First result of the scalar WIMP-pion interaction from the LUX-ZEPLIN experiment

The LUX-ZEPLIN (LZ) experiment, located at Sanford Underground Research Facility, is a direct detection dark matter experiment. LZ utilizes a dual-phase time projection chamber which contains 7 tonnes of liquid xenon in the active volume. LZ is optimized to search for weakly interacting massive particles (WIMPs) by probing the spin-independent and the spin-dependent WIMP-nucleon interactions. From chiral effective field theory (EFT), WIMPs can also interact with two nucleons via the exchange of a virtual pion. The WIMP-pion interaction is an important next-to-leading order correction from power counting of chiral EFT.

Based on the first science run, we constructed a model of the backgrounds and the detector response for this EFT search. In the region of interest, we used the model to obtain WIMP-pion recoils with WIMP masses between 6 and 10,000 GeV/c^2. We performed a profile-likelihood ratio analysis to study the sensitivity of LZ to these interactions. In this talk, we highlight the key backgrounds, data analysis techniques, and the signal model. We will update the status of the search.