Destruction of Fermion Zero Modes on Cosmic Strings

Abstract

I examine the existence of zero energy fermion solutions (zero modes) on cosmic strings in an SO(10) grand unified theory. The current carrying capability of a cosmic string formed at one phase transition can be modified at subsequent phase transitions. I show that the zero modes may be destroyed and the conductivity of the string altered. I discuss the cosmological implications of this, and show that it allows vorton bounds to be relaxed.