PBH and DM from cosmic necklaces

TL;DR

This paper explores the formation and cosmological implications of cosmic necklaces and stable winding states in brane universe models, emphasizing their potential observational signatures distinct from conventional cosmic strings.

Contribution

It introduces the concept of cosmic necklaces with kinks and stable winding states arising from higher-dimensional brane dynamics, highlighting their significance in cosmology.

Findings

Cosmic necklaces with kinks can form in brane models.

Stable winding states are topologically protected in non-simply connected compact spaces.

These structures could produce observable cosmological signatures.

Abstract

Cosmic strings in the brane Universe have recently gained a great interest. I think the most interesting story is that future cosmological observations distinguish them from the conventional cosmic strings. If the strings are the higher-dimensional objects that can (at least initially) move along the compactified space, and finally settle down to (quasi-)degenerated vacua in the compactified space, then kinks should appear on the strings, which interpolate between the degenerated vacua. These kinks look like ``beads'' on the strings, which means that the strings turn into necklaces. Moreover, in the case that the compact manifold is not simply connected, the string loop that winds around a non-trivial circle is stable due to the topological reason. Since the existence of degenerated vacua and a non-trivial circle is the common feature of the brane models, it is important to study cosmological constraints on the cosmic necklaces and their stable winding states in the brane Universe.