Cosmic Strings and Quintessence

Using torsion two-form we present a new Lorentz gauge invariant U(1) topological field theory in Riemann-Cartan space-time manifold U₄. By virtue of the decomposition theory of U(1) gauge potential and the Ф-mapping topological current theory, it is proven that the U(1) complex scalar field Ф can be looked upon as the order parameter field in our Universe, and a set of zero points of Ф(x) create the cosmic strings as the space-time defects in the early Universe. In the standard cosmology, this complex scalar order parameter field possesses negative pressure, provides an accelerating expansion of Universe, and be able to explain the inflation in the early Universe. Therefore this complex scalar field is not only the order parameter field created the cosmic strings in the early universe, but also reasonably behaves as the quintessence, the dark energy.