String Necklaces and Primordial Black Holes from Type IIB Strings

Understand

We consider a model of static cosmic string loops in type IIB string theory, where the strings wrap cycles within the internal space.

• The strings are not topologically stabilised, however the presence of a lifting potential traps the windings giving rise to kinky cycloops.
• We find that PBH formation occurs at early times in a small window, whilst at late times we observe the formation of dark matter relics in the scaling regime.
• This is in stark contrast to previous predictions based on field theoretic models.