When backgrounds become signals: neutrino interactions in xenon-based dark matter detectors

TL;DR

This study leverages dual-phase xenon TPC dark matter detectors to study low-energy solar neutrino interactions via coherent elastic neutrino-nucleus scattering (CEνNS) and neutrino-electron scattering (νES). By combining data from XENONnT, PandaX-4T, and LZ, the authors perform a unified analysis of CEνNS and νES with detailed treatment of detector response, backgrounds, and solar neutrino fluxes, enabling precision tests of the Standard Model at low energies and exploration of BSM scenarios including neutrino electromagnetic properties and nonstandard interactions. The results include SM-consistent determinations of the $^{8}$B flux, upper limits on the hep flux, a low-energy measurement of the weak mixing angle, and competitive bounds on the neutrino magnetic moment, millicharge, tau-neutrino charge radius, NSI couplings, and a $L_\mu-L_\tau$ mediator. The study demonstrates that solar neutrino data from dark matter detectors provide valuable, complementary constraints to traditional neutrino experiments and will benefit from future improvements in detector sensitivity and background rejection.

Abstract

Direct detection dark matter experiments have proven to be compelling probes for studying low-energy neutrino interactions with both nuclei and atomic electrons, offering complementary information to accelerator and reactor-based neutrino experiments. Recently, the XENONnT and PandaX-4T collaborations reported the first evidence of coherent elastic neutrino-nucleus scattering from $^8\mathrm{B}$ solar neutrinos. Thanks to their excellent background rejection capabilities and distinctive signal signatures, dual-phase time projection chambers are also sensitive to $pp$ solar neutrinos via their elastic scattering off atomic electrons in the target material. Although this signal is subdominant within the Standard Model, it becomes significantly enhanced in many beyond the Standard Model scenarios, offering a unique opportunity to probe new physics in the low-energy regime. While the precision of current neutrino measurements from dark matter detectors remains lower than that achieved by dedicated neutrino experiments, their sensitivity to the tau neutrino component of solar neutrinos helps complete the overall picture, especially when investigating flavor-dependent new physics effects.

Figures (5)

• Figure 1: Left: Agreement between CE$\nu$NS data and SM prediction in the muon and electron neutrino flavor basis at $1\sigma$ CL for the solar neutrino data compared to the most stringent spallation neutron source and reactor neutrino results AtzoriCorona:2025xgjatzoricorona:2025ygn. Also shown is the total CE$\nu$NS combined fit. Right: Marginal $\Delta\chi^2$ result on the tau neutrino flavor, comparing the solar neutrino CE$\nu$NS result to that from the combined fit.
• Figure 2: Left: Solar neutrino flux normalization measurements at $1\sigma$ CL from the XnT and P4T data, together with their combination compared to the prediction from the GS98 solar model Vitagliano:2019yzm. Right: The $1\sigma$ CL results for the $^8\mathrm{B}$ (top) and 90% CL limits for the hep (bottom) solar neutrino fluxes. Also shown is the constraint on the hep flux from the SNO experiment SNO:2006dke.
• Figure 3: Left: Measurements of the weak mixing angle at low energy from solar neutrino data, both through ER and NR, compared with other available constraints atzoricorona:2025ygnAtzoriCorona:2025xgjWoodAPVDzuba:2012kxAnthony:2005pmAndroic:2018kni. The red line depicts the SM prediction for the weak mixing angle PhysRevD.110.030001. The arrows refer to upper limits from the dataset which show less constraining power. Right: Marginal $\Delta\chi^2$ for the $\tau$ neutrino charge radius from each solar neutrino dataset analysed in this work, compared to the updated result of a global fit of neutrino-electron and CE$\nu$NS data (green curve) AtzoriCorona:2025xwr.
• Figure 4: Summary of existing limits at 90% CL on the neutrino magnetic moment (left) and neutrino millicharge (right) from a variety of experiments AtzoriCorona:2022jebBeda:2012zzTEXONO:2006xdsBorexino:2017fbdSuper-Kamiokande:2004wqkAtzoriCorona:2022qrfMUNU:2005xnzAllen:1992qeAhrens:1990fpLSND:2001aknGiunti:2014ixaXMASS:2020zkeParticleDataGroup:2024cfkCONUS:2022qbbXENONCollaboration:2022kmb. The limits are divided into flavor components, and also those on the effective solar parameters are shown. In orange we display the best current limits, which have to be compared to the results obtained from the analysis of ER data from XnT, P4T and LZ carried out in this work.
• Figure 5: Left: Constraints on flavor-preserving NSI at 90% CL from CE$\nu$NS solar neutrino data compared to the other CE$\nu$NS available constraints and the result of a CE$\nu$NS combined fit (green contour). The red cross indicates the SM solution. Right: Constraints at $2\sigma$ CL on the $L_\mu-L_\tau$ light vector mediator model from ER and NR solar neutrino data compared to other experimental constraints BaBar:2016sciCCFR:1991lplAltmannshofer:2014pbaAtzoriCorona:2022moj and to the limit obtained from the latest $(g-2)_\mu$ experimental result and the lattice-QCD theoretical estimation Muong-2:2025xykAliberti:2025beg.