CMBPol Mission Concept Study: Probing Inflation with CMB Polarization

TL;DR

This paper discusses how precise measurements of CMB polarization, especially B-modes, can reveal details about the inflationary epoch, including energy scales and physics at the Planck scale, through future satellite experiments.

Contribution

It provides a comprehensive analysis of how CMB polarization measurements can distinguish between inflationary models and forecasts the sensitivity of future satellite missions.

Findings

Detection of primordial B-modes indicates high-energy inflation.

CMB measurements constrain inflationary parameters and physics at the Planck scale.

Forecasts show future experiments can significantly improve constraints.

Abstract

We summarize the utility of precise cosmic microwave background (CMB) polarization measurements as probes of the physics of inflation. We focus on the prospects for using CMB measurements to differentiate various inflationary mechanisms. In particular, a detection of primordial B-mode polarization would demonstrate that inflation occurred at a very high energy scale, and that the inflaton traversed a super-Planckian distance in field space. We explain how such a detection or constraint would illuminate aspects of physics at the Planck scale. Moreover, CMB measurements can constrain the scale-dependence and non-Gaussianity of the primordial fluctuations and limit the possibility of a significant isocurvature contribution. Each such limit provides crucial information on the underlying inflationary dynamics. Finally, we quantify these considerations by presenting forecasts for the sensitivities of a future satellite experiment to the inflationary parameters.