Reexamination of inflation in noncommutative space-time after Planck results

TL;DR

This paper reevaluates inflation models in noncommutative space-time using Planck data, finding that such models struggle to simultaneously produce the observed spectral index running and acceptable tensor-to-scalar ratios.

Contribution

It provides a critical analysis of noncommutative inflation models against recent observational constraints, highlighting their limitations.

Findings

Noncommutative effects lead to either tiny spectral index running or large tensor-to-scalar ratio.

Chaotic and power-law inflation models with noncommutative effects are disfavored by Planck data.

The models cannot produce sufficient e-folds while matching observational data.

Abstract

An inflationary model in the framework of noncommutative space-time may generate a nontrivial running of the scalar spectral index, but usually induces a large tensor-to-scalar ratio simultaneously. With the latest observational data from the Planck mission, we reexamine the inflationary scenarios in a noncommutative space-time. We find that either the running of the spectral index is tiny compared with the recent observational result, or the tensor-to-scalar ratio is too large to allow a sufficient number of $e$-folds. As examples, we show that the chaotic and power-law inflation models with the noncommutative effects are not favored by the current Planck data.