ON THE EFFECTIVE ACTION OF A DUAL DIRAC STRING IN A CLASSICAL-MODEL

The effective action of a dual Dirac string is determined within a 4-d imensional formulation of Dirac's extension of Electrodynamics supplem ented by the dual London equation of superconductivity. We identify th e effective action calculated for classical electromagnetic fields ind uced by a dual Dirac string with the string action and evaluate the st ring tension. Our string action differs from that found by Nambu.