Dark matter sensitivity of multi-ton liquid xenon detectors
  We study the sensitivity of multi ton-scale time projection chambers using a
liquid xenon target, e.g., the proposed DARWIN instrument, to spin-independent
and spin-dependent WIMP-nucleon scattering interactions. Taking into account
realistic backgrounds from the detector itself as well as from neutrinos, we
examine the impact of exposure, energy threshold, background rejection
efficiency and energy resolution on the dark matter sensitivity. With an
exposure of 200 t x y and assuming detector parameters which have been already
demonstrated experimentally, spin-independent cross sections as low as $2.5
\times 10^{-49}$ cm$^2$ can be probed for WIMP masses around 40 GeV/$c^2$.
Additional improvements in terms of background rejection and exposure will
further increase the sensitivity, while the ultimate WIMP science reach will be
limited by neutrinos scattering coherently off the xenon nuclei.
