Searches for Light Dark Matter and Evidence of Coherent Elastic Neutrino-Nucleus Scattering of Solar Neutrinos with the LUX-ZEPLIN (LZ) Experiment

We present searches for light dark matter (DM) with masses 3-9 GeV/c2 in the presence of coherent elastic neutrino-nucleus scattering (CEvNS) from 8B solar neutrinos with the LUX-ZEPLIN experiment. This analysis uses a 5.7 tonne-year exposure with data collected between March 2023 and April 2025. In an energy range spanning 1-6 keV, we report no significant excess of events attributable to dark matter nuclear recoils, but we observe a significant signal from 8B CEvNS interactions that is consistent with expectation. We set world-leading limits on spin-independent and spin-dependent-neutron DM-nucleon interactions for masses down to 5 GeV/c2. In the no-dark-matter scenario, we observe a signal consistent with 8B CEvNS events, corresponding to a 4.5σ statistical significance. This is the most significant evidence of 8B CEvNS interactions and is enabled by robust background modeling and mitigation techniques. This demonstrates LZ's ability to detect rare signals at keV-scale energies.