Kinematical and chemical vertical structure of the Galactic thick disk
  II. A lack of dark matter in the solar neighborhood
  We estimated the dynamical surface mass density Sigma at the solar position
between Z=1.5 and 4 kpc from the Galactic plane, as inferred from the
kinematics of thick disk stars. The formulation is exact within the limit of
validity of a few basic assumptions. The resulting trend of Sigma(Z) matches
the expectations of visible mass alone, and no dark component is required to
account for the observations. We extrapolate a dark matter (DM) density in the
solar neighborhood of 0+-1 mM_sun pc^-3, and all the current models of a
spherical DM halo are excluded at a confidence level higher than 4sigma. A
detailed analysis reveals that a small amount of DM is allowed in the volume
under study by the change of some input parameter or hypothesis, but not enough
to match the expectations of the models, except under an exotic combination of
non-standard assumptions. Identical results are obtained when repeating the
calculation with kinematical measurements available in the literature. We
demonstrate that a DM halo would be detected by our method, and therefore the
results have no straightforward interpretation. Only the presence of a highly
prolate (flattening q>2) DM halo can be reconciled with the observations, but
this is highly unlikely in LambdaCDM models. The results challenge the current
understanding of the spatial distribution and nature of the Galactic DM. In
particular, our results may indicate that any direct DM detection experiment is
doomed to fail, if the local density of the target particles is negligible.
