Traversable double-throat wormholes in a string cloud background

Abstract

This work constructs a new class of traversable wormhole solutions with a double-throat topology, modeled as a localized perturbation of the Ellis-Bronnikov metric in a string cloud background. Embedding diagrams and the analysis of curvature invariants, including the Kretschmann scalar and the Weyl invariant, illustrate the geometric transition from single to double-throat structures as a function of the perturbation amplitude. By imposing the zero-tidal condition, we derive analytical expressions for the energy density and pressures, showing an asymptotic $r^{-2}$ decay characteristic of a string cloud, endowed with the topology of a global monopole. A key finding is that the energy density converges to a positive constant at the center, with the radial pressure becoming negative. This local behavior provides the repulsive support necessary to inflate the inter-throat region with non-exotic matter, concentrating Null Energy Condition violations to the throat vicinities. These results suggest that multi-throat geometries offer a natural mechanism for localizing exotic matter while maintaining a physical asymptotic background.