CMB statistics in noncommutative inflation

TL;DR

This paper explores how noncommutative geometry during inflation can produce distinctive signatures in the CMB, such as parity violation and non-Gaussianities, offering potential observational evidence of quantum gravity effects.

Contribution

It demonstrates that noncommutative inflation can generate unique CMB signatures, providing a new way to test quantum gravity theories through cosmological observations.

Findings

Parity-violating modulations in the primordial spectrum

Odd non-Gaussian signatures with specific shape and scale dependence

Constraints on noncommutativity scale comparable to existing bounds

Abstract

Noncommutative geometry can provide effective description of physics at very short distances taking into account generic effects of quantum gravity. Inflation amplifies tiny quantum fluctuations in the early universe to macroscopic scales and may thus imprint high energy physics signatures in the cosmological perturbations that could be detected in the CMB. It is shown here that this can give rise to parity-violating modulations of the primordial spectrum and odd non-Gaussian signatures. The breaking of rotational invariance of the CMB provides constraints on the scale of noncommutativity that are competitive with the existing noncosmological bounds, and could explain the curious hemispherical asymmetry that has been claimed to be observed in the sky. This introduces also non-Gaussianity with peculiar shape- and scale-dependence, which in principle allows an independent cross-check of the presence of noncommutativity at inflation.