$x$ and $\xi$ scaling of the nuclear structure function at large $x$

Inclusive electron scattering data are presented for ${}^2\mathrm{H},$ C, Fe, and Au targets at an incident electron energy of 4.045 GeV for a range of momentum transfers from $Q^2=1\mathrm{}$ to $7\hspace{0.5em}(\mathrm{GeV}{/c)}^2.$ Data were taken at Jefferson Laboratory for low values of energy loss, corresponding to values of Bjorken $x\gtrsim 1.$ The structure functions do not show scaling in x in this range, where inelastic scattering is not expected to dominate the cross section. The data do show scaling, however, in the Nachtmann variable $\xi .$ This scaling appears to be the result of Bloom- Gilman duality in the nucleon structure function combined with the Fermi motion of the nucleons in the nucleus. The resulting extension of scaling to larger values of $\xi$ opens up the possibility of accessing nuclear structure functions in the high-$x$ region at lower values of $Q^2$ than previously believed.