Charged Bose condensate screening of hydrogenic impurities in two and three dimensions

We study screening effects of a three- and two-dimensional charged Bose con densate on the binding energy of a hydrogenic impurity. Many-body effects a re taken into account via a local-field correction. The variational method and the matrix diagonalization method are used to calculate the energies of the ground state and of excited states as functions of the condensate dens ity. With increasing boson density the binding energies decrease and vanish at a critical density. For a given density, Bose condensate screening is f ound to be more efficient than electron screening and the binding energies vanish at a lower density than for electron screening.