Dynamic Structure Function in 3he-4he Mixtures

Abstract

Relevant features of the dynamic structure function $S(q,\omega )$ in ${}^3$He-${}^4$He mixtures at zero temperature are investigated starting from known properties of the ground state. Sum rules are used to fix rigorous constraints to the different contributions to $S(q,\omega )$, coming from ${}^3$He and ${}^4$He elementary excitations, as well as to explore the role of the cross term $S^{(3,4)}(q,\omega )$. Both the low-$q$ (phonon-roton ${}^4$He excitations and 1p-1h ${}^3$He excitations) and high-$q$ (deep inelastic scattering) ranges are discussed.

arXiv comment29 pages, Plain TeX, 11 figures available by request from [email protected]