
id arxiv_https___arxiv_org_abs_2502_04434
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Searching for Inflationary Physics with the CMB Trispectrum: 1. Primordial Theory & Optimal Estimators
Philcox, Oliver H. E.
Cosmology and Nongalactic Astrophysics
General Relativity and Quantum Cosmology
High Energy Physics - Phenomenology
High Energy Physics - Theory
The primordial four-point function encodes a wealth of information about the inflationary Universe. Despite extensive theoretical work, most models of four-point physics have never been compared to data. In this series, we conduct a detailed analysis of Cosmic Microwave Background temperature and polarization trispectra, searching for a wide variety of phenomena including local effects, self-interactions, curvatons, DBI inflation, gauge fields, solid inflation, scalar field exchange, spinning massive field exchange, chiral physics, point sources, and gravitational lensing. After presenting a suite of separable primordial templates, we derive thirteen quasi-optimal estimators that directly estimate the underlying template amplitudes. These are unbiased, minimum variance, mask-deconvolved, and account for correlations between templates (including with lensing). Each estimator can be efficiently implemented using spherical harmonic transforms, Monte Carlo methods, and optimization techniques, and asymptotes to standard forms in certain limits. In Paper 2, we implement these estimators in public code, and in Paper 3, use them to constrain primordial trispectra with Planck data. This enables a wide variety of tests of inflation, including some of the first direct constraints on cosmological collider physics.
title Searching for Inflationary Physics with the CMB Trispectrum: 1. Primordial Theory & Optimal Estimators
topic Cosmology and Nongalactic Astrophysics
General Relativity and Quantum Cosmology
High Energy Physics - Phenomenology
High Energy Physics - Theory
url https://arxiv.org/abs/2502.04434