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Search for charge non-conservation and Pauli exclusion principle violation with the Majorana Demonstrator

Nature Physics (2024)Cite this article

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Abstract

Charge conservation and the Pauli exclusion principle result from fundamental symmetries in the standard model of particle physics, and are typically taken as axiomatic. High-precision tests for small violations of these symmetries could point to new physics. Here we consider three models for violation of these processes, which would produce detectable ionization in the high-purity germanium detectors of the Majorana Demonstrator experiment. Using a 37.5 kg yr exposure, we report a lower limit on the electron mean lifetime, improving the previous best limit for the \(e\to {\nu }_{e}\overline{{\nu }_{e}}{\nu }_{e}\) decay channel by more than an order of magnitude. We also present searches for two types of violation of the Pauli exclusion principle, setting limits on the probability of an electron to be found in a symmetric quantum state.

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Fig. 1: Three processes disallowed by quantum mechanics that would produce ionization in Ge atoms.
Fig. 2: A charge non-conserving decay \({\boldsymbol{e}}\to {\mathbf{\nu}}_{\boldsymbol{e}}{\overline{\mathbf{\nu}}}_{\boldsymbol{e}}{\mathbf{\nu}}_{\boldsymbol{e}}\) from a Ge K-shell electron would produce a peak at 11.1 keV.
Fig. 3: The combined 228Th calibration spectrum from all active detectors in the Majorana Demonstrator.
Fig. 4: Searching for a violation of the Pauli exclusion principle via detection of an ‘echo’ peak.
Fig. 5: A PEP-violating transition of an L-shell electron to the fully occupied K shell in Ge would produce a peak at 10.6 keV.

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Source data are provided with this paper.

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The analysis codes are available from the corresponding authors on reasonable request.

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Acknowledgements

This material is based upon work supported by the US Department of Energy, Office of Science, Office of Nuclear Physics under contract/award numbers DE-AC02-05CH11231, DE-AC05-00OR22725, DE-AC05-76RL0130, DE-FG02-97ER41020, DE-FG02-97ER41033, DE-FG02-97ER41041, DE-SC0012612, DE-SC0014445, DE-SC0018060, DE-SC0022339 and LANLEM77/LANLEM78. We acknowledge support from the Particle Astrophysics Program and Nuclear Physics Program of the National Science Foundation through grant numbers MRI-0923142, PHY-1003399, PHY-1102292, PHY-1206314, PHY-1614611, PHY-1812409, PHY-1812356, PHY-2111140 and PHY-2209530. We gratefully acknowledge the support of the Laboratory Directed Research & Development (LDRD) programme at Lawrence Berkeley National Laboratory for this work. We gratefully acknowledge the support of the US Department of Energy through the Los Alamos National Laboratory LDRD Program, the Oak Ridge National Laboratory LDRD Program and the Pacific Northwest National Laboratory LDRD Program for this work. We gratefully acknowledge the support of the South Dakota Board of Regents Competitive Research Grant. We acknowledge the support of the Natural Sciences and Engineering Research Council of Canada, funding reference number SAPIN-2017-00023, and from the Canada Foundation for Innovation John R. Evans Leaders Fund. We acknowledge support from the 2020/2021 L’Oréal-UNESCO for Women in Science Programme. This research used resources provided by the Oak Ridge Leadership Computing Facility at Oak Ridge National Laboratory and by the National Energy Research Scientific Computing Center, a US Department of Energy Office of Science User Facility. We thank our hosts and colleagues at the Sanford Underground Research Facility for their support.

Author information

Author notes

  1. C. J. Barton

    Present address: Roma Tre University and INFN Roma Tre, Rome, Italy

  2. I. Kim & N. W. Ruof

    Present address: Lawrence Livermore National Laboratory, Livermore, CA, USA

  3. A. Li

    Present address: University of California San Diego, La Jolla, CA, US

  4. E. L. Martin

    Present address: Duke University, Durham, NC, USA

  5. T. K. Oli

    Present address: Argonne National Laboratory, Lemont, IL, USA

  6. B. X. Zhu

    Present address: Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA, USA

Authors and Affiliations

  1. Pacific Northwest National Laboratory, Richland, WA, USA

    I. J. Arnquist, E. W. Hoppe & R. T. Kouzes

  2. Department of Physics and Astronomy, University of South Carolina, Columbia, SC, USA

    F. T. Avignone III, T. E. Lannen V & D. Tedeschi

  3. Oak Ridge National Laboratory, Oak Ridge, TN, USA

    F. T. Avignone III, Yu. Efremenko, M. P. Green, I. S. Guinn, V. E. Guiseppe, J. M. López-Castaño, D. C. Radford, R. L. Varner, J. F. Wilkerson & C.-H. Yu

  4. National Research Center “Kurchatov Institute” Institute for Theoretical and Experimental Physics, Moscow, Russia

    A. S. Barabash

  5. Department of Physics, University of South Dakota, Vermillion, SD, USA

    C. J. Barton, T. K. Oli, L. S. Paudel & W. Xu

  6. Department of Physics and Astronomy, University of North Carolina, Chapel Hill, NC, USA

    K. H. Bhimani, B. Bos, T. S. Caldwell, M. L. Clark, J. Gruszko, C. R. Haufe, R. Henning, D. Hervas Aguilar, A. Li, E. L. Martin, A. L. Reine & J. F. Wilkerson

  7. Triangle Universities Nuclear Laboratory, Durham, NC, USA

    K. H. Bhimani, E. Blalock, B. Bos, M. Busch, M. L. Clark, M. P. Green, J. Gruszko, C. R. Haufe, R. Henning, D. Hervas Aguilar, A. Li, E. L. Martin, A. L. Reine & J. F. Wilkerson

  8. Department of Physics, North Carolina State University, Raleigh, NC, USA

    E. Blalock & M. P. Green

  9. Department of Physics, Duke University, Durham, NC, USA

    M. Busch

  10. Center for Experimental Nuclear Physics and Astrophysics, and Department of Physics, University of Washington, Seattle, WA, USA

    M. Buuck, J. A. Detwiler, A. Hostiuc, N. W. Ruof & C. Wiseman

  11. Nuclear Science Division, Lawrence Berkeley National Laboratory, Berkeley, CA, USA

    Y-D. Chan & A. W. P. Poon

  12. South Dakota Mines, Rapid City, SD, USA

    C. D. Christofferson

  13. Los Alamos National Laboratory, Los Alamos, NM, USA

    P.-H. Chu, S. R. Elliott, I. Kim, R. Massarczyk, S. J. Meijer, K. Rielage, D. C. Schaper & B. X. Zhu

  14. Centro de Investigaciones Energéticas, Medioambientales y Tecnológicas, CIEMAT 28040, Madrid, Spain

    C. Cuesta

  15. Department of Physics and Astronomy, University of Tennessee, Knoxville, TN, USA

    Yu. Efremenko

  16. Research Center for Nuclear Physics, Osaka University, Ibaraki, Japan

    H. Ejiri

  17. Physics Department, Williams College, Williamstown, MA, USA

    G. K. Giovanetti

  18. Tennessee Tech University, Cookeville, TN, USA

    M. F. Kidd

  19. Department of Physics, Engineering Physics and Astronomy, Queen’s University, Kingston, Ontario, Canada

    R. D. Martin

  20. IU Center for Exploration of Energy and Matter, and Department of Physics, Indiana University, Bloomington, IN, USA

    W. Pettus

  21. Joint Institute for Nuclear Research, Dubna, Russia

    S. Vasilyev

Consortia

The MAJORANA Collaboration

  • I. J. Arnquist
  • , F. T. Avignone III
  • , A. S. Barabash
  • , C. J. Barton
  • , K. H. Bhimani
  • , E. Blalock
  • , B. Bos
  • , M. Busch
  • , M. Buuck
  • , T. S. Caldwell
  • , Y-D. Chan
  • , C. D. Christofferson
  • , P.-H. Chu
  • , M. L. Clark
  • , C. Cuesta
  • , J. A. Detwiler
  • , Yu. Efremenko
  • , H. Ejiri
  • , S. R. Elliott
  • , G. K. Giovanetti
  • , M. P. Green
  • , J. Gruszko
  • , I. S. Guinn
  • , V. E. Guiseppe
  • , C. R. Haufe
  • , R. Henning
  • , D. Hervas Aguilar
  • , E. W. Hoppe
  • , A. Hostiuc
  • , M. F. Kidd
  • , I. Kim
  • , R. T. Kouzes
  • , T. E. Lannen V
  • , A. Li
  • , J. M. López-Castaño
  • , E. L. Martin
  • , R. D. Martin
  • , R. Massarczyk
  • , S. J. Meijer
  • , T. K. Oli
  • , L. S. Paudel
  • , W. Pettus
  • , A. W. P. Poon
  • , D. C. Radford
  • , A. L. Reine
  • , K. Rielage
  • , N. W. Ruof
  • , D. C. Schaper
  • , D. Tedeschi
  • , R. L. Varner
  • , S. Vasilyev
  • , J. F. Wilkerson
  • , C. Wiseman
  • , W. Xu
  • , C.-H. Yu
  •  & B. X. Zhu

Contributions

All authors were involved in various aspects of detector construction, operation, maintenance, data acquisition, data-taking shifts, software development, data processing and analysis. C.W. and I.K. developed the low-energy data cleaning, and low-energy statistical analysis and spectrum fit techniques. J.M.L.-C. and C.W. conducted the high-energy spectral analysis and derived the limit on the Type I PEP-violating process. I.K. derived limits for the electron lifetime and Type III PEP-violating process. C.W. and I.K. wrote the paper. All authors reviewed, commented and approved the results and the final version of the paper.

Corresponding authors

Correspondence to I. Kim or C. Wiseman.

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Competing interests

The authors declare no competing interests.

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Peer review information

Nature Physics thanks Miriam Diamond, Ziqing Hong, Rabindra Mohapatra and Alessio Porcelli for their contribution to the peer review of this work.

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Extended data

Extended Data Fig. 1 Profiles of the likelihood function over the branching ratio B = β2/2, defined as the ratio of lifetimes between PEP-obeying and PEP-violating atomic transitions of electrons.

DEP: β2/2 ≤ 3.22e−04 (90% CL). SEP: β2/2 ≤ 9.99e−04 (90%). Combined: β2/2 ≤ 3.69e − 04 (90%). The profiles from the single-escape peak region (dotted) and the double-escape peak region (dot-dashed) are added and shifted to produce the combined curve (solid black). The upper limits are computed at the intersection Δχ2 = 2.71, representing the 90% confidence level. Vertical lines representing the 90% upper limits are added for reference.

Extended Data Table 1 Best-fit parameters for the germanium peak shape function in the single-escape peak (SEP) and double-escape peak (DEP) regions
Full size table

Source data

Source Data Fig. 2

Histogram data points with brief description in header.

Source Data Fig. 3

Histogram data points with brief description in header.

Source Data Fig. 4

One file includes data for the top and bottom plots. Histogram data points with brief description in header.

Source Data Fig. 5

Histogram data points with brief description in header.

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The MAJORANA Collaboration. Search for charge non-conservation and Pauli exclusion principle violation with the Majorana Demonstrator. Nat. Phys. (2024). https://doi.org/10.1038/s41567-024-02437-9

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