Searching for dark matter with liquid noble gas detectors (including the LZ and Xenon experiments ), and the potential for observing a new WIMP candidate below 125 GeV

Although there is as yet no confirmed evidence for detection of dark matter, many experiments are entering regimes where there is now a reasonable possibility of success. Weakly interacting massive particles (WIMPs) are among the leading dark matter candidates, largely because they would have been created in about the right abundance as thermal relics if their mass is ~ 100 GeV. A favorite hypothetical WIMP is the lowest-mass neutralino, a linear combination of the neutral fermionic superpartners predicted by supersymmetry. However, the tension that currently exists between experiment and simple supersymmetric models may indicate that it is desirable to consider alternative scenarios for how WIMPs can naturally arise. Here we consider a new candidate which resembles a neutralino, in that it is charge-neutral, has spin 1/2, and is made stable by having an R-parity of -1, but it is distinguished by various unusual features, including unconventional couplings to the W and Z bosons and a well-defined mass. We will discuss how either a neutralino or this new particle can be observed in 2-phase Xe and Ar direct detection experiments. A key feature is that the new particle is predicted to have a mass that is less than or equal to 125 GeV.