Brane necklaces and brane coils

Abstract

We investigate the evolution of the networks of the cosmic strings in angled brane inflation. We show how they can be distinguished from the conventional ones. The cosmic strings in angled inflation are the daughter $D_{p-2}$ branes that are extended between the mother $D_p$ branes. In the effective action, the strings should have a moduli, since the endpoints of the $D_{p-2}$ branes can move freely on the $D_p$ branes. Then naturally the position of the $D_{p-2}$ branes, which corresponds to the moduli of the $(1+1)$-dimensional effective action, can vary along the cosmic strings. The variation of the moduli results in the peculiar $(1+1)$-dimensional kink configurations. The kinks are the monopoles on the strings. Therefore, the cosmic strings in angled inflation become necklaces. The loops of the necklaces can shrink to produce stable winding states, which look like coils. We show why the cosmological implications of the brane necklaces are important. We point out that the cosmic strings in generic models of brane inflation should become necklaces, depending on the structure of the compactified space and the effective potential of the model.