Temperature Dependence ofS(Q, ω)in SuperfluidHe4

Abstract

The dynamic structure factor, $S(Q, \omega )$, for superfluid ${}_{}{}^4{}_{}{}^{}\mathrm{He}$ at finite temperatures is described as the sum of two components: a "superfluid" component with a shape characteristic of $S(Q, \omega )$ at $T=0\mathrm{}$ and a weight $\frac{{\rho }_s}{\rho }$, and a "normal-fluid" component with a shape characteristic of $S(Q, \omega )$ for nonsuperfluid ${}_{}{}^4{}_{}{}^{}\mathrm{He}$ and a weight $\frac{{\rho }_n}{\rho }$.