RESPONSE OF NONRELATIVISTIC CONFINED SYSTEMS

We study the nonrelativistic response of a ''diquark'' bound by confin ing forces, for which perturbation theory in the interaction fails. As nonperturbative alternatives we consider the Gersch-Rodriguez-Smith ( GRS) theory and a summation method. We show that, contrary to the case of singular repulsive forces, the GRS theory can generally be applied to confined systems. When expressed in the GRS-West kinematic variabl e y, the response has a standard asymptotic limit and calculable domin ant corrections of orders 1/q, 1/q2. That theory therefore clearly dem onstrates how constituents, confined before and after the absorption o f the transferred momentum and energy, behave as asymptotically free p articles. We compare the GRS results with those of a summation method for harmonic and square-well confinement and also discuss the converge nce of the GRS series for the response in powers of 1/q.