Modeling High-Energy Nuclear Recoils in LZ with NEST for EFT Dark Matter Searches

The LUX-ZEPLIN (LZ) experiment utilizes a dual-phase xenon time projection chamber to primarily search for dark matter through WIMP-nucleon elastic scatterings. In this presentation, we will discuss the results of tuning the Noble Element Simulation Technique (NEST) model, which is used to model the scintillation and ionization yields from signal and background interactions in the xenon target. Using AmBe neutron calibration data, we extended the energy range for nuclear recoil modeling in LZ. This refinement improves the accuracy of nuclear recoil response modeling at higher energies, which is essential for effective field theory (EFT) analyses of WIMP-nucleon interactions. By expanding the energy window beyond conventional spin-independent and spin-dependent searches, the enhancement increases LZ's sensitivity to potential dark matter interactions.