Probing the Solar $^8$B Neutrino Fog with XENONnT

TL;DR

This paper reports a significant measurement of solar $^8$B neutrino interactions using XENONnT, providing insights into neutrino flux, dark matter searches, and fundamental physics at low energies.

Contribution

First measurement of solar $^8$B neutrino coherent scattering with XENONnT, constraining neutrino flux and testing new physics at low momentum transfer.

Findings

Measured solar $^8$B neutrino flux consistent with previous results.

No evidence found for light dark matter in the presence of the neutrino fog.

Improved sensitivity to WIMP-nucleon cross section with increased exposure.

Abstract

We report a 3.3 $\sigma$ measurement of coherent elastic neutrino-nucleus scattering from solar $^8$B neutrinos using a 6.77 t$\times$yr exposure from the XENONnT experiment, inferring a solar $^8$B neutrino flux of $(5_{-2}^{+3})\times 10^6\,\mathrm{cm}^{-2}\mathrm{s}^{-1}$, consistent with previous measurements. In the presence of the $^8$B "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 5 GeV/$c^2$ weakly interacting massive particles-nucleon cross section by 10%. The dataset was also used to measure the weak mixing angle at $\sim$ 0.02 GeV/$c$ momentum transfer and constrain physics beyond the Standard Model.