ISOVECTOR MESON-EXCHANGE CURRENTS IN THE LIGHT-FRONT DYNAMICS

In the light-front dynamics, there is no pair term that plays the role of the dominant isovector pion exchange current. This current gives r ise to the large and experimentally observed contribution to the deute ron electrodisintegration cross-section near threshold for pseudo-scal ar pi NN coupling. We show analytically that in leading 1/m order the amplitude in the light-front dynamics coincides, however, with the one given by the pair term. At high Q(2), it consists of two equal parts. One comes from extra components of the deuteron and final state relat ivistic wave functions. The other results from the contact NN pi gamma interaction which appears in the light-front dynamics. This provides a transparent link between relativistic and non-relativistic approache s.