Cycloops: dark matter or a monopole problem for brane inflation?

We consider cosmic loop production by long string interactions incosmological models with compact extra dimensions. In the case that the compactmanifold is not simply connected, we focus on the possibility of loops wrappingaround non-trivial cycles and becoming topologically trapped. Such loops,denoted cycloops, behave like matter in the radiation era, posing a potentialmonopole problem. We calculate the number distribution and the energy densityof these objects as functions of cosmic time and use them to study cosmologicalconstraints imposed on simple brane inflation models. For typical choices ofparameters we find that to avoid cycloop domination before the matter-radiationtransition, the strings must be unacceptably light, namely $G\mu<10^{-18}$,unless some mechanism to dilute the cycloops is provided. By exploring the fullparameter space however, we are able to find models with $G\mu \sim 10^{-14}$,which is marginally consistent with brane inflation. In such models the cycloopcould provide an interesting dark matter candidate.Comment: 19 pages, 2 figures; minor updates, references added, submitted to JHE