Searching for features of a string-inspired inflationary model with cosmological observations

TL;DR

This paper investigates a string-inspired inflationary model with potential modulations that can explain certain anomalies in the CMB power spectrum, suggesting possible observational tests of high-energy physics.

Contribution

It introduces a string theory inspired inflationary model with step-like potential modulations that can account for specific CMB anomalies and makes testable predictions.

Findings

The model explains the power deficit near e2a4 e2a4 20 in the CMB.

It predicts distinctive patterns in temperature-polarization spectra.

The model shows potential for testing high-energy physics effects with future observations.

Abstract

The latest Planck results show a power deficit in the temperature anisotropies near $\ell \approx 20$ in the cosmic microwave background (CMB). This observation can hardly be explained within the standard inflationary $\Lambda$-cold-dark-matter ($\Lambda$CDM) scenario. In this paper we consider a string theory inspired inflationary model (axion monodromy inflation) with a step-like modulation in the potential which gives rise to observable signatures in the primordial perturbations. One interesting phenomenon is that the primordial scalar modes experience a sudden suppression at a critical scale when the modulation occurs. By fitting to the CMB data, we find that the model can nicely explain the $\ell \approx 20$ power deficit anomaly as well as predict specific patterns in the temperature-polarization correlation and polarization autocorrelation spectra. Though the significance of the result is not sufficient to claim a detection, our analysis reveals that fundamental physics at extremely high energy scales, namely, some effects inspired by string theory, may be observationally testable in forthcoming cosmological experiments.