Implications of first neutrino-induced nuclear recoil measurements in direct detection experiments: Probing nonstandard interaction via CEνNS

Abstract

PandaX-4T and XENONnT have recently reported the first measurement of nuclear recoils induced by the B8 solar neutrino flux, through the coherent elastic neutrino-nucleus scattering (CEνNS) channel. As long anticipated, this is an important milestone for dark matter searches as well as for neutrino physics. This measurement means that these detectors have reached exposures such that searches for low mass, ≲10 GeV dark matter cannot be analyzed using the background-free paradigm going forward. It also opens a new era for these detectors to be used as neutrino observatories. In this paper we assess the sensitivity of these new measurements to new physics in the neutrino sector. We focus on neutrino nonstandard interactions (NSI) and show that—despite the still moderately low statistical significance of the signals—these data already provide valuable information. We find that limits on NSI from PandaX-4T and XENONnT measurements are comparable to those derived using combined COHERENT CsI and LAr data. Furthermore, they provide sensitivity to pure τ flavor parameters that are not accessible using stopped-pion or reactor sources. With larger exposures and consequently improvements of statistical uncertainties, forthcoming data from these experiments will provide important, novel results for CEνNS-related physics. Published by the American Physical Society 2025