The numerical model of Smith and Vilenkin is used to study the equilibrium properties of a system of strings in flat spacetime. When the energy density of the system is low, the dominant part of the string is in the form of closed loops of the smallest allowed size. At a certain critical density ${\rho }_c$ the system undergoes a phase transition characterized by formation of infinite strings. In the asymptotic regimes of ρ≫${\rho }_c$ and ρ≪${\rho }_c$ the numerical results agree with the analytic calculations by Frautschi, Carlitz, and by Mitchell and Turok.

• Received 28 September 1987

DOI:https://doi.org/10.1103/PhysRevD.37.885