A search for cosmic ray boosted light dark matter with the LUX-ZEPLIN experiment

Cosmic rays in the Milky Way may collide with sub-GeV dark matter, imparting sufficient kinetic energies to produce detectable signals in liquid xenon detectors. In this talk, I will present an analysis on light dark matter boosted by cosmic rays (CRDM) in the Milky Way, using data from the LUX-ZEPLIN experiment, a dual-phase xenon detector located at the Sanford Underground Research Facility in Lead, South Dakota, USA. This analysis uses a total exposure of 4.2 tonne-years from two science runs, and features a novel technique for tagging background events from Pb214 decays. Several important factors have been introduced and examined, including the contributions of heavy cosmic ray nuclei, as well as the inhomogeneity of cosmic rays and dark matter within the Milky Way. DARKPROP, a Monte Carlo simulation package, was utilized to account for Earth’s shielding effects, incorporating the chemical composition and the nuclear form factors of atoms in the Earth’s crust for CRDM propagation. Our preliminary results, which establish the most stringent constraints on the spin-independent dark matter–nucleon scattering cross section for CRDM models with masses between 100 keV and 1 GeV will be presented.