Green function approach to mass fluctuation waves

In earlier work, a model Hamiltonian has been used to study in detail the effects of 4He impurities in solid 3He. Starting with this Hamiltonian we use the Green function method, with a suitable decoupling scheme, to study the "mass fluctuation" waves caused by the impurities, and also to study the effect of the impurity terms in the Hamiltonian on the magnons of the system. Expressions are presented for the shifted positions of the poles, in the energy plane, corresponding to the excitations concerned