Probing the Solar ⁸B Neutrino Fog with XENONnT

We report a 3.3⁢𝜎 measurement of coherent elastic neutrino-nucleus scattering from solar ⁸B neutrinos using a 6.77 t×yr exposure from the XENONnT experiment, inferring a solar ⁸B neutrino flux of (5+3−2)×10⁶ cm⁻² s⁻¹, consistent with previous measurements. In the presence of the ⁸B “neutrino fog,” we find no evidence for light dark matter, and observe diminishing returns in sensitivity with increasing exposure. A 93% increase in exposure from the previous search improves the median sensitivity to the nucleon scattering cross section for a 5 GeV/𝑐² spin-independent weakly interacting massive particle by 10%. The dataset was also used to measure the weak mixing angle at ∼0.02 GeV/𝑐 momentum transfer and constrain physics beyond the Standard Model.