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Testing light and heavy vector mediators with solar CE$ν$NS measurements

Valentina De Romeri, Dimitrios K. Papoulias, Federica Pompa, Gonzalo Sanchez Garcia, Christoph A. Ternes

Abstract

The recent observation of coherent elastic neutrino-nucleus scattering from solar $^8$B neutrinos in dark matter direct detection experiments has inaugurated the \emph{neutrino fog} era, highlighting the extended potential of these experiments as precision neutrino observatories. Recent measurements by the XENONnT, PandaX-4T, and LUX-ZEPLIN experiments provide new opportunities to test Standard Model predictions and to probe physics beyond it, in complementarity with dedicated neutrino facilities. We perform a combined analysis of nuclear recoil data from these three facilities to extract information on the solar $^8$B neutrino flux normalization and on the weak mixing angle at low-momentum transfer. We further investigate the impact of new vector interactions on the solar neutrino event rate, deriving constraints on nonstandard neutrino interactions and on scenarios with light vector mediators. Our results demonstrate that dark matter detectors are rapidly becoming complementary to terrestrial neutrino experiments in probing neutrino interactions, and already set competitive bounds on both light and heavy vector mediators.

Testing light and heavy vector mediators with solar CE$ν$NS measurements

Abstract

The recent observation of coherent elastic neutrino-nucleus scattering from solar B neutrinos in dark matter direct detection experiments has inaugurated the \emph{neutrino fog} era, highlighting the extended potential of these experiments as precision neutrino observatories. Recent measurements by the XENONnT, PandaX-4T, and LUX-ZEPLIN experiments provide new opportunities to test Standard Model predictions and to probe physics beyond it, in complementarity with dedicated neutrino facilities. We perform a combined analysis of nuclear recoil data from these three facilities to extract information on the solar B neutrino flux normalization and on the weak mixing angle at low-momentum transfer. We further investigate the impact of new vector interactions on the solar neutrino event rate, deriving constraints on nonstandard neutrino interactions and on scenarios with light vector mediators. Our results demonstrate that dark matter detectors are rapidly becoming complementary to terrestrial neutrino experiments in probing neutrino interactions, and already set competitive bounds on both light and heavy vector mediators.
Paper Structure (15 sections, 25 equations, 10 figures, 1 table)

This paper contains 15 sections, 25 equations, 10 figures, 1 table.

Table of Contents

  1. Introduction
  2. Theoretical framework and cross sections
  3. Neutrino nonstandard interactions and light vector mediators
  4. Neutrino propagation in the Sun
  5. CE NS cross sections
  6. CE NS cross section in the Standard Model
  7. CE NS cross section with NSI
  8. CE NS cross section in presence of new light vector mediators
  9. Data analysis
  10. Results
  11. SM physics: $^8$B flux and weak mixing angle
  12. Neutrino NSI
  13. Light vector mediators
  14. Conclusions
  15. Individual bounds on light vector mediators

Figures (10)

  • Figure 1: Left panel: The $\Delta\chi^2$ profiles for the determination of the $^8$B solar neutrino flux for PandaX-4T (dotted green), XENONnT (dashed blue), LZ (dot-dashed orange), and the combined analysis (solid magenta). Right panel: $^8$B solar neutrino flux determination from our individual and combined analyses of solar CE NS data, in comparison with other experimental measurements from neutral-current reactions Baxter:2021pqoSNO:2011hxdXENON:2024ijkPandaX:2024muvLZ:2025igz, as well as predictions from low- and high-metallicity solar models Vinyoles:2016djt. The superimposed dotted bars represent the official flux determinations as reported by each Collaboration.
  • Figure 2: Left panel: The $\Delta\chi^2$ profiles for the determination of the weak mixing angle for PandaX-4T (dotted green), XENONnT (dashed blue), LZ (dot-dashed orange), and the combined analysis (solid magenta). The dashed vertical line corresponds to the expected value of $\sin^2\theta_W$ within the SM. Right panel: Our $1\sigma$ combined CE NS measurement, together with the ones from other experiments at different energy scales Majumdar:2022nbyDeRomeri:2022twgNuTeV:2001whxPVDIS:2014cmdSLACE158:2005uayQweak:2018tjfParticleDataGroup:2024cfkALEPH:2005abCDF:2018cnjATLAS:2015ihyATLAS:2018gqq. The running of the weak mixing angle as defined in the $\overline{\rm MS}$ renormalization scheme Erler:2017knjErler:2004in is also shown (gray dashed line).
  • Figure 3: Left panel: $90\%$ CL contours in the $(\epsilon_{ee}^{uV},\epsilon_{ee}^{dV})$ plane. All the other NSI parameters are fixed to zero. Green, blue and orange lines refer to PandaX-4T, XENONnT and LZ, respectively, while the pink region corresponds to their combined result. Right panel: $90\%$ CL contours from the combined analysis in the diagonal $(\epsilon_{\alpha\alpha}^{uV},\epsilon_{\alpha\alpha}^{dV})$ plane, with $\alpha = e,\mu,\tau$ in shaded pink, green and blue color, respectively, and all the other NSI parameters fixed to zero.
  • Figure 4: $90\%$ CL contours in the $(\epsilon_{ee}^{qV},\epsilon_{\mu\mu}^{qV})$ plane, with $q = u ~(d)$ in the left panel ( right panel). Green, blue and orange lines refer to PandaX-4T, XENONnT and LZ, respectively, while the pink region corresponds to their combined result. We report here in gray also the parameter space region compatible with the LMA-dark solution.
  • Figure 5: The allowed regions at 1$\sigma$, 2$\sigma$ and 3$\sigma$ for 2 degrees of freedom for all pairs of NSI parameters with $u$-quarks from the combined XENONnT + PandaX-4T + LZ analysis. In each panel, we minimize with respect to all other NSI parameters that are not shown.
  • ...and 5 more figures