Logo
ScienceStack
Table of Contents
Fetching ...
Sign In

Searches for Light Dark Matter and Evidence of Coherent Elastic Neutrino-Nucleus Scattering of Solar Neutrinos with the LUX-ZEPLIN (LZ) Experiment

D. S. Akerib, A. K. Al Musalhi, F. Alder, B. J. Almquist, C. S. Amarasinghe, A. Ames, T. J. Anderson, N. Angelides, H. M. Araújo, J. E. Armstrong, M. Arthurs, A. Baker, S. Balashov, J. Bang, J. W. Bargemann, E. E. Barillier, D. Bauer, K. Beattie, A. Bhatti, T. P. Biesiadzinski, H. J. Birch, E. Bishop, G. M. Blockinger, C. A. J. Brew, P. Brás, S. Burdin, M. C. Carmona-Benitez, M. Carter, A. Chawla, H. Chen, Y. T. Chin, N. I. Chott, S. Contreras, M. V. Converse, R. Coronel, A. Cottle, G. Cox, D. Curran, C. E. Dahl, I. Darlington, S. Dave, A. David, J. Delgaudio, S. Dey, L. de Viveiros, L. Di Felice, C. Ding, J. E. Y. Dobson, E. Druszkiewicz, S. Dubey, C. L. Dunbar, S. R. Eriksen, S. Fayer, N. M. Fearon, N. Fieldhouse, S. Fiorucci, H. Flaecher, E. D. Fraser, T. M. A. Fruth, P. W. Gaemers, R. J. Gaitskell, A. Geffre, J. Genovesi, C. Ghag, J. Ghamsari, A. Ghosh, S. Ghosh, R. Gibbons, S. Gokhale, J. Green, M. G. D. van der Grinten, J. J. Haiston, C. R. Hall, T. Hall, R. H Hampp, S. J. Haselschwardt, M. A. Hernandez, S. A. Hertel, G. J. Homenides, M. Horn, D. Q. Huang, D. Hunt, E. Jacquet, R. S. James, K. Jenkins, A. C. Kaboth, A. C. Kamaha, M. K. Kannichankandy, D. Khaitan, A. Khazov, J. Kim, Y. D. Kim, D. Kodroff, E. V. Korolkova, H. Kraus, S. Kravitz, L. Kreczko, V. A. Kudryavtsev, C. Lawes, D. S. Leonard, K. T. Lesko, C. Levy, J. Lin, A. Lindote, W. H. Lippincott, J. Long, M. I. Lopes, W. Lorenzon, C. Lu, S. Luitz, W. Ma, V. Mahajan, P. A. Majewski, A. Manalaysay, R. L. Mannino, R. J. Matheson, C. Maupin, M. E. McCarthy, D. N. McKinsey, J. McLaughlin, J. B. McLaughlin, R. McMonigle, B. Mitra, E. Mizrachi, M. E. Monzani, K. Morå, E. Morrison, B. J. Mount, M. Murdy, A. St. J. Murphy, H. N. Nelson, F. Neves, A. Nguyen, C. L. O'Brien, F. H. O'Shea, I. Olcina, K. C. Oliver-Mallory, J. Orpwood, K. Y Oyulmaz, K. J. Palladino, N. J. Pannifer, N. Parveen, S. J. Patton, B. Penning, G. Pereira, E. Perry, T. Pershing, A. Piepke, S. S. Poudel, Y. Qie, J. Reichenbacher, C. A. Rhyne, G. R. C. Rischbieter, E. Ritchey, H. S. Riyat, R. Rosero, N. J. Rowe, T. Rushton, D. Rynders, S. Saltão, D. Santone, I. Sargeant, A. B. M. R. Sazzad, R. W. Schnee, G. Sehr, B. Shafer, S. Shaw, W. Sherman, K. Shi, T. Shutt, C. Silva, G. Sinev, J. Siniscalco, A. M. Slivar, R. Smith, V. N. Solovov, P. Sorensen, J. Soria, T. J. Sumner, A. Swain, M. Szydagis, D. R. Tiedt, M. Timalsina, D. R. Tovey, J. Tranter, M. Trask, K. Trengove, M. Tripathi, A. Usón, A. C. Vaitkus, O. Valentino, V. Velan, A. Wang, J. J. Wang, Y. Wang, L. Weeldreyer, T. J. Whitis, K. Wild, M. Williams, J. Winnicki, L. Wolf, F. L. H. Wolfs, S. Woodford, D. Woodward, C. J. Wright, Q. Xia, J. Xu, Y. Xu, M. Yeh, D. Yeum, J. Young, W. Zha, H. Zhang, T. Zhang, Y. Zhou

Abstract

We present searches for light dark matter (DM) with masses 3-9 GeV/$c^2$ in the presence of coherent elastic neutrino-nucleus scattering (CE$ν$NS) from $^{8}$B solar neutrinos with the LUX-ZEPLIN experiment. This analysis uses a 5.7 tonne-year exposure with data collected between March 2023 and April 2025. In an energy range spanning 1-6 keV, we report no significant excess of events attributable to dark matter nuclear recoils, but we observe a significant signal from $^{8}$B CE$ν$NS interactions that is consistent with expectation. We set world-leading limits on spin-independent and spin-dependent-neutron DM-nucleon interactions for masses down to 5 GeV/$c^2$. In the no-dark-matter scenario, we observe a signal consistent with $^{8}$B CE$ν$NS events, corresponding to a $4.5σ$ statistical significance. This is the most significant evidence of $^{8}$B CE$ν$NS interactions and is enabled by robust background modeling and mitigation techniques. This demonstrates LZ's ability to detect rare signals at keV-scale energies.

Searches for Light Dark Matter and Evidence of Coherent Elastic Neutrino-Nucleus Scattering of Solar Neutrinos with the LUX-ZEPLIN (LZ) Experiment

Abstract

We present searches for light dark matter (DM) with masses 3-9 GeV/ in the presence of coherent elastic neutrino-nucleus scattering (CENS) from B solar neutrinos with the LUX-ZEPLIN experiment. This analysis uses a 5.7 tonne-year exposure with data collected between March 2023 and April 2025. In an energy range spanning 1-6 keV, we report no significant excess of events attributable to dark matter nuclear recoils, but we observe a significant signal from B CENS interactions that is consistent with expectation. We set world-leading limits on spin-independent and spin-dependent-neutron DM-nucleon interactions for masses down to 5 GeV/. In the no-dark-matter scenario, we observe a signal consistent with B CENS events, corresponding to a statistical significance. This is the most significant evidence of B CENS interactions and is enabled by robust background modeling and mitigation techniques. This demonstrates LZ's ability to detect rare signals at keV-scale energies.

Paper Structure

This paper contains 5 sections, 8 figures, 2 tables.

Table of Contents

  1. Appendix - Spin Dependent DM Results
  2. Details of the Accidental Coincidence Model and Validation
  3. Details of the Nuclear Recoil Detector Response Model and Uncertainty Treatment
  4. Details on Bias Mitigation
  5. Limits in Terms of Number of DM Events

Figures (8)

  • Figure 1: Detection efficiency as a function of NR energy, after applying the S2 trigger (blue), $\geq3$-fold SS reconstruction (green), analysis selections (orange), and region-of-interest (black) in sequence. The uncertainty band (gray) includes the uncertainties associated with the yields and fluctuations in the NR response model and the efficiency of single-scatter reconstruction and analysis selections. Also shown are the DM recoil spectra (purple) for masses of 3 GeV/$c^{2}$, 5.5 GeV/$c^{2}$, and 9 GeV/$c^{2}$, assuming a cross-section of 10$^{-44}$ cm$^{2}$, before the application of detection efficiency. The predicted $^{8}$B CE$\nu$NS recoil spectrum (red) is similar to that of a DM particle with mass 5.5 GeV/$c^{2}$.
  • Figure 2: The 19 events comprising the final dataset passing all selections are shown as individual pie charts in the observable space {S1${c}$, S2${c}$}. Each pie chart depicts the relative fit contributions from the accidental coincidences (yellow) and $^{8}$B CE$\nu$NS (green) background components along with a 3 GeV/$c^{2}$ DM candidate (pink). The relative size of each pie chart is proportional to its contribution to 3 GeV/$c^{2}$ DM events. Contours enclose $1\sigma$ and $2\sigma$ model distributions. The data (black points) and best-fit model (solid blue line) in S1${c}$ and S2${c}$ projections are also shown. Shaded light blue (dark blue) bands depict the total (systematic-only) model uncertainty. The detector neutron component is subdominant and therefore not shown.
  • Figure 3: Upper limits (90% C.L.) on the spin-independent DM-nucleon cross section as a function of DM mass using the 5.7 tonne-year dataset are shown in the solid black line. The range of expected upper limits from background-only experiments are shown as green and yellow regions for 68% and 95% of experiments, respectively. The dashed black line shows the median expected upper limit, while the dotted black line shows the median $3\sigma$ discovery potential, using the post-fit model. The onset of the neutrino fog, as defined in OHare:2021utq, is shown as the shaded gray region. Other experimental limits are also shown XenonNT:LDM-NeutrinoFogPandaX:2022aacDarkSide-50:2022qzhPandaX2025.
  • Figure 4: Top: Measurement of $^{8}$B solar neutrino flux assuming the SM-predicted CE$\nu$NS cross-section and weak mixing angle. Predictions from low- and high-metallicity solar models are shown Vinyoles:2016djt alongside other experimental measurements aharmin2013combinedXenonNT:8BPanda:8B. Bottom: Measurement of the weak mixing angle assuming the SNO measurement of $^{8}$B solar-$\nu$ flux and SM CE$\nu$NS cross-section is shown. Also shown are other experimental results Wood_1997_APVAnthony_2005_SLAC_E158Androic_2018_QweakDeRomeri_2023_COHERENTSierra_2022_DresdenIIAlpizar:2025worDeRomeri_2025_CONUSPrescott_1979_eDIS_Old and the SM prediction ParticleDataGroup:2024cfk.
  • Figure 5: Upper limits (90% C.L.) from the 5.7 tonne-year analysis on the spin-dependent DM-proton (left) and DM-neutron (right) cross-section as a function of DM mass are shown with a solid black line. The observed limit uses the mean of the nuclear structure functions from PhysRevD.102.074018, with the gray band depicting the uncertainty from nuclear modeling in the models described in PhysRevD.102.074018Pirinen:2019gapPhysRevLett.128.072502. The median 3$\sigma$ discovery potential using the post-fit model is shown as the dotted black line. Other experimental limits for spin-dependent DM-proton amole2019darkLZ:2024WIMP and DM-neutron LZ:2024WIMPXENON:2023cxc scattering are also shown.
  • ...and 3 more figures