Vorton Formation

In this paper we present the first analytic model for vorton formation. We start by deriving the microscopic string equations of motion in Witten's superconducting model, and show that in the relevant chiral limit these coincide with the ones obtained from the supersonic elastic models of Carter and Peter. We then numerically study a number of solutions of these equations of motion and thereby suggest criteria for deciding whether a given superconducting loop configuration can form a vorton. Finally, using a recently developed model for the evolution of currents in superconducting strings we conjecture, by comparison with these criteria, that string networks formed at the GUT phase transition should produce no vortons. On the other hand, a network formed at the electroweak scale can produce vortons accounting for up to 6% of the critical density. Some consequences of our results are discussed.Comment: 41 pages; color figures 3-6 not included, but available from authors. To appear in Phys. Rev.

Topological Defects in Contracting Universes

We study the behaviour and consequences of cosmic string networks in contracting universes. They approximately behave during the collapse phase as a radiation fluids. Scaling solutions describing this are derived and tested against high-resolution numerical simulations. A string network in a contracting universe, together with the gravitational radiation it generates, can affect the dynamics of the universe both locally and globally, and be an important source of radiation, entropy and inhomogeneity. We discuss possible implications for bouncing and cyclic models.Comment: Shorter version of astro-ph/0206287. To appear in Phys. Rev. Let

Multicolored Temperley-Lieb lattice models. The ground state

Using inversion relation, we calculate the ground state energy for the lattice integrable models, based on a recently obtained baxterization of non trivial multicolored generalization of Temperley-Lieb algebras. The simplest vertex and IRF models are analyzed and found to have a mass gap.Comment: 15 pages 2 figure

Pro-poor growth: the evidence beyond income.

It is widely agreed that economic growth is necessary for reducing poverty. It is also well-established that poverty is multi-dimensional and not fully explained by income levels alone. Therefore, this paper attempts to fill a relative gap in the pro-poor growth literature by examining the impact of income growth on non-income poverty, particularly child mortality. The results confirm that although changes in per capita income matter for non-income poverty outcomes, they may not matter as much as for income poverty or as much as other factors, particularly in low-income countries. For developing countries, we find that a 1 per cent increase in income per capita is associated with a 0.3 per cent decline in the child mortality rate, declining to just a 0.1 per cent reduction for Sub-Saharan Africa. In contrast, a country‟s level of literacy appears to have a larger impact on non-income poverty with a 1 per cent decline in illiteracy associated with as much as a 0.5 per cent decline in child mortality in low-income countries. Our results suggest that pro-poor growth policies must be more sensitive to the constraints that exist in poorer countries that reduce the impact of economic growth on poverty