Can we overcome the neutrino floor at high masses?
  The neutrino floor is a barrier in the parameter space of weakly interacting
massive particles (WIMPs) below which discovery is impeded due to an almost
irreducible background of neutrinos. Directional gas time projection chambers
could discriminate against solar neutrinos, relevant for WIMP masses
$\lesssim$10 GeV. At higher masses $\gtrsim$100 GeV the floor is set by the
background of atmospheric neutrinos. Probing below this part of the floor would
require very large target exposures. Since gas-based detectors would be
prohibitively large at this scale, we instead reevaluate the prospects for
liquid noble experiments to probe below the neutrino floor. We combine all
potential methods of subtracting the neutrino background to determine how much
of this difficult to reach, but well-motivated, parameter space it is feasible
to reach. Most notably, we quantify whether a proposed directional signal in
xenon and argon experiments called "columnar recombination" can help in this
task. We find that even if the strength of this effect is amplified beyond
current experimental results, the quantity of directional information contained
in the recombination signal is too low to realistically discriminate against
the atmospheric neutrino background. Instead, benefiting from the refined
measurements of neutrino fluxes by experiments such as DUNE and JUNO will be
the most practical means to push direct WIMP searches below the neutrino floor.
For an ultimate global coordination of xenon and argon experiments, we show
that the neutrino floor is a surmountable barrier. The direct detection of 100
GeV-scale supersymmetric WIMPs may, eventually, be within reach.
