Non-existence of five dimensional string cosmological models in Riemannian and Lyra geometries

In this paper, we have attempted to construct five dimensional string cosmological models in Riemannian and Lyra geometries. It is found that cosmic string models do not survive in both the theories. Subsequently, the vacuum cosmological models are constructed and discussed.     

Primordial black holes from monopoles connected by strings

Primordial black holes (PBHs) are known to be produced from collapsing cosmic defects such as domain walls and strings. In this paper we show how PBHs are produced in monopole-string networks.