Nicole Larsen

A wealth of astrophysical research supports the existence of dark matter in the universe, yet the exact nature of this unknown particle remains elusive. The Large Underground Xenon (LUX) experiment is a 370-kg dual-phase xenon-based time projection chamber (TPC) that seeks to detect dark matter candidates such as Weakly Interacting Massive Particles (WIMPs) through the light and ionization signals generated by their collisions with xenon nuclei. The first part of this talk details the design of the LUX experiment and describes several novel hardware developments that enable LUX to search for these rare events with extremely high precision. In 2013, with the release of the world’s first sub-zeptobarn spin-independent WIMP-nucleon cross-section limit, the LUX (Large Underground Xenon) experiment emerged as a frontrunner in the field of dark matter direct detection.

However, tension between experiments and the absence of a definitive positive detection suggest a search for answers outside the standard spin-independent/spin-dependent analyses. In particular, the standard analyses neglect momentum- and velocity-dependent interactions on the grounds that WIMP-nucleus collisions are nonrelativistic. At the parton level, this is not always the case, and moreover, models exist in which the standard spin-independent and spin-dependent interactions are subdominant to momentum- and velocity-dependent interactions. Recent theoretical work has identified a complete set of 14 possible independent WIMP-nucleon interactions using basic symmetries and an effective field theory formulation. In the second part of this talk we report on the extension of the LUX analysis to search for all 14 of these new interactions, we comment on the possible suppression of event rates due to operator interference, and we show that under this new framework LUX again exhibits world-leading sensitivity.