  We study the structure factors for spin-independent WIMP scattering off xenon
based on state-of-the-art large-scale shell-model calculations, which are shown
to yield a good spectroscopic description of all experimentally relevant
isotopes. Our results are based on the leading scalar one-body currents only.
At this level and for the momentum transfers relevant to direct dark matter
detection, the structure factors are in very good agreement with the
phenomenological Helm form factors used to give experimental limits for
WIMP-nucleon cross sections. In contrast to spin-dependent WIMP scattering, the
spin-independent channel, at the one-body level, is less sensitive to nuclear
structure details. In addition, we explicitly show that the structure factors
for inelastic scattering are suppressed by ~ 10^{-4} compared to the coherent
elastic scattering response. This implies that the detection of inelastic
scattering will be able to discriminate clearly between spin-independent and
spin-dependent scattering. Finally, we provide fits for all calculated
structure factors.
