Strings and the Gauge Theory of Spacetime Defects

We present a new topological invariant todescribe space-time defects which is closely related tothe torsion tensor in a Riemann–Cartan manifold.By virtue of the topological current theory andφ-mapping method, we show that there must existmultistring objects generated from the zero points ofthe φ-mapping. These strings are topologicallyquantized. The topological quantum numbers are thewinding numbers described by the Hopf indices and the Brouwerdegrees of the φ-mapping.