Grand unified gauge-boson condensation on the cosmic string

Expectation values of grand unified Higgs scalars can be strongly changed in the core of the cosmic string. We show that in certain cases such unusual Higgs structures imply the existence of nonzero classical gauge currents in the lowest-energy state of the system. This automatically triggers the condensation of the grand unified gauge bosons interacting linearly with this current, which could be either trivial or nontrivial under the Å(1) subgroup responsible for the string. For the former, the gauge-boson condensate accumulated in the core of the defect is strictly radial, while in the latter case it also acquires an azimuthal (and magnetic) component. Existence of such types of condensates on the boundaries of the expanding vacuum bubbles (which arise in high-temperature phase transitions) can play an important role in creating the present baryon asymmetry.