Non-topological Cycloops

TL;DR

This paper introduces a mechanism for creating stable cosmic string loops with windings in extra dimensions, which could produce unique gravitational wave signals indicating the presence of extra dimensions.

Contribution

It presents a novel stabilization mechanism for cosmic string loops with windings in internal space, embedded in the Klebanov-Strassler geometry, with potential observable gravitational wave signatures.

Findings

Windings naturally arise in string networks prior to loop formation.

Angular momentum stabilizes windings even in simply connected manifolds.

Oscillating loops may produce distinctive gravitational wave signals.

Abstract

We propose a mechanism for the creation of cosmic string loops with dynamically stabilised windings in the internal space. Assuming a velocity correlations regime in the post-inflationary epoch, such windings are seen to arise naturally in string networks prior to loop formation. The angular momentum of the string in the compact space may then be sufficient to ensure that the windings remain stable after the loop chops off from the network, even if the internal manifold is simply connected. For concreteness we embed our model in the Klebanov-Strassler geometry, which provides a natural mechanism for brane inflation, as well a being one of the best understood compactification schemes in type IIB string theory. We see that the interaction of angular momentum with the string tension causes the loop to oscillate between phases of expansion and contraction. This, in principle, should give rise to a distinct gravitational wave signature, the future detection of which could provide indirect evidence for the existence of extra dimensions.