Primordial gravitational waves and the collapse of the wave function

TL;DR

This paper investigates how a self-induced wave function collapse during inflation affects primordial gravitational waves, finding a strong suppression of tensor modes that remains consistent with current observational limits.

Contribution

It introduces a calculation of the tensor power spectrum under the self-induced collapse hypothesis within semiclassical gravity, highlighting its impact on gravitational wave amplitude.

Findings

Tensor modes are strongly suppressed by the collapse hypothesis.

The tensor-to-scalar ratio remains within observational bounds.

The model is compatible with BICEP/KECK and Planck data.

Abstract

"The self-induced collapse hypothesis" was introduced by D. Sudarsky and collaborators to explain the origin of cosmic structure from a perfect isotropic and homogeneous universe during the inflationary regime. In this paper, we calculate the power spectrum for the tensor modes, within the semiclassical gravity approximation, with the additional hypothesis of a generic self-induced collapse of the inflaton's wave function; we also compute an estimate for the tensor-to-scalar ratio. Based on this calculation, we show that the considered proposal exhibits a strong suppression of the tensor modes amplitude; nevertheless, the corresponding amplitude is still consistent with the joint BICEP/KECK and Planck Collaboration's limit on the tensor-to-scalar ratio.