Snowmass whitepaper: Exploring natural SUSY via direct and indirect
  detection of higgsino-like WIMPs
  Supersymmetric models with low electroweak fine-tuning contain light
higgsinos with mass not too far from m_h\simeq 125 GeV, while other sparticles
can be much heavier. In the R-parity conserving MSSM, the lightest neutralino
is then a higgsino-like WIMP (albeit with non-negligible gaugino components),
with thermal relic density well below measured values. This leaves room for
axions (or other, perhaps not as well motivated, stable particles) to function
as co-dark matter particles. The local WIMP abundance is then expected to be
below standard estimates, and direct and indirect detection rates must be
accordingly rescaled. We calculate rescaled direct and indirect higgsino-like
WIMP detection rates in SUSY models that fulfil the electroweak naturalness
condition. In spite of the rescaling, we find that ton-scale noble liquid
detectors can probe the entire higgsino-like WIMP parameter space, so that
these experiments should either discover WIMPs or exclude the concept of
electroweak naturalness in R-parity conserving natural SUSY models. Prospects
for spin-dependent or indirect detection are more limited due in part to the
rescaling effect.
