Figure 1

Inelastic x-ray scattering spectra of liquid ${}^3\mathrm{He}$ at $T=1.10\pm 0.05\mathrm{K}$ and saturated vapor pressure with the best fitting damped harmonic oscillator model functions at the indicated $Q$ values. For clarity reasons each spectrum has been multiplied by a factor of 3 with respect to the preceding one in the figure.Reuse & Permissions

Figure 2

Experimental IXS spectrum of liquid ${}^3\mathrm{He}$ for $Q=1.35{\AA }^{-1}$ along with the energy resolution, the best DHO fit to the data, and the unconvoluted DHO function. The lower panel reports the residual of the fit in standard deviation units.Reuse & Permissions

Figure 3

Upper panel: dispersion of the zero-sound mode. Solid circles: present results obtained using the DHO line shape ansatz; open triangles: present results obtained using the additive approach with Gaussian $n(p)$; open circles: INS results from Ref. 15 ($T=0.12\mathrm{K}$). The shaded area represents the particle-hole band calculated according to Ref. 18; the full line at low-$Q$ emphasizes the initial linear dependence of the dispersion curve; the dotted line represents the recoil energy of ${}^3\mathrm{He}$ which corresponds as well to the dispersion curve in the $Q\to \infty$ limit (impulse approximation). Lower panel: intrinsic Brillouin widths, same symbols as above. The full line shows the initial quadratic dependence on $Q$ of the FWHM; the dotted line (right $y$ axis) reports the experimental $S(Q)$ from Ref. 30.Reuse & Permissions