Prospects and Blind Spots for Neutralino Dark Matter

We evaluate current observational limits and their future reach for neutralino dark that is an admixture of bino, wino, and Higgsino. Experimental constraints can be weakened and in some cases nullified through either of two mechanisms: 1) purity, whereby dark matter is close to pure bino, wino, or Higgsino, or 2) blind spots, whereby the relevant couplings of dark matter to the Z and Higgs bosons vanish identically. We analytically identify all blind spots relevant to spin independent and dependent scattering and show that they occur for diverse choices for the relative signs among M1, M2, and μ. At present, bounds from XENON100 and IceCube are evaded in large swaths of parameter space—including the well-tempered neutralino. Because our analysis is purposefully agnostic about the fine-tuning of electroweak symmetry breaking, our results apply to natural theories as well as split supersymmetry. Future observations such as XENON1T will cut deeply into the natural regions of neutralino dark matter so that only the pure and blind spot regions will be allowed.