Sum rules for the dynamic structure function S(q, omega) in He-3-He-4
mixtures at zero temperature are calculated, using available results f
or the ground state properties. The different contributions to S(q, om
ega) coming from the He-3 and He-4 elementary excitations are analyzed
. Special attention is devoted to the effects of spin correlations on
the He-3 part of S(q, omega) and to the role of the cross term S(3,4)(
q, omega).