Coupling of particles near threshold to shape oscillations

It is shown that the isoscalar (isovector) strength in the energy region ju st above the low-energy threshold, which is created by exciting particles t o the continuum in nuclei far from beta-stability lines, can be reduced (in creased) by the attractive (repulsive) coupling to isoscalar (isovector) sh ape oscillations. This is in contrast to the well-known fact that in beta-s table nuclei low-lying isoscalar (isovector) particle-hole strengths are in creased (reduced) by the attractive (repulsive) isoscalar (isovector) coupl ing. We also study the corepolarization effect on one-particle operators fo r bound particles, of which separation energies are appreciably smaller tha n those in beta-stable nuclei. [S0556-2813(98)04212-5].