Quark interchange effects in deuteron threshold electrodisintegration

The resonating group quark-cluster method is applied to deuteron threshold electrodisintegration at backward angles. We work in the momentum-space representation and restrict ourselves in numerical applications to the dominant two-nucleon cluster component. An analysis is made of the bare quark interchange effects as well as of the associated perturbative gluon exchange effects. We also consider a treatment within the quark-cluster method of the pion exchange currents. In order to describe the virtual gluon and pion effects we introduce an effective field-theory action for the quark-gluon-pion system. The problems of identifying the proper quark effects and of connecting the cluster method and the conventional Schroedinger equation wave functions are addressed phenomenologically. Numerical results are presented for the contributions of the bare quark interchange, of the gluon-recoil exchange corrections as well as of the wave-function normalization correction. We also give results of a numerical application to the pion exchange direct terms, which are the counterpart of the conventional meson exchange currents, and their associated quark interchange terms.