Extracting Particle Physics Information from Direct Detection of Dark
  Matter with Minimal Assumptions
  In the absence of direct accelerator data to constrain particle models, and
given existing astrophysical uncertainties associated with the phase space
distribution of WIMP dark matter in our galactic halo, extracting information
on fundamental particle microphysics from possible signals in underground
direct detectors will be challenging. Given these challenges we explore the
requirements for direct detection of dark matter experiments to extract
information on fundamental particle physics interactions. In particular, using
Bayesian methods, we explore the quantitative distinctions that allow
differentiation between different non-relativistic effective operators, as a
function of the number of detected events, for a variety of possible operators
that might generate the detected distribution. Without a spinless target one
cannot distinguish between spin-dependent and spin-independent interactions. In
general, of order 50 events would be required to definitively determine that
the fundamental dark matter scattering amplitude is momentum independent, even
in the optimistic case of minimal detector backgrounds and no inelastic
scattering contributions. This bound can be improved with reduced uncertainties
in the dark matter velocity distribution.
