Are all perturbations created equal? An analysis of the WMAP 5- and 7-year data without inflationary prejudice

TL;DR

This paper critically examines claims of detecting primordial tensor perturbations in WMAP data, concluding that no such signals are present at detectable levels when analyzed carefully, and clarifies the theoretical debate on inflationary spectra.

Contribution

The paper provides a detailed reanalysis of WMAP data, challenging previous claims of tensor mode detection and clarifying the theoretical basis of scalar and tensor spectrum calculations.

Findings

No detectable primordial tensor perturbations in WMAP data

Reanalysis refutes previous semi-significant claims

Clarifies the theoretical debate on inflationary spectra

Abstract

We submit recent claims of a semi-significant detection of primordial tensor perturbations in the WMAP data to a closer scrutiny. Our conclusion is in brief that no such mode is present at a detectable level once the analysis is done more carefully. These claims have their root in a brief debate in the late 1990s about the standard calculation of the scalar and tensor spectra in standard inflationary theory, where Grishchuk and collaborators claimed that their amplitudes should be roughly equal. We give a brief summary of the debate and our own reasons for why the standard calculation is correct.